Abstract
Background
Self‐administered questionnaires are widely used to collect data in epidemiological research, but non‐response reduces the effective sample size and can introduce bias. Finding ways to increase response to postal and electronic questionnaires would improve the quality of epidemiological research.
Objectives
To identify effective strategies to increase response to postal and electronic questionnaires.
Search methods
We searched 14 electronic databases up to December 2021 and manually searched the reference lists of relevant trials and reviews. We contacted the authors of all trials or reviews to ask about unpublished trials; where necessary, we also contacted authors to confirm the methods of allocation used and to clarify results presented.
Selection criteria
Randomised trials of methods to increase response to postal or electronic questionnaires. We assessed the eligibility of each trial using pre‐defined criteria.
Data collection and analysis
We extracted data on the trial participants, the intervention, the number randomised to intervention and comparison groups and allocation concealment. For each strategy, we estimated pooled odds ratios (OR) and 95% confidence intervals (CI) in a random‐effects model. We assessed evidence for selection bias using Egger's weighted regression method and Begg's rank correlation test and funnel plot. We assessed heterogeneity amongst trial odds ratios using a Chi2 test and quantified the degree of inconsistency between trial results using the I2 statistic.
Main results
Postal
We found 670 eligible trials that evaluated over 100 different strategies of increasing response to postal questionnaires. We found substantial heterogeneity amongst trial results in half of the strategies.
The odds of response almost doubled when: using monetary incentives (odds ratio (OR) 1.86; 95% confidence interval (CI) 1.73 to 1.99; heterogeneity I2 = 85%); using a telephone reminder (OR 1.96; 95% CI 1.03 to 3.74); and when clinical outcome questions were placed last (OR 2.05; 95% CI 1.00 to 4.24).
The odds of response increased by about half when: using a shorter questionnaire (OR 1.58; 95% CI 1.40 to 1.78); contacting participants before sending questionnaires (OR 1.36; 95% CI 1.23 to 1.51; I2 = 87%); incentives were given with questionnaires (i.e. unconditional) rather than when given only after participants had returned their questionnaire (i.e. conditional on response) (OR 1.53; 95% CI 1.35 to 1.74); using personalised SMS reminders (OR 1.53; 95% CI 0.97 to 2.42); using a special (recorded) delivery service (OR 1.68; 95% CI 1.36 to 2.08; I2 = 87%); using electronic reminders (OR 1.60; 95% CI 1.10 to 2.33); using intensive follow‐up (OR 1.69; 95% CI 0.93 to 3.06); using a more interesting/salient questionnaire (OR 1.73; 95% CI 1.12 to 2.66); and when mentioning an obligation to respond (OR 1.61; 95% CI 1.16 to 2.22). The odds of response also increased with: non‐monetary incentives (OR 1.16; 95% CI 1.11 to 1.21; I2 = 80%); a larger monetary incentive (OR 1.24; 95% CI 1.15 to 1.33); a larger non‐monetary incentive (OR 1.15; 95% CI 1.00 to 1.33); when a pen was included (OR 1.44; 95% CI 1.38 to 1.50); using personalised materials (OR 1.15; 95% CI 1.09 to 1.21; I2 = 57%); using a single‐sided rather than a double‐sided questionnaire (OR 1.13; 95% CI 1.02 to 1.25); using stamped return envelopes rather than franked return envelopes (OR 1.23; 95% CI 1.13 to 1.33; I2 = 69%), assuring confidentiality (OR 1.33; 95% CI 1.24 to 1.42); using first‐class outward mailing (OR 1.11; 95% CI 1.02 to 1.21); and when questionnaires originated from a university (OR 1.32; 95% CI 1.13 to 1.54).
The odds of response were reduced when the questionnaire included questions of a sensitive nature (OR 0.94; 95% CI 0.88 to 1.00).
Electronic
We found 88 eligible trials that evaluated over 30 different ways of increasing response to electronic questionnaires. We found substantial heterogeneity amongst trial results in half of the strategies. The odds of response tripled when: using a brief letter rather than a detailed letter (OR 3.26; 95% CI 1.79 to 5.94); and when a picture was included in an email (OR 3.05; 95% CI 1.84 to 5.06; I2 = 19%).
The odds of response almost doubled when: using monetary incentives (OR 1.88; 95% CI 1.31 to 2.71; I2 = 79%); and using a more interesting topic (OR 1.85; 95% CI 1.52 to 2.26). The odds of response increased by half when: using non‐monetary incentives (OR 1.60; 95% CI 1.25 to 2.05); using shorter e‐questionnaires (OR 1.51; 95% CI 1.06 to 2.16; I2 = 94%); and using a more interesting e‐questionnaire (OR 1.85; 95% CI 1.52 to 2.26). The odds of response increased by a third when: offering survey results as an incentive (OR 1.36; 95% CI 1.16 to 1.59); using a white background (OR 1.31; 95% CI 1.10 to 1.56); and when stressing the benefits to society of response (OR 1.38; 95% CI 1.07 to 1.78; I2 = 41%).
The odds of response also increased with: personalised e‐questionnaires (OR 1.24; 95% CI 1.17 to 1.32; I2 = 41%); using a simple header (OR 1.23; 95% CI 1.03 to 1.48); giving a deadline (OR 1.18; 95% CI 1.03 to 1.34); and by giving a longer time estimate for completion (OR 1.25; 95% CI 0.96 to 1.64).
The odds of response were reduced when: "Survey" was mentioned in the e‐mail subject (OR 0.81; 95% CI 0.67 to 0.97); when the email or the e‐questionnaire was from a male investigator, or it included a male signature (OR 0.55; 95% CI 0.38 to 0.80); and by using university sponsorship (OR 0.84; 95%CI 0.69 to 1.01).
The odds of response using a postal questionnaire were over twice those using an e‐questionnaire (OR 2.33; 95% CI 2.25 to 2.42; I2 = 98%). Response also increased when: providing a choice of response mode (electronic or postal) rather than electronic only (OR 1.76 95% CI 1.67 to 1.85; I2 = 97%); and when administering the e‐questionnaire by computer rather than by smartphone (OR 1.62 95% CI 1.36 to 1.94).
Authors' conclusions
Researchers using postal and electronic questionnaires can increase response using the strategies shown to be effective in this Cochrane review.
Plain language summary
How can response to postal or web questionnaires be increased?
Key messages
Response to questionnaires can be increased by contacting people before they are sent a questionnaire;
Response to questionnaires can be increased by making questionnaires, letters, and emails more personal, and preferably kept short;
Response to questionnaires can be increased by giving an incentive, for example, a small amount of money, or a non‐monetary incentive such as a pen.
Why is response to questionnaires important?
Postal and electronic questionnaires are a relatively inexpensive way to collect information from people for research purposes. If people do not reply (so called ’non‐responders’), the research results will tend to be less accurate.
What did we want to find out?
We wanted to find effective ways to increase response to postal and electronic questionnaires.
What did we do? We searched for studies that examined any way of increasing questionnaire response.
We summarised the results of the studies.
What did we find?
A very large amount of research has been done to try to identify ways to increase response, and we have included 758 studies in this Cochrane methodology review update. The studies included a wide range of people asked to complete a questionnaire, from patients, doctors, university students, and professors, to marketing managers, accountants, and grocery store managers.
We found that response will be increased by contacting people before they are sent a questionnaire. We also found that response to postal questionnaires will be increased if they are sent by a university. Response can also be increased by giving an incentive, for example, a small amount of money, or a non‐monetary incentive such as a pen. Response may be higher using a postal questionnaire rather than an electronic one, or by providing a choice of response modes (electronic or postal). Response can be increased by making questionnaires, letters, and emails more personal, and preferably kept short.
What are the limitations of the evidence?
We had to exclude some studies because we could not confirm that they were free from bias.
How up‐to‐date is this evidence?
This review updates our previous review. The evidence is up‐to‐date to December 2021.
Background
Self‐administered questionnaires are widely used to collect data in epidemiological research (Van Gelder 2010). When collecting information from large, geographically dispersed populations, a self‐administered questionnaire, delivered by post or electronically, is often the only financially viable option. Non‐response to questionnaires reduces the effective sample size and can introduce bias (Armstrong 1995). This review updates our previous version, which was published in 2009 based on searches performed in Feb 2008 (Edwards 2009).
Description of the methods being investigated
A previous review (Yammarino 1991) suggested that repeated contacts (e.g. preliminary notification and follow‐up), appeals in letters, inclusion of a return envelope, types of postage, monetary incentives, and shorter questionnaires can increase response.
How these methods might work
Some methods (e.g. a shorter questionnaire or inclusion of a return envelope) might reduce the burden faced by individuals when completing and returning a questionnaire, leading to an increase in response. Other methods (e.g. incentives) might induce a sense of reciprocity in individuals such that they will complete and return a questionnaire in return for benefits received (Molm 2010).
Why it is important to do this review
The identification of effective strategies to increase response to postal and electronic questionnaires will help to maintain power and reduce the risk of bias in study results, thus improving the quality of epidemiological research.
Objectives
To identify effective strategies to increase response to postal and electronic questionnaires.
Methods
Criteria for considering studies for this review
Types of studies
All unconfounded randomised trials of methods designed to increase response to postal or electronic questionnaires were eligible. A postal questionnaire was defined as a questionnaire that is delivered to a person’s home or work address by a distribution system. This includes questionnaires delivered by any postal service, including internal organisational mail and those hand‐delivered to a person’s address; It does not include questionnaires distributed at, for example, a shop or in a doctor’s office. An electronic questionnaire was defined as a questionnaire that is delivered electronically by email or by SMS and includes those administered online over the internet.
Types of data
Any population (e.g. patients or healthcare providers, and including any participants of non‐health studies) were eligible.
Types of methods
Any methods designed to increase response to postal or electronic questionnaires were eligible. Strategies requiring telephone contact as a follow‐up technique were included but those requiring home visits were not.
Types of outcome measures
Primary outcomes
Proportion of completed, or partially completed postal questionnaires returned after all mailings.
Proportion of participants completing or submitting the online questionnaire.
Secondary outcomes
Proportion of completed, or partially completed questionnaires returned after the first mailing.
Proportion of participants logging in or clicking the hyperlink to visit the online questionnaire.
Search methods for identification of studies
Electronic searches
We identified trials by searching 14 electronic bibliographic databases. We ran these searches in December 2021 and have agreed with Cochrane Methodology that the search should not be updated further after this time. This is because the very large number of reports identified in the December 2021 search and the stability of our overall conclusions means that updating our searches would be of much less relevance than it would be for Cochrane Reviews focusing on clinical questions.
Searching other resources
We handsearched two journals (Public Opinion Quarterly, from 1960 to 1998; American Journal of Epidemiology, from 1948 to 1999). We also searched the reference lists of all identified trials, the reference lists of relevant meta‐analyses, and contacted the authors of the included trials. Full details of the search strategies used for all review versions are illustrated in Appendix 1.
Data collection and analysis
Selection of studies
Two authors independently examined the titles, abstracts and keywords of all records identified from the electronic searches. We obtained full‐text articles (where available) of all selected abstracts and used an eligibility form to determine final study selection. We resolved any disagreements through discussion.
Data extraction and management
Two authors independently extracted data from eligible reports using a standard pro forma, with disagreements resolved by a third author. We extracted data on the type of intervention evaluated, the numbers randomised to intervention or control groups, the quality of allocation concealment, the types of participants, and the materials and follow‐up methods used. Two outcomes were used for each method of delivery to estimate the effect of each intervention on the questionnaire response. For postal, the proportion of questionnaires returned after the first mailing, and the proportion returned after all follow‐up contacts were measured. For electronic, the proportion of participants logging‐in or clicking the hyperlink to visit the online questionnaire, and the proportion of participants completing or submitting the online questionnaire were measured. We excluded trials in which we could not confirm that random allocation had been used to allocate participants. For this 2023 update, we used the online screening and data extraction tool in Covidence and then exported the data from Covidence into a spreadsheet for entry into Review Manager 5 (Review Manager 2020).
As per the original review and in all subsequent updates, we used the first author’s name with the publication year of the reference as the trial identifier. When more than one trial was reported in the paper, we identified these separately by adding letters a, b, c, etc. For example:
Allen 2016 reported two independent experiments, which we have included separately as Allen 2016 and Allen 2016a.
Roszkowski 1990 reported independent replications of the same trial in 14 different populations and we have reported them as Roszkowski 1990a; Roszkowski 1990b; Roszkowski 1990c; Roszkowski 1990d; Roszkowski 1990e; Roszkowski 1990f; Roszkowski 1990g; Roszkowski 1990h; Roszkowski 1990i; Roszkowski 1990j; Roszkowski 1990k; Roszkowski 1990l; Roszkowski 1990m; Roszkowski 1990n.
Gibson 1999 randomised participants to different monetary incentives and reported the results separately for a sample of Medicaid participants (Gibson 1999a) and for a sample of Basic Health Plan participants (Gibson 1999b). All non‐respondents were randomised to a reminder sent using either Certified postal delivery or standard postal delivery (Gibson 1999c).
Assessment of risk of bias in included studies
In the original review version and in the prior update versions (Edwards 2003; Edwards 2007; Edwards 2009), we focused on the integrity of allocation concealment and two authors independently scored methodological quality on the scale used by Schulz (Schulz 1995) as shown below, assigning 'A' to best quality and 'C' to poorest quality:
A ‐ trials deemed to have taken adequate measures to conceal allocation (i.e. central randomisation; computer‐generated address labels; or other description that contained elements that would ensure concealment);
B ‐ trials in which the authors either did not report an allocation concealment approach at all or reported an approach that did not fall into one of the other categories;
C‐ trials in which concealment was inadequate (such as alternation or reference to case record numbers or to dates of birth).
Where the methods used to conceal allocation were not clearly reported, the study authors were contacted, if possible, for clarification. We then compared the scores allocated and resolved differences by discussion. For the current third update version, the risk of bias judgements from the original review and its subsequent updates were carried over (Edwards 2003; Edwards 2007; Edwards 2009), and two authors used the Cochrane Collaboration’s tool for assessing the risk of bias (Higgins 2011) to assess the risk of bias for each newly added study as 'high', 'low', or 'unclear' risk of bias for the seven domains below:
Sequence generation;
Allocation concealment;
Blinding of participants and personnel;
Blinding of outcome assessment;
Incomplete outcome data;
Selective reporting;
Other sources of bias.
We reported the results relating to allocation concealment in all the studies included in this update, and results relating to the other domains for the newly added studies only.
Measures of the effect of the methods
We classified and analysed methods under broad strategies to increase questionnaire response, for example: Incentives ‐ What are participants offered? (e.g. monetary incentive vs. no incentive, unconditional incentive vs. conditional incentive, incentive with first vs. subsequent mailing); Appearance ‐ How does the questionnaire look? (e.g. more personalised vs. less, teaser on envelope vs. none); Delivery ‐ How are the questionnaires received or returned? (e.g. stamped vs. franked outward envelope, certified/special delivery vs. regular outward mailing); Contact ‐ Methods and number of requests for participation (e.g. pre‐contact vs. no pre‐contact, follow‐up vs. no follow‐up); Content ‐ Nature and style of questions (e.g. sensitive questions vs. no/fewer/less sensitive questions asked, demographic items first vs. last, horizontal vs. vertical orientation of response options); Origin ‐ Who sent the questionnaire? (e.g., University sponsor/source vs. other, sent or signed by more vs. less senior/well‐known person); Communication ‐ What are participants told? (e.g. assurance of confidentiality vs. none, participants told completion time 10 mins vs. 30 mins); Length ‐ How long is the questionnaire? (e.g. shorter vs. longer questionnaire, double postcard vs. one page).
In trials with factorial designs, we classified methods under two or more strategies. When methods were evaluated at more than two levels (e.g. highly, moderately and slightly personalised questionnaires), we combined the upper levels, creating a dichotomy. For example, we compared response to the least personalised questionnaire with the combined response to the moderately and highly personalised questionnaires. Monetary incentives were defined as any incentive that could be used by participants as money (e.g. cash). Incentives such as a donation to charity, entrance into a lottery, or a gift (e.g. a pen) were classified as ’non‐monetary’ incentives.
For each included study, we calculated an odds ratio and its 95% confidence interval as the measure of the effect of the method to increase questionnaire response.
Unit of analysis issues
In the small minority of studies that had used a cluster‐randomised design, we did not adjust the results to allow for clustering, but we noted that these were at risk of ‘Other sources of bias’.
Dealing with missing data
We wrote to the authors of reports where required information was missing. See Data extraction and management.
Assessment of heterogeneity
We assessed heterogeneity amongst trial odds ratios using a Chi‐squared test at a 5% significance level, and the degree of inconsistency between trial results was quantified using the I2 statistic (Higgins 2003). The I2 statistic measures the percentage of variation across studies, which is due to heterogeneity. We used the following categories for our interpretation of the I2 statistic (Higgins 2022):
0‐40% might not be important;
30‐60% moderate heterogeneity;
50‐90% substantial heterogeneity;
75‐100% considerable heterogeneity.
Assessment of reporting biases
We assessed evidence for small study bias (such as reporting bias) using Egger’s weighted regression method and Begg’s rank correlation test and funnel plots.
Data synthesis
For each of the broad strategies to increase questionnaire response, we estimated pooled odds ratios in Review Manager 2020 using a random‐effects model. We calculated 95% confidence intervals and two‐sided P values for each outcome.
Subgroup analysis and investigation of heterogeneity
As per our earlier review versions (Edwards 2003; Edwards 2007; Edwards 2009), no subgroup analyses or meta‐regressions were planned/performed.
Sensitivity analysis
As per our earlier review versions (Edwards 2003; Edwards 2007; Edwards 2009), no sensitivity analyses were planned/performed.
Results
Description of studies
Results of the search
For this update: of 92,453 identified abstracts and titles, we removed duplicates and screened 68,193 records/references for eligibility for inclusion. We selected 395 potentially eligible references for independent eligibility assessment of the full‐text reports. After screening full‐text reports, 114 were excluded (reasons for exclusion are summarised in Characteristics of excluded studies). Of the remaining 281 records, 32 were subsequently found to be duplicates, and 26 required further contact with the authors and are listed in Characteristics of studies awaiting classification (also lists the 23 studies awaiting classification from the previous update, Edwards 2009).
Therefore, our updated search identified a total of 223 full‐text records reporting on 245 new trials, bringing the total number of included trials to 758 (513 included in the previous update, Edwards 2009) (Characteristics of included studies).
Included studies
Postal questionnaires
We have identified a total of 670 eligible trials that evaluated over 100 different strategies for increasing response to postal questionnaires. See Characteristics of included studies for further details.
Electronic questionnaires
We have identified a total of 88 eligible trials that evaluated over 30 different strategies for increasing response to electronic questionnaires. See Characteristics of included studies for further details.
Excluded studies
From the latest updated search, we excluded 114 studies: 73 were not a randomised trial, 34 did not use a postal questionnaire, 6 were confounded trials, and 1 was a trial protocol. See Characteristics of excluded studies for further details (also lists the reasons for excluding 87 studies from the previous update, Edwards 2009).
Risk of bias in included studies
See Figure 1 for our risk of bias assessments on the domain 'allocation concealment' in all the included studies in this update, and results relating to the other domains for the newly added studies only.
1.
Allocation
Of the 513 previously identified trials, allocation concealment was classified as C (inadequate) in 76 trials, A (adequate) in 83 trials, and as B (unclear) in the remaining trials. Of the 245 newly added trials, we judged five trials to be at high risk of bias, 112 trials to be at low risk of bias, and there was unclear risk of bias in the remaining trials.
For sequence generation, of the 245 newly added trials, we judged five trials to be at high risk of bias, 110 trials to be at low risk of bias, and there was unclear risk of bias in the remaining trials.
Blinding
Of the 245 newly added trials, participants were not blinded to the intervention in 131 trials. No outcomes were assessed on the participants in any of the included trials (only the counts of responses in the experimental and control groups were reported), and so blinding of outcome assessors was not a risk of bias in any of the newly added trials.
Incomplete outcome data
Of the 245 newly added trials, exclusions were not reported in 34 trials. The remaining trials were at low risk of bias due to follow‐up and exclusions.
Selective reporting
Of the 245 newly added trials, 235 trials reported outcomes in full.
Other potential sources of bias
Of the 245 newly added trials, seven were judged to be at a ‘high’ risk of bias due to results not being adjusted for clustering.
Effect of methods
Table 1 presents a summary of the main findings of this review update.
1. Summary of main results.
| Strategy | Delivery method | No. of studies (no. of participants) | Effect size |
| Monetary incentive | Postal | 111 (226,209) | OR 1.86 (95% CI 1.73 to 1.99) |
| Electronic | 5 (6446) | OR 1.88 (95% CI 1.31 to 2.71) | |
| Telephone reminder | Postal | 4 (15,143) | OR 1.96 (95% CI 1.03 to 3.74) |
| Shorter questionnaire | Postal | 72 (84,954) | OR 1.58 (95% CI 1.40 to 1.78) |
| Electronic | 5 (12,325) | OR 1.51 (95% CI 1.06 to 2.16) | |
| Contact participants before sending questionnaires | Postal | 59 (89,146) | OR 1.36 (95% CI 1.23 to 1.51) |
| Unconditional incentive | Postal | 35 (48,850) | OR 1.53 (95% CI 1.35 to 1.74) |
| Electronic | 3 (1401) | OR 1.08 (95% CI 0.77 to 1.50) | |
| Personalised SMS reminder | Postal | 2 (901) | OR 1.53 (95% CI 0.97 to 2.42) |
| Special delivery service (e.g. recorded, registered, or certified delivery) | Postal | 19 (30,492) | OR 1.68 (95% CI 1.36 to 2.08) |
| Electronic reminder (e.g. SMS or email) | Postal | 2 (582) | OR 1.60 (95% CI 1.10 to 2.33) |
| Intensive follow‐up (e.g. questionnaires at 1, 6 and 12 months) | Postal | 1 (431) | OR 1.69 (95% CI 0.93 to 3.06) |
| More ’interesting’ or high salient questionnaire (e.g. asking questions particularly relevant to the study participants) | Postal | 4 (6491) | OR 1.73 (95% CI 1.12 to 2.66) |
| Electronic | 1 (2176) | OR 1.85 (95% CI 1.52 to 2.26) | |
| Mention an obligation to respond | Postal | 3 (600) | OR 1.61 (95% CI 1.16 to 2.22) |
| Non‐monetary incentive (e.g. Scratch‐card, donation to charity, offer of study results, candy, etc.) | Postal | 146 (277,802) | OR 1.16 (95% CI 1.11 to 1.21) |
| Electronic | 16 (38,901) | OR 1.60 (95% CI 1.25 to 2.05) | |
| Larger monetary incentive | Postal | 50 (137,457) | OR 1.24 (95% CI 1.15 to 1.33) |
| Pen included with questionnaire | Postal | 14 (46,096) | OR 1.32 (95% CI 1.14 to 1.53 |
| Offering study results as an incentive | Electronic | 2 (2884) | OR 1.36 (95% CI 1.16 to 1.59) |
| Personalised materials | Postal | 75 (98,285) | OR 1.15 (95% CI 1.09 to 1.21) |
| Electronic | 12 (48,910) | OR 1.24 (95% CI 1.17 to 1.32) | |
| White background in the email compared to black | Electronic | 1 (6090) | (OR 1.31; 95% CI 1.10 to 1.56) |
| Simple header | Electronic | 1 (5075) | OR 1.23 (95% CI 1.03 to 1.48) |
| Single‐sided questionnaire | Postal | 5 (9383) | OR 1.13 (95% CI 1.02 to 1.25) |
| Stamped return envelope | Postal | 28 (55,550) | OR 1.23 (95% CI 1.13 to 1.33) |
| Assurance of confidentiality | Postal | 1 (25,000) | OR 1.33 (95% CI 1.24 to 1.42) |
| First‐class postage | Postal | 2 (8300) | OR 1.11 (95% CI 1.02 to 1.21) |
| University sponsorship | Postal | 14 (21,628) | OR 1.32 (95% CI 1.13 to 1.54) |
| Electronic | 2 (3845) | OR 0.84 (95% CI 0.69 to 1.01) | |
| Stressing benefits to society | Electronic | 3 (3536) | OR 1.38 (95% CI 1.07 to 1.78) |
| Giving a deadline | Electronic | 1 (8586) | OR 1.18 (95% CI 1.03 to 1.34) |
| Telling participants it would take 30 minutes to complete compared with telling them that it would take 10 mins | Electronic | 1 (2358) | OR 1.25 (95% CI 0.96 to 1.64) |
| “Survey” as subject compared to a blank subject line | Electronic | 2 (3845) | OR 0.81 (95% CI 0.67 to 0.97) |
| Including a ’sensitive’ question | Postal | 10 (21,393) | OR 0.94 (95% CI 0.88 to 1.00) |
SMS: Short message service
Incentives ‐ What are participants offered? (Strategies 1‐22)
Postal questionnaires
One hundred and eleven trials (226,209 participants) evaluated the effect of a monetary incentive on questionnaire response. The odds of response were almost doubled using monetary incentives (odds ratio (OR) 1.86; 95% confidence interval (CI) 1.73 to 1.99). There was, however, considerable heterogeneity amongst the trial results (I2 = 85%) (Analysis 1.2). Fifty trials (137,457 participants) evaluated the effect of a larger rather than a smaller monetary incentive on questionnaire response. The odds of response were a quarter higher when a larger monetary incentive was used (OR 1.24; 95% CI 1.15 to 1.33). There was considerable heterogeneity amongst the trial results (I2 = 82%) (Analysis 2.2). Seventeen trials (28,212 participants) evaluated the effect of offering a monetary rather than a non‐monetary incentive on questionnaire response. The odds of response were increased by over half when a monetary incentive rather than a non‐monetary incentive was used (OR 95% CI 1.67; 95% CI 1.47 to 1.90). There was considerable heterogeneity amongst the trial results (I2 = 75%) (Analysis 3.2).
1.2. Analysis.
Comparison 1: Monetary incentive vs. no incentive, Outcome 2: Final response
2.2. Analysis.
Comparison 2: Larger vs. smaller monetary incentive, Outcome 2: Final response
3.2. Analysis.
Comparison 3: Monetary vs. non‐monetary incentive, Outcome 2: Final response
One hundred and forty‐six trials (277,802 participants) evaluated the effect of a non‐monetary incentive (e.g. key‐ring, lottery participation, donation to charity, offer of study results, candy, etc.) on questionnaire response. The odds of response were increased by over a tenth when a non‐monetary incentive was used (OR 1.16; 95% CI 1.11 to 1.21). There was considerable heterogeneity amongst the results of non‐monetary incentive trials (I2 = 80%) (Analysis 4.2). Eleven trials (18,688 participants) evaluated the effect of a larger rather than a smaller non‐monetary incentive on questionnaire response. There was a possibility that using a larger non‐monetary incentive may increase the odds of response (OR 1.15; 95% CI 1.00 to 1.33; P = 0.05). However, there was considerable heterogeneity amongst the trial results (I2 = 77%) (Analysis 5.2).
4.2. Analysis.
Comparison 4: Non‐monetary incentive vs. no incentive, Outcome 2: Final response
5.2. Analysis.
Comparison 5: Larger non‐monetary incentive vs. smaller, Outcome 2: Final response
Thirty‐five trials (48,850 participants) evaluated the timing of incentives on questionnaire response. The odds of response increased by more than a half when incentives were given with questionnaires (i.e. unconditional) rather than when only given after participants had returned their questionnaires (i.e. conditional on response) (OR 1.53; 95% CI 1.35 to 1.74). There was considerable heterogeneity amongst the trial results (I2 = 89%) (Analysis 6.2). Four trials (8942 participants) evaluated the effect of offering an incentive with the first rather than a subsequent mailing. The odds of response were increased by over a tenth when the incentive was offered with the first mailing (OR 1.14; 95% CI 1.03 to 1.26). There was no evidence of heterogeneity amongst the trial results (I2 = 0%) (Analysis 7.2). Thirteen trials (20,052 participants) evaluated the effect of offering survey results as an incentive. There was no evidence for an effect on response of offering the study results (OR 0.91; 95% CI 0.78 to 1.05). There was considerable heterogeneity amongst the trial results (I2 = 76%) (Analysis 8.2).
6.2. Analysis.
Comparison 6: Unconditional incentive vs. conditional, Outcome 2: Final response
7.2. Analysis.
Comparison 7: Incentive with first vs. subsequent mailing, Outcome 2: Final response
8.2. Analysis.
Comparison 8: Offer of survey results vs. no offer, Outcome 2: Final response
Fourteen trials (46,096 participants) evaluated the effect on questionnaire response of sending a pen with the questionnaire compared to sending the questionnaire without a pen. The odds of response were increased by a third when a pen was included (OR 1.32; 95% CI 1.14 to 1.53). There was considerable heterogeneity amongst the trial results (I2 = 89%) (Analysis 9.2). A single trial (6167 participants) evaluated the effect of sending the questionnaire with a more expensive pen compared to sending the questionnaire with a cheaper pen. There was no evidence for an effect on response of sending a questionnaire with a more expensive pen (OR 1.03; 95% CI 0.81 to 1.31) (Analysis 10.2). The same trial (6167 participants) evaluated the effect of sending the questionnaire with a pen in a box compared to sending the questionnaire with an unboxed pen. The odds of response were increased by a tenth when the pen was in a box (OR 1.10; 95% CI 1.00 to 1.22) (Analysis 11.2). A single trial (2342 participants) evaluated the effect of sending a monetary incentive with the follow‐up mailing compared to no incentive with the follow‐up. There was no evidence for an effect on response of sending a monetary incentive with the follow‐up mailing (OR 0.97; 95% CI 0.82 to 1.16) (Analysis 12.2). A single trial (444 participants) evaluated the effect of sending the questionnaire with non‐monetary incentives compared to sending the questionnaire with the promise of making a charitable donation. The odds of response were nearly one half greater with a non‐monetary incentive than with a donation to charity (OR 1.44; 95% CI 0.98 to 2.12) (Analysis 13.1). A single trial (531 participants) evaluated the effect of sending the questionnaire with a cheque incentive that required the participant to give their social security number ID to cash it, compared to sending the questionnaire with a cheque incentive that did not require a social security number ID. There was no evidence for an effect on response when participants were required to give their social security number ID (OR 0.75; 95% CI 0.41 to 1.37) (Analysis 14.1). Eleven trials (19,981 participants) evaluated the effect on questionnaire response via including a study brochure with the questionnaire compared to no brochure. There was no evidence for an effect on response of including a study brochure (OR 0.97; 95% CI 0.83 to 1.13). There was moderate heterogeneity between the trial results (I2 = 64%) (Analysis 15.3). A single trial (303 participants) evaluated the effect of sending a cheque incentive compared to sending the questionnaire with a cashcard (i.e. a reloadable debit card). The odds of response were greater with a cheque than with a cashcard (OR 1.81; 95% CI 1.15 to 2.86) (Analysis 16.2). A single trial (2856 participants) evaluated the effect of sending a monetary incentive comprising multiple banknotes compared to a single note. There was no evidence for an effect on response with multiple banknotes compared to a single note (OR 1.08; 95% CI 0.94 to 1.26) (Analysis 17.2).
9.2. Analysis.
Comparison 9: Pen vs. no pen, Outcome 2: Final Response
10.2. Analysis.
Comparison 10: Cheap pen vs. expensive pen, Outcome 2: Final Response
11.2. Analysis.
Comparison 11: Boxed pen vs. unboxed, Outcome 2: Final Response
12.2. Analysis.
Comparison 12: Monetary incentive with follow‐up vs. no incentive with follow‐up, Outcome 2: Final response
13.1. Analysis.
Comparison 13: Non‐monetary incentive vs. charitable donation, Outcome 1: Final response
14.1. Analysis.
Comparison 14: Cheque incentive requiring ID vs. no ID, Outcome 1: Final response
15.3. Analysis.
Comparison 15: Study brochure vs. no brochure, Outcome 3: Final response
16.2. Analysis.
Comparison 16: Cheque incentive vs. cashcard, Outcome 2: First Response
17.2. Analysis.
Comparison 17: Single cash note vs. multiple notes, Outcome 2: Final Response
Electronic questionnaires
Five trials (6446 participants) evaluated the effect of a monetary incentive on electronic questionnaire response. The odds of response were almost doubled using monetary incentives (OR 1.88; 95% CI 1.31 to 2.71). There was considerable heterogeneity between the trial results (I2 = 79%) (Analysis 1.4). Three trials (3614 participants) evaluated the effect of a monetary rather than a non‐monetary incentive on e‑questionnaire response. There was no evidence for an effect on response of using a monetary rather than a non‐monetary incentive (OR 0.89; 95% CI 0.63 to 1.26). There was considerable heterogeneity between the trial results (I2 = 81%) (Analysis 3.4). Sixteen trials (38,901 participants) evaluated the effect of a non‐monetary incentive (e.g. Amazon gift cards, lottery participation, personal digital assistant, early grade feedback, etc.) on e‐questionnaire response. The odds of response were almost doubled when a non‐monetary incentive was used (OR 1.60; 95% CI 1.25 to 2.05). There was considerable heterogeneity amongst the trial results (I2 = 93%) (Analysis 4.4). Ten trials (37,382 participants) evaluated the effect of a larger rather than a smaller non‐monetary incentive on e‐questionnaire response. There was no evidence for an effect on response of using a larger non‐monetary incentive (OR 1.07; 95% CI 0.87 to 1.32). There was considerable heterogeneity amongst the trial results (I2 = 89%) (Analysis 5.4).
1.4. Analysis.
Comparison 1: Monetary incentive vs. no incentive, Outcome 4: e ‐ Submission
3.4. Analysis.
Comparison 3: Monetary vs. non‐monetary incentive, Outcome 4: e ‐ Submission
4.4. Analysis.
Comparison 4: Non‐monetary incentive vs. no incentive, Outcome 4: e ‐ Submission
5.4. Analysis.
Comparison 5: Larger non‐monetary incentive vs. smaller, Outcome 4: e ‐ Submission
Three trials (1401 participants) evaluated the timing of incentives on e‐questionnaire response. There was no evidence for an effect on response when incentives were given with e‐questionnaires (i.e. unconditional) rather than only given after participants had submitted their e‐questionnaire (i.e. conditional on response) (OR 1.08; 95% CI 0.77 to 1.50) (Analysis 6.4). Two trials (2884 participants) evaluated the effect on e‐questionnaire response of offering survey results as an incentive. The odds of response increased by over a third when an offer of results was used (OR 1.36; 95% CI 1.16 to 1.59) (Analysis 8.3).
6.4. Analysis.
Comparison 6: Unconditional incentive vs. conditional, Outcome 4: e ‐ Submission
8.3. Analysis.
Comparison 8: Offer of survey results vs. no offer, Outcome 3: e ‐ Submission
One trial (2233 participants) evaluated the effect of immediate notification of lottery results compared to delayed notification on e‐questionnaire response. The odds of response were increased by almost half when lottery results were immediately notified (OR 1.37; 95% CI 1.13 to 1.65) (Analysis 20.1). Two trials (4721 participants) evaluated the effect of higher denominations of currencies in a monetary lottery compared to lower denominations on e‐questionnaire response. There was no evidence for an effect on response of offering higher denominations in a monetary lottery (OR 1.00; 95% CI 0.87 to 1.14) (Analysis 18.1). One trial (1061 participants) evaluated the combined effect of conditional and unconditional incentives on e‐questionnaire response compared to conditional incentives alone. There was no evidence for an effect on response of using the combined incentives (OR 1.19; 95% CI 0.92 to 1.54) (Analysis 19.1). Another trial (3000 participants) evaluated the combined effect of conditional and unconditional incentives on e‐questionnaire response compared to unconditional incentives alone. This trial found evidence that response was increased using the combined incentives (OR 1.23; 95% CI 1.06 to 1.44) (Analysis 21.4). A single trial (130 participants) evaluated the effect on response to a smart‐phone daily diary app that included a game that gave in‐game rewards when a daily diary was completed. There was no evidence that the inclusion of the game increased response (OR 0.51; 95% CI 0.19 to 1.40) (Analysis 22.2)
20.1. Analysis.
Comparison 20: Immediate notification of lottery results vs. delayed notification, Outcome 1: e ‐ Submission
18.1. Analysis.
Comparison 18: Higher denominations in monetary lottery incentives vs. lower, Outcome 1: e ‐ Submission
19.1. Analysis.
Comparison 19: Unconditional and conditional incentives vs. conditional incentives, Outcome 1: e ‐ Submission
21.4. Analysis.
Comparison 21: Unconditional and conditional incentives vs. unconditional incentive, Outcome 4: e ‐ Submission
22.2. Analysis.
Comparison 22: Electronic with game vs. no game, Outcome 2: Final Response
Appearance ‐ How do the questionnaires look? (Strategies 23‐60)
Postal questionnaires
Seventy‐four trials (97,674 participants) evaluated the effect on questionnaire response of making questionnaire materials more personal, such as signing letters by hand. The odds of response were increased by more than a tenth with a more personalised approach to participants (OR 1.15; 95% CI 1.09 to 1.21). There was, however, considerable heterogeneity amongst the results of these trials (I2 = 57%) (Analysis 23.2). Fourteen trials (15,006 participants) evaluated the effect of cover letters bearing a handwritten signature compared to those that are typed or scanned or printed. The odds of response increased by a quarter using handwritten signatures (OR 1.24; 95% CI 1.08 to 1.41) (Analysis 24.2). Nine trials (6030 participants) evaluated the effect of handwritten address labels compared to computer‐printed labels. The odds of response increased by a quarter when using the handwritten labelled questionnaire (OR 1.23; 95% CI 1.09 to 1.37) (Analysis 25.2). Three trials (1364 participants) evaluated the presence of a signature within the questionnaire. There was some evidence for an effect on response of using a signature within the questionnaire (OR 1.35; 95% CI 1.04 to 1.76) (Analysis 26.2).
23.2. Analysis.
Comparison 23: More vs. less personalised, Outcome 2: Final response
24.2. Analysis.
Comparison 24: Handwritten vs. typed/facsimile/scanned/printed signature on covering letter, Outcome 2: Final response
25.2. Analysis.
Comparison 25: Handwritten address vs. computer‐printed, Outcome 2: Final response
26.2. Analysis.
Comparison 26: Signed vs. unsigned, Outcome 2: Final response
Ten trials (5297 participants) evaluated the effect of including an identifying feature, such as a participant’s name or identity number, on questionnaire response. There was no evidence for an effect on response of using an identifying feature (OR 1.03; 95% CI 0.81 to 1.32). There was considerable heterogeneity between the trial results (I2 = 71%) (Analysis 27.2). One trial (741 participants) evaluated the effect on response of an identifying number on the returned questionnaire compared with another identifier. There was no evidence for an effect on response of using an identifying number (OR 1.00; 95% CI 0.68 to 1.46) (Analysis 28.2).
27.2. Analysis.
Comparison 27: Identifying feature on return vs. none, Outcome 2: Final response
28.2. Analysis.
Comparison 28: Identifying number on return vs. other identifier, Outcome 2: Final response
Fifteen trials (43,754 participants) evaluated the effect on response of using questionnaires printed on coloured paper. There was no evidence for an effect on response of using a coloured questionnaire (OR 1.03; 95% CI 0.98 to 1.09) (Analysis 29.2). Three trials (7040 participants) evaluated the effect of using coloured ink, compared with black or blue ink, on questionnaire response. There was no evidence for an effect on response of using coloured ink (OR 1.16; 95% CI 0.95 to 1.42). There was moderate heterogeneity between the trial results (I2 = 67%) (Analysis 30.2). Two trials (2356 participants) evaluated the effect of a coloured letterhead compared to a black and white letterhead. There was no evidence for an effect on response of using a coloured letterhead (OR 1.08; 95% CI 0.91 to 1.28) (Analysis 31.2). A single trial (320 participants) evaluated the effect of an illustration on the cover of the questionnaire largely in black, versus largely in white. The odds of response increased by more than a half when using an illustration on the cover of the questionnaire that was largely in black (OR 1.62; 95% CI 1.04 to 2.53) (Analysis 32.1). Three trials (5681 participants) evaluated the effect on response of using a booklet compared to stapled pages. There was no evidence for an effect on response of using a booklet (OR 1.10; 95% CI 0.99 to 1.23) (Analysis 33.2). Two trials (2145 participants) evaluated the effect of the paper size of the questionnaire on response. There was no evidence for an effect on response of using a large paper size (OR 0.88; 95% CI 0.56 to 1.39) (Analysis 34.2). A single trial (176 participants) evaluated the effect on questionnaire response of printing the questionnaire using dot‐matrix compared to a letter‐quality print. There was no evidence for an effect of response of using the dot‐matrix print (OR 1.15; 95% CI 0.63 to 2.10) (Analysis 35.1).
29.2. Analysis.
Comparison 29: Coloured vs. white questionnaire, Outcome 2: Final response
30.2. Analysis.
Comparison 30: Coloured vs. standard (black/blue) ink, Outcome 2: Final response
31.2. Analysis.
Comparison 31: Coloured vs. black & white letterhead, Outcome 2: Final response
32.1. Analysis.
Comparison 32: Illustration on cover of q'aire largely in black vs. largely in white, Outcome 1: Final response
33.2. Analysis.
Comparison 33: Folder or booklet vs. stapled pages, Outcome 2: Final response
34.2. Analysis.
Comparison 34: Large paper size vs. small, Outcome 2: Final response
35.1. Analysis.
Comparison 35: Dot matrix print vs. letter quality print, Outcome 1: Final response
Three trials (3372 participants) evaluated the effect of the questionnaire being printed on a high quality or thicker paper, compared to standard quality or thin paper. There was no evidence for an effect on response of using a high quality or a thicker paper (OR 0.83; 95% CI 0.68 to 1.02) (Analysis 36.1). Five trials (9383 participants) evaluated the effect of using a single‐sided questionnaire compared to a double‐sided questionnaire. The odds of response increased by a tenth when a single‐sided questionnaire was used (OR 1.13; 95% CI 1.02 to 1.25) (Analysis 37.2). One trial (650 participants) evaluated the effect on response of using a larger font compared to a smaller font. There was no evidence for an effect on response of using larger fonts (OR 1.26; 95% CI 0.87 to 1.82) (Analysis 38.1). A single trial (1000 participants) compared the presence of a study logo on several items in the mailing package to its presence in the questionnaire only. There was no evidence for an effect on response of using the study logo on several items in the mailing package (OR 0.92; 95% CI 0.72 to 1.18) (Analysis 39.1). Five trials (3956 participants) evaluated the effect of the presence of a picture in the questionnaire. There was no evidence for an effect on response of using a picture (OR 1.03; 95% CI 0.70 to 1.51) (Analysis 40.2). One trial (280 participants) evaluated the effect on response of including a cartoon in the questionnaire. There was no evidence for an effect on response of including a cartoon (OR 1.00; 95% CI 0.62 to 1.62) (Analysis 42.1). Two trials (2904 participants) evaluated the effect on response of questionnaires having a more professional design compared with a standard design. There was no evidence for an effect on response of questionnaires having a more professional design (OR 1.00; 95% CI 0.58 to 1.72). There was considerable heterogeneity between the trial results (I2 = 88%) (Analysis 43.2).
36.1. Analysis.
Comparison 36: Questionnaire printed on high vs. standard quality paper or thick paper vs. thin, Outcome 1: Final response
37.2. Analysis.
Comparison 37: Single vs. double‐sided questionnaire, Outcome 2: Final response
38.1. Analysis.
Comparison 38: Large font size vs. small, Outcome 1: Final response
39.1. Analysis.
Comparison 39: Study logo on several items in the mailing package vs. on questionnaire only, Outcome 1: Final response
40.2. Analysis.
Comparison 40: Picture of researcher/images vs. none, Outcome 2: Final response
42.1. Analysis.
Comparison 42: Cartoons included vs. not included, Outcome 1: Final response
43.2. Analysis.
Comparison 43: Professional design vs. standard, Outcome 2: Final outcome
Two trials (901 participants) evaluated the effect on questionnaire response of sending personalised SMS reminders to non‐respondents compared with standard SMS reminders. There was some evidence that the odds of response were increased with personalised SMS reminders (OR 1.53; 95% CI 0.97 to 2.43) (Analysis 44.2). A single trial (231 participants) evaluated the effect on response of using "Action Required" as the subject line of an email reminder compared with “Questionnaire reminder” as the subject. There was no evidence for an effect on response of using "Action Required" as the subject line (OR 0.61; 95% CI 0.23 to 1.63) (Analysis 45.2). Two trials (3895 participants) evaluated the effect on response of including a message about an incentive on the envelope compared with none. There was no evidence for an effect on response by including a message (OR 0.91; 95% CI 0.80 to 1.04) (Analysis 46.2). A single trial (1569 participants) evaluated the effect on response of a health message on the envelope compared with a monetary incentive message. There was no evidence that response differed between the health or the monetary incentive messages (OR 1.05; 95% CI 0.86 to 1.29) (Analysis 47.2). Five trials (23,621 participants) evaluated the effect of including a ‘teaser’ on the envelope. There was no evidence for an effect on response when a teaser was used (OR 1.08; 95% CI 0.95 to 1.22) There was moderate heterogeneity amongst the trial results (I2 = 37%) (Analysis 48.2). Two trials (1678 participants) evaluated the effect of using a more readable/concise/info‐mapped letter on response. There was no evidence for an effect on response of using a more readable/concise/info‐mapped letter (OR 0.88; 95% CI 0.72 to 1.09) (Analysis 49.2). A single trial (517 participants) evaluated the effect on response of a study logo sticker on the envelope compared with no sticker. There was no evidence that response was increased with the sticker (OR 1.06; 95% CI 0.75 to 1.49) (Analysis 50.1).
44.2. Analysis.
Comparison 44: Personalised SMS reminder vs. standard SMS reminder, Outcome 2: Final Response
45.2. Analysis.
Comparison 45: "Action Required" subject line vs. "Reminder", Outcome 2: Final response
46.2. Analysis.
Comparison 46: Message about incentive on envelope vs. no message, Outcome 2: Final response
47.2. Analysis.
Comparison 47: Health message vs. monetary message, Outcome 2: Final response
48.2. Analysis.
Comparison 48: Teaser on envelope vs. no teaser, Outcome 2: Final response
49.2. Analysis.
Comparison 49: More readable/concise/info mapped letter vs. standard, Outcome 2: Final response
50.1. Analysis.
Comparison 50: Logo sticker on envelope vs. no sticker, Outcome 1: First response
Electronic
Twelve trials (48,910 participants) evaluated the effect on e‐questionnaire response by addressing the salutations in the cover letters accompanying the questionnaires personally, or by giving a touch of personalisation to the cover letters. The odds of response were increased by about a quarter when a personalised approach was adopted (OR 1.24; 95% CI 1.17 to 1.32). There was moderate heterogeneity between trial results (I2 = 41%) (Analysis 23.4). Two trials (720 participants) evaluated the effect of the presence of a picture in the email. The odds of response tripled when a picture was sent in the email (OR 3.05; 95% CI 1.84 to 5.06) (Analysis 40.3). The same trials (520 participants) evaluated the effect of response when a more attractive picture was used compared to a less attractive picture. There was little evidence for an effect on response of using a more attractive picture (OR 3.44; 95% CI 0.72 to 16.49) (Analysis 41.1).
23.4. Analysis.
Comparison 23: More vs. less personalised, Outcome 4: e ‐ Submission
40.3. Analysis.
Comparison 40: Picture of researcher/images vs. none, Outcome 3: e ‐ Submission
41.1. Analysis.
Comparison 41: Attractive vs. less attractive picture, Outcome 1: e ‐ Submission
Two trials (6152 participants) evaluated the presence of a topic in the subject line of the email compared to a blank subject line. There was no evidence for an effect on response of using a topic in the subject line (OR 0.84; 95% CI 0.71 to 1.01) (Analysis 51.2). Two trials (3845 participants) evaluated the presence of “Survey” as the subject line compared to a blank subject line. The odds of response decreased by a fifth when “Survey” was mentioned in the subject line (OR 0.81; 95% CI 0.67 to 0.97) (Analysis 52.2).
51.2. Analysis.
Comparison 51: Subject line vs. blank, Outcome 2: e ‐ Submission
52.2. Analysis.
Comparison 52: "Survey" subject line vs. blank, Outcome 2: e ‐ Submission
One trial (6090 participants) evaluated the effect of sending emails in text‐file format compared to HTML. There was no evidence for an effect on response of using text file format (OR 1.00; 95% CI 0.84 to 1.19) (Analysis 53.1). The same trial (6090 participants) evaluated the presence of using a white background in the email compared to a black background. The odds of response increased by over a quarter when a white background was used (OR 1.31; 95% CI 1.10 to 1.56) (Analysis 54.1). The same trial (6090 participants) also evaluated the effect of including a header compared to no header in the email. There was no evidence for an effect on response of using a header (OR 1.13; 95% CI 0.90 to 1.41) (Analysis 55.1). The same trial (5075 participants) also evaluated the effect of a simple header compared to a complex header. The odds of response increased by almost a quarter when a simple header was used (OR 1.23; 95% CI 1.03 to 1.48) (Analysis 56.1).
53.1. Analysis.
Comparison 53: Text vs. HTML file formats, Outcome 1: e ‐ Submission
54.1. Analysis.
Comparison 54: White background vs. black, Outcome 1: e ‐ Submission
55.1. Analysis.
Comparison 55: Header vs. no header, Outcome 1: e ‐ Submission
56.1. Analysis.
Comparison 56: Simple vs. complex header, Outcome 1: e ‐ Submission
One trial (5413 participants) evaluated the effect of textual presentation of response categories compared to visual presentation of response categories. The odds of response increased by almost a fifth when textual presentation was used (OR 1.19; 95% CI 1.05 to 1.36) (Analysis 57.1). A single trial (517 participants) evaluated the effect on response of formatting a web survey as a single scrollable page compared with multiple pages. There was no evidence for an effect on response of using a single scrollable page (OR 0.93; 95% CI 0.66 to 1.32) (Analysis 58.1). Two trials (3676 participants) evaluated the effect on e‐questionnaire response of an email subject line that emphasised an incentive compared with no such emphasis on the subject. There was no evidence for an effect on response when the email subject emphasised an incentive (OR 2.19; 95% CI 0.58 to 8.27). There was considerable heterogeneity between the trial results (I2 = 97%) (Analysis 59.2). A single trial (2963 participants) evaluated the effect on e‐questionnaire response of an email reminder including humour compared to a standard email. There was no evidence for an effect on response when including humour (OR 1.17; 95% CI 0.99 to 1.38) (Analysis 60.1).
57.1. Analysis.
Comparison 57: Textual presentation of response categories vs. visual presentation, Outcome 1: e ‐ Submission
58.1. Analysis.
Comparison 58: Scrollable web page vs. multiple web pages, Outcome 1: Final response
59.2. Analysis.
Comparison 59: Subject line emphasises incentive vs. no emphasis, Outcome 2: e ‐ Submission
60.1. Analysis.
Comparison 60: Email reminder including humour vs. standard email, Outcome 1: e ‐ Submission
Delivery ‐ How are the questionnaires received or returned? (Strategies 61‐93)
Postal
Six trials (13,964 participants) evaluated the effect on questionnaire response of using stamps on outgoing envelopes compared to franked envelopes. There was no evidence for an effect on response of using stamps on outgoing envelopes (OR 0.95; 95% CI 0.88 to 1.03) (Analysis 61.2). Two trials (8300 participants) evaluated the effect on questionnaire response of using first class compared to other classes of postage. The odds of response were increased by over one‐tenth using first‐class postage (OR 1.11; 95% CI 1.02 to 1.21) (Analysis 62.2).
61.2. Analysis.
Comparison 61: Stamped vs. franked outward envelope, Outcome 2: Final response
62.2. Analysis.
Comparison 62: First vs. second/third class outward mailing, Outcome 2: Final response
Five trials (5461 participants) evaluated the effect on questionnaire response of using commemorative stamps rather than standard stamps on return envelopes. There was no evidence for an effect on response of using commemorative stamps (OR 0.92; 95% CI 0.81 to 1.06) (Analysis 63.2). Nineteen trials (30,492 participants) evaluated the effect on questionnaire response of using a special delivery service (e.g. recorded, registered, or certified delivery), rather than standard delivery. The odds of response increased by more than half when special delivery was used (OR 1.68; 95% CI 1.36 to 2.08). Results were considerably heterogeneous (I2 = 87%) (Analysis 64.2). Twenty‐eight trials (55,550 participants) evaluated the effect on questionnaire response of using a stamped return envelope compared to a pre‐paid business or franked reply envelope. The odds of response increased by a quarter when stamps were used (OR 1.23; 95% CI 1.13 to 1.33). There was moderate heterogeneity between the trial results (I2 = 69%) (Analysis 65.2). One trial (205 participants) evaluated the effect of using priority stamps on return envelopes compared to using a first‐class stamp. The odds of response decreased by more than a half when priority stamps were used (OR 0.26; 95% CI 0.14 to 0.46) (Analysis 66.1). One trial (800 participants) evaluated the effect of using a first‐class stamp on return envelopes compared to a second‐class stamp. There was no evidence for an effect on response of using a first‐class stamp on the return envelope (OR 0.91; 95% CI 0.69 to 1.21) (Analysis 67.1).
63.2. Analysis.
Comparison 63: Commemorative/race‐specific vs. ordinary stamp on return envelope, Outcome 2: Final response
64.2. Analysis.
Comparison 64: Certified/special delivery vs. regular outward mailing, Outcome 2: Final response
65.2. Analysis.
Comparison 65: Stamped return vs. business reply/franked envelope, Outcome 2: Final response
66.1. Analysis.
Comparison 66: Priority stamps vs. first‐class stamps on return envelope, Outcome 1: Final response
67.1. Analysis.
Comparison 67: First vs. second‐class stamp on return envelope, Outcome 1: Final response
A single trial (510 participants) evaluated the use of multiple stamps on return envelopes compared to a single stamp. The odds of response increased by almost half when multiple stamps were used (OR 1.44; 95% CI 1.01 to 2.04) (Analysis 68.1). Four trials (4094 participants) evaluated the effect on questionnaire response of providing any sort of pre‐paid return envelope rather than none. There was no evidence for an effect on response of including pre‐paid envelopes (OR 1.09; 95% CI 0.71 to 1.68). There was considerable heterogeneity amongst the trial results (I2 = 87%) (Analysis 69.2). A single trial (147 participants) evaluated the effect of including a stamped addressed return envelope compared to only including an address label. This trial provided no evidence for an effect on response of using a stamped addressed return envelope (OR 0.86; 95% CI 0.45 to 1.65) (Analysis 70.1).
68.1. Analysis.
Comparison 68: Multiple stamps vs. single stamp on return envelope, Outcome 1: Final response
69.2. Analysis.
Comparison 69: Pre‐paid return envelope vs. not pre‐paid, Outcome 2: Final response
70.1. Analysis.
Comparison 70: Stamped addressed return envelope vs. address label only included, Outcome 1: Final response
Two trials (1140 participants) evaluated the effect on response of sending questionnaires to the participant’s work address rather than to their home address. There was no evidence for an effect on response of sending questionnaires to work addresses (OR 1.16; 95% CI 0.89 to 1.52) (Analysis 71.2). Two trials (11,781 participants) evaluated the effect of using a window envelope on questionnaire response. There was no evidence for an effect on response of using window envelopes (OR 0.96; 95% CI 0.61 to 1.49). There was considerable heterogeneity between the trial results (I2 = 75%) (Analysis 72.2). A single trial (1200 participants) evaluated the effect on questionnaire response of sending the questionnaire in a larger envelope compared to a standard or smaller envelope. There was no evidence for an effect on response of using larger envelopes (OR 0.93; 95% CI 0.74 to 1.17) (Analysis 73.1).
71.2. Analysis.
Comparison 71: Questionnaire sent to work vs. home address, Outcome 2: Final response
72.2. Analysis.
Comparison 72: Window vs. regular envelope, Outcome 2: Final response
73.1. Analysis.
Comparison 73: Q'aire mailed in large vs. standard/small envelope, Outcome 1: Final response
Six trials (9756 participants) evaluated the effect on questionnaire response of using brown envelopes compared to white. There was no evidence for an effect on response of using a brown envelope (OR 1.25; 95% CI 0.86 to 1.80). There was considerable heterogeneity between the trial results (I2 = 92%) (Analysis 181.2). Two trials (1843 participants) evaluated the effect of questionnaires being mailed on Monday compared to being sent on Friday. There was no evidence for an effect on response of sending the questionnaire on Monday (OR 0.84; 95% CI 0.70 to 1.01) (Analysis 74.2). Two trials (2324 participants) evaluated the effect on response of questionnaires being sent one to five weeks after discharge from hospital, compared to being sent after 9 to 14 weeks. There was little evidence for an effect on response of questionnaires being sent sooner after discharge from hospital (OR 2.26; 95% CI 0.69 to 7.37). There was considerable heterogeneity between the trial results (I2 = 83%) (Analysis 76.1).
181.2. Analysis.
Comparison 181: Brown vs. white envelope, Outcome 2: Final response
74.2. Analysis.
Comparison 74: Questionnaire mailed on Monday vs. Friday, Outcome 2: Final response
76.1. Analysis.
Comparison 76: Q'aire sent 1‐5 weeks vs. 9‐14 weeks after hospital discharge, Outcome 1: Final response
One trial (460 participants) evaluated the effect of a questionnaire being received on a Monday, compared to being received on a Friday. There was no evidence for an effect on response of questionnaires being received on a Monday (OR 1.00; 95% CI 0.64 to 1.56) (Analysis 75.1). One trial (1600 participants) evaluated the effect on response of using a padded envelope compared to a priority mail envelope. There was no evidence for an effect on response of using a padded envelope (OR 0.88; 95% CI 0.72 to 1.07) (Analysis 77.1).
75.1. Analysis.
Comparison 75: Questionnaire received on Monday/Tuesday vs. Friday, Outcome 1: Final response
77.1. Analysis.
Comparison 77: Padded envelope vs. priority mail envelope, Outcome 1: First response
A small trial (135 participants) evaluated the effect on response of the questionnaire being hand‐delivered by a person known to the recipient compared to standard postal delivery. The odds of response were more than doubled when the questionnaire was hand‐delivered by a known person (OR 2.60; 95% CI 1.29 to 5.23) (Analysis 78.1). Two trials (937 participants) evaluated the effect on questionnaire response of hand delivery compared to postal delivery. There was no evidence overall that response was increased using hand delivery (OR 1.44; 95% CI 0.50 to 4.15). There was considerable heterogeneity amongst the trial results (I2 = 88%) (Analysis 79.1). One trial (199 participants) evaluated the effect on response of sending a postal questionnaire compared with sending it by fax. The odds of response were almost halved when sending by fax (OR 0.58; 95% CI 0.29 to 1.14) (Analysis 80.2).
78.1. Analysis.
Comparison 78: Hand delivery by known person vs. postal delivery, Outcome 1: Final response
79.1. Analysis.
Comparison 79: Hand delivery vs. postal delivery, Outcome 1: Final response
80.2. Analysis.
Comparison 80: Postal vs. fax, Outcome 2: Final Response
Electronic
Twenty‐seven trials (66,118 participants) evaluated the effect on response of sending a postal questionnaire compared with sending an e‐questionnaire. The odds of response were almost doubled using a postal questionnaire (OR 1.76; 95% CI 1.34 to 2.32). . There was, however, considerable heterogeneity between the trial results (I2 = 98%) (Analysis 81.2). Eight trials (20,909 participants) evaluated the effect of providing a choice of response modes (i.e. postal with optional electronic response) compared to postal only. There was no evidence for an effect on response by providing an optional electronic response mode (OR 0.94; 95% CI 0.86 to 1.02). There was moderate heterogeneity amongst the trial results (I2 = 51%) (Analysis 82.2).
81.2. Analysis.
Comparison 81: Postal vs. electronic, Outcome 2: Final Response
82.2. Analysis.
Comparison 82: Choice (electronic/postal) vs. only postal response, Outcome 2: Final response
Four trials (2958 participants) evaluated the effect on response of sending a postal questionnaire first with electronic follow‐up compared to an e‐questionnaire first with postal follow‐up. There was no evidence for an effect on response of sending a postal questionnaire first (OR 1.19; 95% CI 0.76 to 1.87). There was considerable heterogeneity between the trial results (I2 = 85%) (Analysis 83.2). Ten trials (39,523 participants) evaluated the effect on response of providing a choice of response modes (electronic or postal response) compared to electronic only. Response was increased when providing a choice of response modes (electronic or postal response) compared to electronic only (OR 1.63; 95% CI 1.18 to 2.26). There was considerable heterogeneity between the trial results (I2 = 97%) (Analysis 84.2). A single trial (6188 participants) evaluated the effect on response of asking participants to request their desired type of questionnaire compared to offering a choice of a postal or an e‐questionnaire immediately. The odds of response were one‐half greater when offering the choice of postal or an e‐questionnaire immediately (OR 1.59; 95% CI 1.43 to 1.77) (Analysis 85.2).
83.2. Analysis.
Comparison 83: Postal with electronic follow‐up vs. electronic with postal follow‐up, Outcome 2: Final response
84.2. Analysis.
Comparison 84: Electronic vs. choice (postal/electronic), Outcome 2: Final response
85.2. Analysis.
Comparison 85: Pre‐selected choice vs. choice, Outcome 2: Final response
A single trial (2774 participants) evaluated the effect on response of administering the e‐questionnaire by computer compared to by smartphone. The odds of response were increased when using a computer rather than a smartphone (OR 1.62; 95% CI 1.36 to 1.94) (Analysis 86.2). A single trial (620 participants) evaluated the effect on response of administering the questionnaire by smartphone and Web, compared to by post with email follow‐up contacts. There was no evidence for an effect on response of administering the questionnaire by smartphone and Web (OR 1.02; 95% CI 0.50 to 2.08) (Analysis 87.2). One trial (195 participants) evaluated the effect on response of sending an e‐questionnaire compared with sending it by fax. The odds of response were almost four times greater with an e‐questionnaire than with a fax (OR 3.87; 95% CI 2.0 to 7.49) (Analysis 88.2).
86.2. Analysis.
Comparison 86: Mobile‐based web survey vs. computer, Outcome 2: Completed questionnaire
87.2. Analysis.
Comparison 87: Mobile and web vs. paper and email, Outcome 2: Final Response
88.2. Analysis.
Comparison 88: Electronic vs. fax, Outcome 2: Final Response
A single trial (382 participants) evaluated the effect on response of administering the questionnaire by SMS compared to by post. There was no evidence for an effect on response of administering the questionnaire by SMS (OR 1.19; 95% CI 0.60 to 2.32) (Analysis 89.2). One trial (1943 participants) evaluated the effect of an e‐questionnaire being received on a Monday or Tuesday, compared to being received on a Friday. There was no evidence for an effect on response of e‐questionnaires being received on a Monday or Tuesday (OR 0.96; 95% CI 0.66 to 1.40) (Analysis 75.3). A single trial (21,473 participants) evaluated the effect on response to a Web survey of varying the days on which invitation emails and reminders were sent. The odds of response were greater when fixing the days on which invitation emails and reminders are sent (OR 1.08; 95% CI 1.03 to 1.14) (Analysis 90.2). The same trial evaluated the effect on response to a Web survey using a model to predict the best day on which to send invitation emails and reminders. The odds of response were greater when fixing the days on which invitation emails and reminders were sent (OR 1.05; 95% CI 1.00 to 1.11) (Analysis 91.2).
89.2. Analysis.
Comparison 89: SMS vs. postal, Outcome 2: Final Response
75.3. Analysis.
Comparison 75: Questionnaire received on Monday/Tuesday vs. Friday, Outcome 3: e ‐ Submission
90.2. Analysis.
Comparison 90: Emails and reminders sent on varying vs. fixed days, Outcome 2: Final response
91.2. Analysis.
Comparison 91: Emails and reminders sent on best predicted days vs. fixed days, Outcome 2: Final response
One trial (1999 participants) evaluated the effect on response of sending a postal follow‐up to an e‐questionnaire compared with follow‐up using interactive voice response. The odds of response were over three‐quarters greater with postal follow‐up (OR 1.77; 95% CI 1.48 to 2.11) (Analysis 92.2). One trial (353 participants) evaluated the effect on response of administering the questionnaire by SMS compared to by Web. There was no evidence for an effect on response of administering the questionnaire by SMS (OR 0.68; 95% CI 0.31 to 1.49) (Analysis 93.2).
92.2. Analysis.
Comparison 92: Electronic with mail FU vs. electronic with interactive voice response FU, Outcome 2: Final response
93.2. Analysis.
Comparison 93: SMS vs. web, Outcome 2: Final Response
Contact ‐ Methods and number of requests for participation (Strategies 94‐121)
Postal
Fifty‐nine trials (89,146 participants) evaluated the effect on response of contacting participants before sending questionnaires. The odds of response were increased by a third when participants were pre‐notified (OR 1.36; 95% CI 1.23 to 1.51). There was considerable heterogeneity amongst the trial results (I2 = 87%) (Analysis 94.2). Seven trials (3322 participants) evaluated the effect on response of pre‐notification by telephone compared to by post. There was no evidence for an effect on response when participants were pre‐contacted by telephone instead of by post (OR 1.18; 95% CI 0.77 to 1.80). There was considerable heterogeneity amongst the trial results (I2 = 85%) (Analysis 95.2). Twenty‐four trials (53,555 participants) evaluated the effect on questionnaire response of follow‐up contact (e.g. repeat mailings or telephone calls) with participants who did not respond to the initial questionnaire. The odds of response increased by more than a quarter when follow‐up contact was used (OR 1.33; 95% CI 1.18 to 1.49). There was considerable heterogeneity amongst the results (I2 = 75%) and both Begg’s and Egger’s tests indicated evidence of selection bias (Analysis 96.2).
94.2. Analysis.
Comparison 94: Pre‐contact vs. no pre‐contact, Outcome 2: Final response
95.2. Analysis.
Comparison 95: Pre‐contact by phone vs. mail, Outcome 2: Final response
96.2. Analysis.
Comparison 96: Follow‐up vs. no follow‐up, Outcome 2: Final response
Thirteen trials (11,456 participants) evaluated the effect on response of providing participants with another copy of the questionnaire during postal follow‐up. The odds of response were increased by nearly a half when questionnaires were included during postal follow‐up (OR 1.41; 95% CI 1.13 to 1.77). There was considerable heterogeneity amongst these results (I2 = 82%) (Analysis 97.2). Eight trials (4057 participants) evaluated the effect on questionnaire response of using telephone rather than postal follow‐up. There was no evidence for an effect on response of using telephone follow‐up (OR 1.02; 95% CI 0.76 to1.38). There was moderate heterogeneity amongst the trial results (I2 = 66%) (Analysis 98.2).
97.2. Analysis.
Comparison 97: Postal follow‐up including vs. excluding q'aire, Outcome 2: Final response
98.2. Analysis.
Comparison 98: Follow‐up by phone vs. mail, Outcome 2: Final Response
Four trials (15,143 participants) evaluated the effect on response of a telephone reminder compared to no reminder. There was good evidence for an effect on response of using a telephone reminder (OR 1.96; 95% CI 1.03 to 3.74). There was considerable heterogeneity amongst the trial results (I2 = 90%) (Analysis 99.2). Six trials (7520 participants) evaluated the effect on questionnaire response of using a higher frequency follow‐up interval compared to a lower frequency follow‐up interval. The odds of response were increased by over one‐tenth using a higher frequency follow‐up interval (OR 1.13; 95% CI 1.02 to 1.25) (Analysis 100.2). One trial (780 participants) evaluated the effect on response of contacting participants by letter before sending questionnaires compared to pre‐contact by postcard. There was no evidence for an effect on response when participants were pre‐contacted by postcard instead of by letter (OR 0.98; 95% CI 0.74 to 1.30) (Analysis 101.2).
99.2. Analysis.
Comparison 99: Telephone reminder vs. no reminder, Outcome 2: Final response
100.2. Analysis.
Comparison 100: Higher frequency follow‐up interval vs. lower, Outcome 2: Final response
101.2. Analysis.
Comparison 101: Pre‐contact by letter vs. postcard, Outcome 2: Final Response
One trial (581 participants) evaluated the effect on response of contacting participants by letter before sending questionnaires compared to pre‐contact by email. There was no evidence for an effect on response when participants were pre‐contacted by letter instead of by email (OR 1.25; 95% CI 0.83 to 1.88) (Analysis 102.2). One trial (930 participants) evaluated the effect on response of contacting participants by fax before sending questionnaires compared to pre‐contact by post. There was no evidence for an effect on response when participants were pre‐contacted by fax instead of by post (OR 0.92; 95% CI 0.71 to 1.20) (Analysis 103.2). Two trials (582 participants) evaluated the effect on questionnaire response of follow‐up contact with participants by SMS or email, compared with no reminders. There was no evidence for an effect on response when electronic reminders were used (OR 1.80; 95% CI 0.88 to 3.68). There was moderate heterogeneity between the trial results (I2 = 34%) (Analysis 104.2).
102.2. Analysis.
Comparison 102: Pre‐contact letter vs email, Outcome 2: Final Response
103.2. Analysis.
Comparison 103: Pre‐contact by fax vs. mail, Outcome 2: Final response
104.2. Analysis.
Comparison 104: Electronic reminder vs. no reminder, Outcome 2: Final response
Two trials (3824 participants) evaluated the effect on response of push‐to‐web (i.e. initial requests sent by post and participants are asked to complete questionnaires over the Web) compared to mail‐push (initial mail contact with reminders of the paper questionnaire and an option to complete the survey online). There was no evidence for an effect on response with mail‐push (OR 1.10; 95% CI 0.87 to 1.39). There was moderate heterogeneity between the trial results (I2 = 60%) (Analysis 105.2). Four trials (3998 participants) evaluated the effect on response of sending a mixed‐mode reminder compared to a postal reminder. There was no evidence for an effect on response when non‐respondents were sent a mixed‐mode reminder (OR 1.13; 95% CI 0.83 to 1.52). There was moderate heterogeneity amongst the trial results (I2 = 52%) (Analysis 106.1).
105.2. Analysis.
Comparison 105: Push‐to‐web (web, web/paper reminder) vs. mail push (mail, mail/web reminder), Outcome 2: Final Response
106.1. Analysis.
Comparison 106: Postal vs mixed‐mode reminder (electronic/postal), Outcome 1: Final Response
Four trials (520 participants) evaluated the effect on response of a telephone reminder in addition to a postal reminder compared to a postal reminder only. The odds of response were increased by more than one‐half when a telephone reminder was included (OR 1.63; 95% CI 1.06 to 2.50). There was moderate heterogeneity amongst the trial results (I2 = 26%) (Analysis 107.2). Five trials (24,373 participants) evaluated the effect on response to a web survey of an email invitation compared to a postal invitation. There was no evidence for an effect on response when using a postal invitation (OR 1.81; 95% CI 0.81 to 4.01). There was considerable heterogeneity amongst the trial results (I2 = 98%) (Analysis 108.2). A single trial (431 participants) evaluated the effect on response of intensive follow‐up (i.e. questionnaires at 1, 6 and 12 months) compared with limited follow‐up (one questionnaire at 12 months). There was no evidence for an effect on response with intensive follow‐up (OR 1.69; 95% CI 0.93 to 3.06) (Analysis 109.1).
107.2. Analysis.
Comparison 107: Telephone reminder vs. standard reminder, Outcome 2: Final Response
108.2. Analysis.
Comparison 108: Email invitation to web survey vs. postal invitation, Outcome 2: Final Response
109.1. Analysis.
Comparison 109: Intensive follow‐up vs. limited, Outcome 1: Final response
Two trials (771 participants) evaluated the effect on response of a pre‐contact SMS (on the day of mailing) compared to a post‐notification SMS (a few days following mailing). There was no evidence for an effect on response when a post‐notification SMS was used (OR 1.29; 95% CI 0.66 to 2.54). There was moderate heterogeneity amongst the trial results (I2 = 56%) (Analysis 110.2). A single trial (5837 participants) evaluated the effect on response of sending a postal questionnaire with an electronic reminder compared to sending an e‐questionnaire with a postal reminder. There was no evidence of an effect on response when participants were sent an e‐questionnaire with a postal reminder (OR 1.05; 95% CI 0.95 to 1.16) (Analysis 111.2). A single trial (296 participants) evaluated the effect on response of giving study participants a calendar with prompts for when to return questionnaires. There was no evidence for an effect on response when participants were given a calendar with prompts (OR 1.00; 95% CI 0.57 to 1.73) (Analysis 112.2).
110.2. Analysis.
Comparison 110: Pre‐notification SMS vs. post‐notification SMS, Outcome 2: Final response
111.2. Analysis.
Comparison 111: Electronic with postal reminder vs. postal with electronic reminder, Outcome 2: Final Response
112.2. Analysis.
Comparison 112: Study calendar with prompts vs. no calendar, Outcome 2: Final Response
Electronic
Three trials (3,049 participants) evaluated the effect on e‐questionnaire response of contacting participants before sending questionnaires. The odds of response were almost doubled when participants were pre‐notified (OR 1.85; 95% CI 0.99 to 3.45). There was considerable heterogeneity amongst the trial results (I2 = 80%) (Analysis 94.4).
94.4. Analysis.
Comparison 94: Pre‐contact vs. no pre‐contact, Outcome 4: e ‐ Submission
Three trials (9947 participants) evaluated the effect of an SMS reminder compared to a postcard reminder. The odds of response increased by half when an SMS reminder was used (OR 1.49; 95% CI 1.23 to 1.81). There was moderate heterogeneity amongst the trial results (I2 = 61%) (Analysis 113.1). Three trials (7,159 participants) evaluated the effect on questionnaire response of follow‐up contact with participants by email compared with a mixed‐mode reminder (email and postal). The odds of response were doubled when a mixed‐mode reminder was used (OR 1.96; 95% CI 0.89 to 4.31). There was, however, considerable heterogeneity between the trial results (I2 = 94%) (Analysis 114.2).
113.1. Analysis.
Comparison 113: SMS vs. postcard reminder, Outcome 1: Final response
114.2. Analysis.
Comparison 114: Electronic vs. mixed‐mode reminder (email and postal), Outcome 2: Final Response
A single trial (734 participants) evaluated the effect on response of using a mixed‐mode first contact compared to electronic only. The odds of response were increased by half with a mixed‐mode first contact (OR 1.54; 95% CI 1.15 to 2.07) (Analysis 115.2).
115.2. Analysis.
Comparison 115: Electronic first vs. mixed‐mode first (mixed‐mode FU), Outcome 2: Final Response
One trial (500 participants) evaluated the effect on e‐questionnaire response of contacting participants by letter before sending e‐questionnaires compared to pre‐contact by postcard. There was no evidence for an effect on response when participants were pre‐contacted by postcard instead of by letter (OR 1.38; 95% CI 0.76 to 2.49) (Analysis 101.3). Four trials (26,482 participants) evaluated the effect on response of push‐to‐web (i.e. where initial requests are sent by post and participants are asked to complete questionnaires over the Web) compared to providing a choice of response modes (i.e. electronic or postal response). There was no evidence for an effect on response when providing a choice of response modes (electronic or postal response) compared to push‐to‐web (OR 1.09; 95% CI 0.99 to 1.20). There was moderate heterogeneity between the trial results (I2 = 34%) (Analysis 116.2).
101.3. Analysis.
Comparison 101: Pre‐contact by letter vs. postcard, Outcome 3: e‐Submission
116.2. Analysis.
Comparison 116: Push‐to‐web vs. choice, Outcome 2: Final Response
A single trial (3508 participants) evaluated the effect on response of push‐to‐web (i.e. where initial requests are sent by post and participants are asked to complete questionnaires over the Web) compared to mail only. The odds of response were increased by one‐quarter using mail only (OR 1.26; 95% CI 1.10 to 1.45) (Analysis 117.2). The same trial evaluated the effect on response of mail‐push (initial mail contact with reminders of the paper questionnaire and an option to complete the survey online) compared to mail only. There was no evidence for an effect on response when mail‐push was used (OR 0.96; 95% CI 0.84 to 1.10) (Analysis 118.2).
117.2. Analysis.
Comparison 117: Push‐to‐web (web, web/paper reminder) vs. mail only, Outcome 2: Final Response
118.2. Analysis.
Comparison 118: Mail push (mail, mail/web reminder) vs. mail only, Outcome 2: Final Response
A single trial (2982 participants) evaluated the effect on response of email augmentation of push‐to‐web (i.e. the addition of emailed versions of the advance letter and reminders, where participants are asked to complete questionnaires over the Web) compared with push‐to‐web without email augmentation. There was no evidence for an effect on response with email augmentation (OR 1.13; 95% CI 0.98 to 1.31) (Analysis 119.1).
119.1. Analysis.
Comparison 119: Push‐to‐web with email augmentation vs. no email augmentation, Outcome 1: Final response
A single trial (178 participants) evaluated the effect on response of sending an SMS reminder with a link to the e‐questionnaire compared to sending an SMS reminder without a link. There was no evidence for an effect on response when participants were sent an SMS reminder with a link (OR 1.00; 95% CI 0.55 to 1.82) (Analysis 120.2). A single trial (125 participants) evaluated the effect on response of sending an electronic prompt (email or SMS). There was no evidence for an effect on response when participants were sent an electronic prompt (OR 1.27; 95% CI 0.47 to 3.48) (Analysis 121.1).
120.2. Analysis.
Comparison 120: SMS reminder with URL vs. without, Outcome 2: Final Response
121.1. Analysis.
Comparison 121: Electronic prompt vs. none, Outcome 1: Final Response
Content ‐ Nature and style of questions (Strategies 122‐143)
Postal
Ten trials (21,393 participants) evaluated the effect on response of including a ’sensitive’ question in a questionnaire. The odds of response were reduced by nearly one‐tenth when sensitive questions were included (OR 0.94; 95% CI 0.88 to 1.00) (Analysis 122.2). A single trial (5817 participants) evaluated the effect on response of placing the more relevant questions at the start of the questionnaire. The odds of response were increased by a quarter when more relevant questions were placed first (OR 1.23; 95% CI 1.10 to 1.37) (Analysis 123.2). Three trials (11,435 participants) evaluated the effect on response of placing the most general questions at the start of the questionnaire. There was no evidence for an effect on response of placing general questions first (OR 0.95; 95% CI 0.83 to 1.09) (Analysis 124.1). Five trials (10,565 participants) evaluated the effect on questionnaire response of placing questions asking for demographic information first. There was no evidence for an effect on response of placing demographic items first (OR 1.02; 95% CI 0.90 to 1.16) (Analysis 125.2). Two trials (3182 participants) evaluated the effect on response of placing the easiest questions at the start of the questionnaire. The odds of response were increased by over a half when the easiest questions were presented first (OR 1.61; 95% CI 1.14 to 2.26) (Analysis 126.2). Two trials (4087 participants) evaluated the effect on response of using a more ’user‐friendly’ questionnaire. The odds of response were increased by almost half using user‐friendly questionnaires (OR 1.47; 95% CI 1.25 to 1.73) (Analysis 127.2). Four trials (6491 participants) evaluated the effect on response of using a more ’interesting’ or high salient questionnaire (e.g. asking questions particularly relevant to the study participants). The odds of response were nearly doubled using more interesting/salient questionnaires (OR 1.73; 95% CI 1.12 to 2.66). There was considerable heterogeneity between the trial results (I2 = 91%) (Analysis 128.2). Four trials (3092 participants) evaluated the effect on questionnaire response of using open‐ended rather than closed questions. The odds of response were reduced by more than half when open‐ended questions were used (OR 0.43; 95% CI 0.19 to 0.98). There was considerable heterogeneity between the trial results (I2 = 95%) (Analysis 129.2). One trial (300 participants) evaluated the effect of using open‐ended items first compared to other items first. There was no evidence for an effect on response of using open‐ended items first (OR 1.26; 95% CI 0.73 to 2.19) (Analysis 130.2). The same trial (300 participants) evaluated the effect of using closed‐ended items first compared to other items first. There was no evidence for an effect on response of using closed‐ended items first (OR 0.93; 95% CI 0.54 to 1.59) (Analysis 131.2). A single trial (1360 participants) evaluated the effect on response of including ’don’t know’ boxes for questions. There was no evidence for an effect on response of including ’don’t know’ boxes (OR 1.03; 95% CI 0.82 to 1.29) (Analysis 132.1). Two trials (1125 participants) evaluated the effect on response of using a “circle answer” rather than “tick box” format on question responses. There was no evidence for an effect on response of using a circle answer format (OR 0.96; 95% CI 0.74 to 1.26) (Analysis 133.1). A single trial (6783 participants) evaluated the effect of listing response options in increasing order on questionnaire response. There was no evidence for an effect on response of listing response options in increasing order (OR 1.06; 95% CI 0.94 to 1.18) (Analysis 134.1). Two trials (3882 participants) evaluated the effect on response of using high‐frequency response alternatives compared to medium‐frequency response alternatives. There was no evidence for an effect on response when high‐frequency response alternatives were used (OR 1.40; 95% CI 0.58 to 3.38). There was considerable heterogeneity between the trial results (I2 = 85%) (Analysis 135.1). Another trial (654 participants) evaluated the effect on questionnaire response of using a 5‐step response scale compared to a 10‐step response scale. There was no evidence for an effect on response of using a 5‐step response scale (OR 0.78; 95% CI 0.52 to 1.19) (Analysis 136.1). A single trial (1500 participants) evaluated the effect of using an individual‐item rather than a stem‐and‐leaf format on questionnaire response. There was no evidence for an effect on response of using an individual item format (OR 0.88; 95% CI 0.70 to 1.10) (Analysis 137.1). One trial (400 participants) evaluated the horizontal orientation of response options compared to vertical orientation of response options. The odds of response were three times greater when horizontal rather than vertical orientation was used (OR 3.12; 95% CI 1.63 to 5.96) (Analysis 138.1). Four trials (7345 participants) evaluated the effect on response of using a conventional mode of response technique compared to a randomised response technique. There was no evidence for an effect on response of using the conventional mode of response technique (OR 1.52; 95% CI 0.85 to 2.72) (Analysis 139.2). A single trial (1280 participants) evaluated the effect on response of asking ’factual’ questions only compared to factual and attitudinal questions. The odds of response were increased by more than a quarter using factual questions only (OR 1.34; 95% CI 1.01 to 1.77) (Analysis 140.1). One trial (200 participants) evaluated the effect on response of using a multi‐option consent form compared to a standard consent form. There was no evidence for an effect on response of using a multi‐option consent form (OR 0.91; 95% CI 0.49 to 1.68) (Analysis 141.1). One trial (259 participants) evaluated the effect on response of questions ordered by time period compared to those not ordered by time period. There was no evidence for an effect on response of using questionnaires where questions are ordered by time period (OR 1.48; 95% CI 0.84 to 2.59) (Analysis 142.1). Two trials (226 participants) evaluated the effect on response of placing clinical outcome questions first compared to placing them last. The odds of response were doubled when clinical outcome questions were last (OR 2.05; 95% CI 0.99 to 4.25) (Analysis 143.2).
122.2. Analysis.
Comparison 122: Sensitive questions vs. no/fewer/less sensitive questions asked, Outcome 2: Final response
123.2. Analysis.
Comparison 123: More relevant questions first vs. last, Outcome 2: Final response
124.1. Analysis.
Comparison 124: Most general questions first vs. last, Outcome 1: Final response
125.2. Analysis.
Comparison 125: Demographic items first vs. last, Outcome 2: Final response
126.2. Analysis.
Comparison 126: Easier questions first vs. last, Outcome 2: Final response
127.2. Analysis.
Comparison 127: User friendly vs. standard questionnaire, Outcome 2: Final response
128.2. Analysis.
Comparison 128: More interesting vs. less or high salient topic vs. low, Outcome 2: Final response
129.2. Analysis.
Comparison 129: Open‐ended vs. closed questions, Outcome 2: Final response
130.2. Analysis.
Comparison 130: Open‐ended items first vs. other items first, Outcome 2: Final response
131.2. Analysis.
Comparison 131: Closed‐ended items first vs. other items first, Outcome 2: Final response
132.1. Analysis.
Comparison 132: 'Don't know' boxes included vs. not, Outcome 1: Final response
133.1. Analysis.
Comparison 133: Circle answer vs. tick box format, Outcome 1: Final response
134.1. Analysis.
Comparison 134: Response options listed in increasing vs. decreasing order, Outcome 1: Final response
135.1. Analysis.
Comparison 135: High vs. medium frequency response alternatives, Outcome 1: Final response
136.1. Analysis.
Comparison 136: 5‐step vs. 10‐step response scale, Outcome 1: Final response
137.1. Analysis.
Comparison 137: Individual item vs. stem & leaf format, Outcome 1: Final response
138.1. Analysis.
Comparison 138: Horizontal vs. vertical orientation of response options, Outcome 1: Final response
139.2. Analysis.
Comparison 139: Conventional vs. randomised response technique, Outcome 2: Final response
140.1. Analysis.
Comparison 140: Factual questions only vs. factual and attitudinal questions, Outcome 1: Final response
141.1. Analysis.
Comparison 141: Multi‐option vs. standard consent form, Outcome 1: Final response
142.1. Analysis.
Comparison 142: Questions ordered by time period vs. other order, Outcome 1: Final response
143.2. Analysis.
Comparison 143: Clinical outcome questions first vs. last, Outcome 2: Final Response
Electronic
One trial (2176 participants) evaluated the effect on response of using a more 'interesting' e‐questionnaire (e.g. asking questions particularly relevant to the study participants). The odds of response were almost doubled using a more interesting e‐questionnaire (OR 1.85; 95% CI 1.52 to 2.26) (Analysis 128.3).
128.3. Analysis.
Comparison 128: More interesting vs. less or high salient topic vs. low, Outcome 3: e ‐ Submission
Origin ‐ Who sent the questionnaire? (Strategies 144‐150)
Postal
Fourteen trials (21,628 participants) evaluated the effect on response of university sponsorship. The odds of response were increased by more than a quarter when questionnaires originated from a university rather than an alternative source, such as a government department or commercial organisation (OR 1.32; 95% CI 1.13 to 1.54). There was considerable heterogeneity between trial results (I2 = 83%) (Analysis 144.2). Eleven trials (5686 participants) evaluated the effect on response when questionnaires were sent or signed by a more senior or well‐known person. There was no evidence for an effect on response when a more senior or well‐known person sent or signed the questionnaire (OR 1.05; 95% CI 0.90 to 1.23). There was moderate heterogeneity between the trial results (I2 = 41%) (Analysis 147.2).
144.2. Analysis.
Comparison 144: University sponsor/source vs. other, Outcome 2: Final response
147.2. Analysis.
Comparison 147: Sent or signed by more vs. less senior/well‐known person, Outcome 2: Final response
A single trial (500 participants) evaluated the effect on questionnaire response of sending the questionnaire in a university‐printed envelope. There was no evidence for an effect on response of sending the questionnaire in a university‐printed envelope (OR 0.88; 95% CI 0.61 to 1.28) (Analysis 146.2). Two trials (924 participants) evaluated the effect on response of pre‐contact by a medical researcher compared to a nonmedical researcher. There was no evidence for an effect on response of pre‐contact by a medical researcher (OR 1.01; 95% CI 0.55 to 1.86). There was considerable heterogeneity between the trial results (I2 = 72%) (Analysis 148.1). Two trials (1106 participants) evaluated the effect on response when questionnaires were sent from a GP rather than a research group. There was no evidence for an effect on response of sending questionnaires by a GP (OR 1.52; 95% CI 0.73 to 3.15). There was considerable heterogeneity between the trial results (I2 = 84%) (Analysis 149.2). Five trials (5959 participants) evaluated the effect on response of whether the ethnicity of the name of the person sending the questionnaire was identifiable. There was no evidence for an effect on response when names were ethnically identifiable (OR 1.07; 95% CI 0.90 to 1.27) (Analysis 180.2). Two trials (3146 participants) evaluated the effect of sending the questionnaire from a male investigator compared to a female investigator. There was no evidence for an effect on response of sending the questionnaire from a male investigator (OR 1.07; 95% CI 0.72 to 1.58) (Analysis 150.2).
146.2. Analysis.
Comparison 146: University printed envelope vs. plain, Outcome 2: Final response
148.1. Analysis.
Comparison 148: Pre‐contact by medical researcher vs. non medical researcher, Outcome 1: Final response
149.2. Analysis.
Comparison 149: Q'aire sent by GP vs. by research group, Outcome 2: Final response
180.2. Analysis.
Comparison 180: Ethnically unidentifiable/white vs. other name, Outcome 2: Final response
150.2. Analysis.
Comparison 150: Male vs. female investigator or male vs. female signature, Outcome 2: Final response
Electronic
Two trials (3845 participants) evaluated the effect on e‐questionnaire response of university sponsorship. There was no evidence for an effect on e‐questionnaire response by using university sponsorship (OR 0.84; 95% CI 0.69 to 1.01) (Analysis 144.4). Two trials (658 participants) evaluated the effect on e‐questionnaire response of ‘higher’ university sponsorship (i.e. university logo featured prominently on every page of the surveys) compared with ‘lower’ university sponsorship (i.e. university logo did not appear anywhere on the surveys, although its name was mentioned in the information sheets). There was no evidence for an effect on response of using ‘higher’ university sponsorship (OR 0.96; 95% CI 0.63 to 1.45) (Analysis 145.1).
144.4. Analysis.
Comparison 144: University sponsor/source vs. other, Outcome 4: e ‐ Submission
145.1. Analysis.
Comparison 145: Higher university sponsorship vs. lower, Outcome 1: e ‐ Submission
Two trials (720 participants) evaluated the effect of sending the e‐questionnaire from a male compared to a female investigator. The odds of response decreased by over a half when the e‐questionnaire was from a male investigator (OR 0.55; 95% CI 0.38 to 0.80) (Analysis 150.3). Six trials (28,162 participants) evaluated the effect on response when e‐questionnaires were sent or signed by a more senior or well‐known person. There was no evidence for an effect on response when a more senior or well‐known person sent or signed the e‐questionnaire (OR 1.09; 95% CI 0.96 to 1.25). There was moderate heterogeneity amongst the trial results (I2 = 41%; I2 = 69%) (Analysis 147.4).
150.3. Analysis.
Comparison 150: Male vs. female investigator or male vs. female signature, Outcome 3: e ‐ Submission
147.4. Analysis.
Comparison 147: Sent or signed by more vs. less senior/well‐known person, Outcome 4: e ‐ Submission
Communication ‐ What are participants told? (Strategies 151‐178)
Postal
One trial (25,000 participants) evaluated the effect on questionnaire response of providing participants with an assurance of confidentiality. The odds of response were increased by more than a quarter with an assurance of confidentiality (OR 1.33; 95% CI 1.24 to 1.42) (Analysis 151.1). One trial (468 participants) evaluated the effect on questionnaire response of including a statement that others had responded to. There was no evidence for an effect on response when the statement was included (OR 1.12; 95% CI 0.76 to 1.65) (Analysis 152.2). Five trials (5544 participants) evaluated the effect on questionnaire response of offering participants the choice to opt out of the study. There was no evidence for an effect on response when participants could opt out (OR 0.96; 95% CI 0.74 to 1.25). There was considerable heterogeneity between the trial results (I2 = 80%) (Analysis 153.2).
151.1. Analysis.
Comparison 151: Assurance of confidentiality vs. none, Outcome 1: Final response
152.2. Analysis.
Comparison 152: Included statement that others had responded vs. no statement, Outcome 2: Final response
153.2. Analysis.
Comparison 153: Choice to opt‐out from study vs. none, Outcome 2: Final response
A single trial (2000 participants) evaluated the effect on response of providing instructions for completion of the questionnaire. There was no evidence for an effect on response when instructions were given (OR 0.89; 95% CI 0.74 to 1.06) (Analysis 154.1). Six trials (5661 participants) evaluated the effect on response of giving participants a deadline by which to respond. There was no evidence for an effect on response of giving a deadline (OR 1.00; 95% CI 0.84 to 1.19). There was moderate heterogeneity between the trial results (I2 = 48%) (Analysis 155.2). Three trials (600 participants) evaluated the effect on response of mention of an obligation to respond compared to no mention of an obligation to respond. The odds of response increased by more than half with the mention of an obligation to respond (OR 1.61; 95% CI 1.16 to 2.22) (Analysis 156.2).
154.1. Analysis.
Comparison 154: Instructions given vs. not, Outcome 1: Final response
155.2. Analysis.
Comparison 155: Response deadline given vs. no deadline, Outcome 2: Final response
156.2. Analysis.
Comparison 156: Mention of obligation to respond vs. none, Outcome 2: Final response
One trial (702 participants) evaluated the effect on response of questionnaires including a request for a telephone number. There was no evidence for an effect on response of requesting a telephone number (OR 1.00; 95% CI 0.65 to 1.54) (Analysis 157.2). One trial (200 participants) evaluated the effect of asking participants to respond on the questionnaire itself compared to asking them to respond on a separate form. There was no evidence for an effect on response of asking the participants to respond on the questionnaire rather than on a separate form (OR 1.13; 95% CI 0.57 to 2.27) (Analysis 158.2).
157.2. Analysis.
Comparison 157: Request for telephone number vs. none, Outcome 2: Final response
158.2. Analysis.
Comparison 158: Respond on questionnaire vs. on separate form, Outcome 2: Final response
Seven trials (7053 participants) evaluated the effect on questionnaire response of telling participants that they would be contacted again if they did not respond. There was no evidence for an effect on response if mention of follow‐up was used (OR 1.02; 95% CI 0.91 to 1.15) (Analysis 159.2). Two trials (1907 participants) evaluated the effect on questionnaire response of requesting an explanation for non‐participation. There was no evidence for an effect on response of requesting an explanation for non‐participation (OR 1.14; 95% CI 0.83 to 1.57). There was moderate heterogeneity amongst the trial results (I2 = 62%) (Analysis 160.2). One trial (600 participants) evaluated the effect on response of providing a time estimate for completion of the questionnaire. There was no evidence for an effect on response when a time estimation was provided (OR 1.10; 95% CI 0.76 to 1.58) (Analysis 161.2).
159.2. Analysis.
Comparison 159: Mention of follow‐up contact vs. none, Outcome 2: Final response
160.2. Analysis.
Comparison 160: Explanation for non‐participation requested vs. not, Outcome 2: Final response
161.2. Analysis.
Comparison 161: Time estimate for completion given vs. not, Outcome 2: Final response
One trial (500 participants) evaluated the effect on response of a detailed cover letter compared to a brief cover letter. There was no evidence for an effect on response by using the detailed cover letter (OR 1.08; 95% CI 0.74 to 1.58) (Analysis 162.2). Two trials (1251 participants) evaluated the effect on response of the presence of an appeal or a pleading factor in the cover letter. There was no evidence for an effect on response of using an appeal (OR 1.06; 95% CI 0.79 to 1.42) (Analysis 163.1). One trial (100 participants) evaluated the effect of a note requesting participants not to remove an ID Code. The odds of response decreased by more than a half when the note was added (OR 0.37; 95% CI 0.14 to 0.96) (Analysis 164.2).
162.2. Analysis.
Comparison 162: Detailed vs. brief cover letter, Outcome 2: Final response
163.1. Analysis.
Comparison 163: Appeal vs. none, Outcome 1: Final response
164.2. Analysis.
Comparison 164: Note requesting not to remove ID code vs. none, Outcome 2: Final response
A single trial (201 participants) evaluated the effect on response of a request for the participant’s signature. There was no evidence of an effect on response when participants’ signatures were requested (OR 1.19; 95% CI 0.65 to 2.18) (Analysis 165.1). Another trial (395 participants) evaluated the effect of endorsing the questionnaire by eminent professionals in the field. The odds of response decreased by more than a quarter when an endorsement was used (OR 0.63; 95% CI 0.43 to 0.94) (Analysis 166.2). One trial (671 participants) evaluated the effect of a veiled threat in follow‐up letters. The odds of response doubled when a veiled threat was used (OR 2.09; 95% CI 1.49 to 2.93) (Analysis 167.2). Eight trials (10,908 participants) evaluated the effect on questionnaire response of stressing how response would benefit the sponsor. There was no evidence for an effect on response when stressing the benefits to the sponsor (OR 0.99; 95% CI 0.86 to 1.13). There was moderate heterogeneity amongst the trial results (I2 = 56%) and both Begg’s and Egger’s tests indicated evidence of selection bias (Analysis 168.2). Ten trials (15,159 participants) evaluated the effect on questionnaire response of stressing how response would benefit the participant. There was no evidence for an effect on response when stressing the benefits to participants (OR 1.00; 95% CI 0.85 to 1.17). There was considerable heterogeneity amongst the trial results (I2 = 78%) (Analysis 169.2).
165.1. Analysis.
Comparison 165: Request for participant signature vs. none, Outcome 1: Final response
166.2. Analysis.
Comparison 166: Questionnaire endorsed vs. not endorsed, Outcome 2: Final response
167.2. Analysis.
Comparison 167: Veiled threat in follow‐up letter vs. none, Outcome 2: Final response
168.2. Analysis.
Comparison 168: Appeal stresses benefit to sponsor vs. other, Outcome 2: Final response
169.2. Analysis.
Comparison 169: Appeal stresses benefit to respondent vs. other, Outcome 2: Final response
Fourteen trials (36,107 participants) evaluated the effect on questionnaire response of stressing how response would benefit society. There was no evidence for an effect on response of stressing the benefits to society (OR 1.07; 95% CI 0.95 to 1.20). There was considerable heterogeneity between trial results (I2 = 72%) and both Begg’s and Egger’s tests indicated evidence of selection bias (Analysis 170.2). Two trials (2070 participants) evaluated the effect on response of questionnaires remaining anonymous compared with being identifiable. There was no evidence for an effect on response of questionnaires remaining anonymous (OR 0.96; 95% CI 0.66 to 1.39). There was considerable heterogeneity between the trial results (I2 = 72%) (Analysis 171.1).
170.2. Analysis.
Comparison 170: Appeal stresses benefit to society vs. other, Outcome 2: Final response
171.1. Analysis.
Comparison 171: Anonymous vs. not anonymous, Outcome 1: Final response
Two trials (27,119 participants) evaluated the effect on response of using a cover letter that highlighted salience. There was no evidence for an effect on response of a letter that highlighted salience (OR 1.06; 95% CI 0.75 to 1.50). There was considerable heterogeneity between the trial results (I2 = 75%) (Analysis 172.2). A single trial (2180 participants) evaluated the effect on response by using a cover letter that highlighted salience in the first mailing compared with using one during follow‐up. The odds of response when using a cover letter that highlights salience in the first mailing were over twice the odds of response when one was used during follow‐up (OR 2.49; 95% CI 1.82 to 3.40) (Analysis 173.3).
172.2. Analysis.
Comparison 172: Cover letter highlights salience vs. standard cover letter, Outcome 2: Final response
173.3. Analysis.
Comparison 173: Salient cover letter message on 1st mailing vs. follow‐up, Outcome 3: Final response
One trial (4447 participants) evaluated the effect on questionnaire response of informing participants that their responses were being monitored. The odds of response were increased by more than a tenth when the letter stated that responses were being monitored (OR 1.15; 95% CI 1.01 to 1.31) (Analysis 174.2). A single trial (1418 participants) evaluated the effect on response of using a cover letter that emphasised harm prevention compared with one that emphasised health promotion. There was no evidence of an effect on response when the letter emphasised harm prevention (OR 1.19; 95% CI 0.83 to 1.72) (Analysis 175.2). The same trial evaluated the effect on response of using a cover letter that emphasised harm prevention compared with one that contained a neutral message. The odds of response were increased by more than two‐fifths when the letter emphasised harm prevention (OR 1.44; 95% CI 0.98 to 2.12) (Analysis 176.2).
174.2. Analysis.
Comparison 174: Letter states responses being monitored vs. standard letter, Outcome 2: Final response
175.2. Analysis.
Comparison 175: Letter emphasises health promotion vs. harm prevention, Outcome 2: Final response
176.2. Analysis.
Comparison 176: Letter emphasises harm prevention vs. neutral message, Outcome 2: Final response
One trial (1192 participants) evaluated the effect on questionnaire response by sending a letter with behaviour change techniques in the text. The odds of response were increased by more than a quarter using the letter with behaviour change techniques in the text (OR 1.39; 95% CI 1.08 to 1.77) (Analysis 177.1). A single trial (1316 participants) evaluated the effect on response of using a culturally sensitive cover letter. There was no evidence for an effect on response using a culturally sensitive cover letter (OR 1.00; 95% CI 0.74 to 1.34) (Analysis 179.1).
177.1. Analysis.
Comparison 177: Behaviour change letter vs. standard, Outcome 1: First response
179.1. Analysis.
Comparison 179: Culturally sensitive letter vs. generic, Outcome 1: Final response
Electronic
Three trials (23,777 participants) evaluated the effect on e‐questionnaire response by including a statement that others had responded to. There was no evidence for an effect on response when the statement was included (OR 1.14; 95% CI 0.83 to 1.56). There was considerable heterogeneity between the trial results (I2 = 94%) (Analysis 152.4).
152.4. Analysis.
Comparison 152: Included statement that others had responded vs. no statement, Outcome 4: e ‐ Submission
A single trial (8586 participants) evaluated the effect on e‐questionnaire response of giving participants a deadline by which to respond. The odds of response increased by over a tenth when given a deadline (OR 1.18; 95% CI 1.03 to 1.34) (Analysis 155.4). Three trials (3536 participants) evaluated the effect on e‐questionnaire response by stressing how responses would benefit society. There was no evidence for an effect on response when stressing the benefits to society (OR 1.35; 95% CI 0.95 to 1.91). There was moderate heterogeneity between trial results (I2 = 41%) (Analysis 170.3). Four trials (5915 participants) evaluated the effect of including an appeal, such as “request for help” in the subject line of the email. There was no evidence of an effect on response by including an appeal in the subject line (OR 1.07; 95% CI 0.79 to 1.47). There was considerable heterogeneity between the trial results (I2 = 71%) (Analysis 163.3).
155.4. Analysis.
Comparison 155: Response deadline given vs. no deadline, Outcome 4: e ‐ Submission
170.3. Analysis.
Comparison 170: Appeal stresses benefit to society vs. other, Outcome 3: e‐Submission
163.3. Analysis.
Comparison 163: Appeal vs. none, Outcome 3: e ‐ Submission
A single trial (1250 participants) evaluated the effect on e‐questionnaire response of a detailed letter compared to a brief letter. The odds of response were over three times greater when using the brief letter (OR 3.26; 95% CI 1.79 to 5.94) (Analysis 162.3). One trial (2358 participants) evaluated the effect on response of telling participants that the e‐questionnaire would take 10 minutes to complete compared with telling them that it would take 30 minutes. There was no evidence for an effect on response by giving a longer time estimate (OR 1.25; 95% CI 0.96 to 1.64) (Analysis 178.2).
162.3. Analysis.
Comparison 162: Detailed vs. brief cover letter, Outcome 3: e‐Submission
178.2. Analysis.
Comparison 178: Participants told completion time 10 mins vs. 30 mins, Outcome 2: e ‐ Submission
Length ‐ How long is the questionnaire? (Strategies 183‐87)
Postal
Seventy‐two trials (84,954 participants), including two unpublished trials, evaluated the effect of questionnaire length on response. The odds of response increased by more than half using shorter questionnaires (OR 1.58; 95% CI 1.40 to 1.78). Heterogeneity amongst trial results was apparent on inspection of the forest plot, and in the Chi2 test result (P < 0.00001) and I2 result (93%) (Analysis 183.2). One trial (600 participants) evaluated the effect on questionnaire response of using a double postcard compared to one page. The odds of response decreased by half when a double postcard was used (OR 0.47; 95% CI 0.34 to 0.66) (Analysis 184.2). A single trial (1795 participants) evaluated the effect of sending the questionnaire with a supplement compared to sending the questionnaire alone. There was no evidence for an effect on response of sending a questionnaire with a supplement (OR 0.86; 95% CI 0.70 to 1.07) (Analysis 185.1). Two trials (4943 participants) evaluated the effect on response of including a questionnaire for relatives. The odds of response were reduced by one‐third when a questionnaire for relatives was included (OR 0.67; 95% CI 0.60 to 0.76) (Analysis 186.1). One trial (414 participants) evaluated the effect of including a consent form with the questionnaire. There was no evidence for an effect on response of including a consent form (OR 1.32; 95% CI 0.89 to 1.95) (Analysis 187.2).
183.2. Analysis.
Comparison 183: Shorter vs. longer questionnaire, Outcome 2: Final response
184.2. Analysis.
Comparison 184: Double postcard vs. one page, Outcome 2: Final response
185.1. Analysis.
Comparison 185: Questionnaire sent with supplement vs. alone, Outcome 1: Final response
186.1. Analysis.
Comparison 186: Extra questionnaire for relatives included vs. not, Outcome 1: Final response
187.2. Analysis.
Comparison 187: Consent form included vs. not, Outcome 2: Final response
Electronic
Five trials (12,325 participants) evaluated the effect of the length of electronic questionnaires on response. The odds of response increased by half when using shorter e‐questionnaires (OR 1.51; 95% CI 1.06 to 2.16). There was considerable heterogeneity amongst the trial results (I2 = 94%) (Analysis 183.4).
183.4. Analysis.
Comparison 183: Shorter vs. longer questionnaire, Outcome 4: e ‐ Submission
Discussion
Summary of main results
This updated review identified a total of 758 eligible studies that evaluated 187 strategies to increase response to postal and electronic questionnaires, adding 245 new trials to the 513 studies included in the previously published version (Edwards 2009). We found substantial heterogeneity amongst trial results in half of the strategies.
The findings relevant to increasing questionnaire response include: contacting people before they are sent the questionnaire, sending postal questionnaires by first‐class post or by a special (recorded) delivery service, and providing a stamped‐return envelope. Questionnaires, letters, and emails can be made more personal, and kept short; incentives can be offered with a postal questionnaire, for example, a small amount of money, or a non‐monetary incentive such as a pen; one or more reminders can be sent with a copy of the questionnaire to people who do not reply; response to postal questionnaires can also be increased if they originate from a university. Using postal rather than electronic questionnaires or providing people with a choice of response modes (electronic or postal) can increase response. Response to an electronic questionnaire can be increased if it is administered over a computer rather than a smartphone. Monetary and non‐monetary incentives can also help to increase response to electronic questionnaires.
We have chosen to use odds ratios in our analyses for methodological reasons. However, the practical implication of the odds ratio for a strategy is difficult to interpret without knowing the baseline response rate (without the strategy). Moreover, the odds ratio for a strategy might vary in relationship to the baseline response rate. Therefore, those conducting postal and electronic surveys should scrutinise the data in the relevant results tables closely if the magnitude of the effect that they might expect from using a specific strategy is an important consideration for them in deciding whether to use the strategy. A table showing the conversion of odds ratios to response proportions for a range of different baselines is included in Appendix 2.
Summary of evidence since last published version
Many of the 245 new trials added to this review update evaluated previously identified strategies (e.g. incentives, length, and personalisation). Many of the effect estimates of strategies to increase questionnaire response presented in this update are similar to those reported in the last published version of the review (Edwards 2009) but are now more precise (i.e. confidence intervals are narrower now than before). In a few cases, the addition of new trials changed our conclusions: for example, there is now some evidence for an effect on postal questionnaire response by using a larger non‐monetary incentive; also, there is now evidence that monetary incentives increase electronic questionnaire response. Strategies that emerged in this update that were not reported previously are: using postal rather than electronic questionnaires and providing people with a choice of response modes (electronic or postal) can increase response.
Overall completeness and applicability of evidence
We found 670 eligible trials with postal questionnaires that evaluated over 100 different ways of increasing response and 88 eligible trials with electronic questionnaires that evaluated over 30 different ways of increasing response. The types of participants in these trials include a wide range of people likely to be asked to complete a questionnaire, from clinical trial participants, patients and healthcare providers, university students and faculty, to marketing managers, industrial accountants, microwave oven owners, and grocery store managers. All trials reported the required outcomes: the proportions of participants responding to the first or final mailings of a postal questionnaire, and the proportions of participants logging‐in, clicking a hyperlink, or submitting an online questionnaire.
Inadequate allocation concealment can bias the results of clinical trials (Schulz 1995). In our review, information on allocation concealment was unavailable for most of the included trials. If they were inadequately concealed, this may have biased the results. Blinding of outcome assessors reduces detection bias (Higgins 2022). However, in the eligible trials in our review update, no outcomes were assessed because we were only interested in the counts of responses in the experimental and control groups, and so there was little or no risk of detection bias in this review.
Quality of the evidence
As all the included studies were randomised trials, the overall quality of the body of evidence presented in this review is ‘high’. However, we found considerable statistical heterogeneity amongst trial results in half of the strategies, and for these, the pooled odds ratios may not be meaningful. Variation between trial interventions and populations is likely to explain some of the heterogeneity. For example, amongst trials evaluating non‐monetary incentives, the types of incentives used are considerably heterogeneous, including things such as donations to charity, lottery participation, and a free key‐ring or pen. Amongst trials evaluating monetary incentives, the amounts of money offered to participants varied between trials. A meta‐regression analysis has shown that monetary incentives can increase response to postal questionnaires but that the relationship between the amount of money and response is not linear (Edwards 2005). Amongst the trials evaluating shorter and longer questionnaires, the length of the questionnaires used varied between trials, some comparing a single page with a two‐page alternative, and others comparing four or more pages with longer alternatives. In a meta‐regression analysis, most of the heterogeneity in trial results was explained by variation in the length of the questionnaires used in each trial (Edwards 2004). A subgroup analysis of the trials of personalisation in postal questionnaires found that response was increased by addressing participants by name on cover letters, and that the effect appeared to be enhanced by including a handwritten signature (Scott 2006). Due to the remaining unexplained heterogeneity in other strategies, we downgraded the overall quality rating of the body of evidence presented in this review to ‘moderate’.
Potential biases in the review process
The identification and inclusion of all relevant trials in systematic reviews reduces random error in meta‐analyses and, because ease of identification of trials is associated with intervention effects, complete ascertainment may also reduce bias (Clarke 1994). We excluded some trials because we could not confirm that participants had been randomly allocated to intervention and control groups, and we have not examined whether the results of these trials differed systematically from the included trials. Although tests for selection bias were significant in fifteen strategies, these results may be due to true heterogeneity between trial results, rather than bias in the selection of trials (Egger 1997).
Agreements and disagreements with other studies or reviews
Two other systematic reviews and one meta‐analysis of methods to increase questionnaire response have appeared in the survey research literature during the 30 years prior to this review.
The largest of these (Yammarino 1991) included 115 studies published between 1940 and 1988. It also found evidence that: repeated contacts (preliminary notification and follow‐up), appeals in letters, inclusion of a return envelope, types of postage, monetary incentives (particularly $0.50 or less), and shorter questionnaires increased response. However, it did not find evidence that either sponsorship or non‐monetary incentives increased response. It is unclear in this meta‐analysis whether only RCTs were included, which, in addition to the smaller number of included studies, may explain why its findings differ from those of our review.
The next largest (Price 2022) included 40 randomised trials of patient experience surveys only, conducted in the US. It presented a descriptive account of the included studies with no meta‐analysis. As in our review, it concluded the following: that pre‐notification, special delivery, and monetary incentives (particularly unconditional ones) increased response; it also found evidence that questionnaires administered using web‐based modes only resulted in lower response rates than those administered by mail. Unlike our review, however, it was uncertain about any effects of questionnaire length on response.
The third (Nakash 2006) included 13 randomised trials of healthcare studies on only patient populations. As in our review, it found evidence that follow‐up (particularly more intense follow‐up), and shorter questionnaires increased response. Unlike our review, however, it found no evidence for any effects of incentives on response. The reason for this different result may be that it only included four trials of non‐monetary incentives. Our review includes 146 trials of non‐monetary incentives and shows that the odds of response can be increased by over a tenth when a non‐monetary incentive is used.
The most likely reason for differences in the findings of our review with those of the reviews described above is the huge difference in the number of studies included.
Authors' conclusions
Implication for systematic reviews and evaluations of healthcare.
Researchers can increase response to postal and electronic questionnaires by using the strategies shown to be effective in this systematic review. Some strategies will require additional materials or administrative time whereas others can be implemented at little or no extra cost. For example, researchers may be able to double the odds of response by offering participants payment for completion of questionnaires or by using recorded delivery, both of which will add substantially to costs for large studies. The use of non‐monetary incentives, on the other hand, may be more affordable, but is likely to be less effective in encouraging response.
Implication for methodological research.
Further analyses (for example, using random‐effects meta‐regressions) may reveal important sources of variation, for example, due to methodological quality, questionnaire topic, the years in which each study was done, or types of population. In this review, our aim was to systematically identify and critically appraise eligible trials, and to present the relevant data. We did not intend to produce single effect estimates for every strategy. For many strategies, although there was statistical heterogeneity, the directions of the effects were similar. For these strategies, we cannot be sure about the size of the effect, but we can be reasonably confident that there was an effect on response.
The results of this review show that questionnaire length has a substantial impact on non‐response, particularly when questionnaires are very short. In the context of outcome data collection in a clinical trial, the use of a short questionnaire would be expected to minimise non‐response, thus increasing the effective sample size and reducing sampling error. However, if the use of short questionnaires reduces the accuracy of the measurement process, the reduction in random error achieved by increased follow‐up would have to be traded‐off against increased random error due to using less precise measurements. Further research is underway by the authors to quantify this trade‐off, so that outcome measures can be designed for use in clinical trials that minimise total random error (sampling error and measurement error).
This review examined the effectiveness of 187 different strategies to increase the response to postal and electronic questionnaires. The outcome of interest in this review was the overall response proportion, and we did not examine the impact of factors that may influence the completeness of the returned questionnaires. However, factors that influence the readability of questionnaires, such as the number of syllables per word, words per sentence, typeface and font size may have an important effect on both the proportion of questions that are answered and indeed the overall response proportion.
One‐third of clinical trials, case‐control and cohort studies collect data from participants using a questionnaire, and more than a quarter collect data using interviews with participants (Van Gelder 2010). If those who are eligible for a study or those who agree to take part do not respond to these questionnaires or refuse to take part in interviews, this will reduce study power and may introduce bias in the results that makes them misleading and useless. Good evidence exists in this review for some methods that might be used to increase response to self‐completed questionnaires, and this evidence has been used to achieve over 90% data completion in some biomedical research studies (Butler 2013; Edwards 2005b; Free 2011). However, less is known about effective methods to increase participation in interviews, and we plan to conduct a Cochrane Methodology Review to address this gap in the evidence.
What's new
| Date | Event | Description |
|---|---|---|
| 22 December 2021 | New search has been performed | Third update of the review (new search December 2021). |
| 22 December 2021 | New citation required but conclusions have not changed | This is the third update of the review (new search December 2021). The current update now includes 670 eligible trials that evaluated over 100 different strategies for increasing response to postal questionnaires as well as 88 eligible trials that evaluated over 30 different strategies for increasing response to electronic questionnaires. There has been a change in authorship, with two new authors having been added and five previous authors agreeing to be acknowledged in this updated version. An important methodological finding in this update is that the response rate is increased using postal rather than electronic questionnaires (Analysis 81.1; Analysis 81.2). |
History
Protocol first published: Issue 2, 1999 Review first published: Issue 3, 2001
| Date | Event | Description |
|---|---|---|
| 12 May 2009 | New citation required but conclusions have not changed | The current update includes randomised controlled trials of questionnaires distributed by electronic mail, and strategies designed to improve response to online or web surveys. |
| 10 December 2008 | New search has been performed | This review has been updated (new search December 2007). The current update includes 481 eligible trials that evaluated 110 different strategies for increasing response to postal questionnaires and 32 eligible trials that evaluated 27 different strategies for increasing response to electronic questionnaires. A new search was re‐run February 2009 in MEDLINE and Psychinfo and 23 possibly eligible trials are listed under Studies awaiting classification. |
| 27 December 2007 | Amended | Converted to new review format. |
Acknowledgements
This Cochrane review was originally supported by a grant from the BUPA Foundation and by a Nuffield Trust Short Term Fellowship and was initially conducted with support from Cochrane Injuries (closed in March 2023). The initial motivation for the review came from the need to find ways to ensure high rates of follow‐up in the MRC CRASH‐1 Trial.
Sir Iain Chalmers, Professor Peter Sandercock, Professor Catherine Peckham, and the MRC CRASH‐1 Trial Management Group were acknowledged for their help and advice with the first version of the review (see Edwards 2009). The 2008 update to this review was supported by a second grant from the BUPA Foundation (see Edwards 2009). We also wish to acknowledge the help of Reinhard Wentz, Sarah Pratap, Irene Kwan, Rachel Cooper, and Lambert Felix, who all assisted in previous versions of the review. This review update was funded by the National Institute for Health and Care Research (NIHR) Evidence Synthesis Programme (NIHR133238) Programme Grant Scheme. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.
Editorial and peer‐review contributions
Cochrane Methodology supported the authors in the development of this review update. The following people conducted the editorial process for this review update:
Sign‐off Editor (final editorial decision): Tari Turner, Cochrane Australia;
Managing Editor (provided editorial guidance to authors, edited the article): Joey Kwong, Cochrane Central Editorial Service;
Editorial Assistant (conducted editorial policy checks, selected peer reviewers, collated peer‐reviewer comments, supported editorial team): Sara Hales‐Brittain, Cochrane Central Editorial Service;
Copy Editor (copy editing and production): Anne Lethaby, c/o Cochrane Central Production Service;
Peer‐reviewers (provided comments and recommended an editorial decision): David Torgerson, York Trials Unit, Department of Health Sciences, University of York (clinical/content review); Patrick C. Hardigan, Kiran C. Patel College of Allopathic Medicine, Nova Southeastern University (clinical/content review); Brian Duncan (consumer review); Jennifer Hilgart, Cochrane Evidence Production & Methods Directorate (methods review); Steve McDonald, Cochrane Australia (search review).
Appendices
Appendix 1. Search strategies
Original review
Search strategies were developed for use in a range of electronic bibliographic databases in Edwards 2003.
Database time period or version
Cochrane Controlled Trials Register 1999.3 CINAHL 1982 ‐ 1999.07 ERIC 1982 ‐ 1998.09 PsycLit 1887 ‐ 1999.09 Dissertation Abstracts 1861 ‐ 1999.08 MEDLINE 1966 ‐ 1999 EMBASE 1980 ‐ 1999.08
A. questionnair* or survey* or data collection B. respon* or return* C. remind* or letter* or postcard* or incentiv* or reward* or money* or monetary or payment* or lottery or raffle or prize or personalis* or sponsor* or anonym* or length or style* or format or appearance or color or colour or stationery or envelope or stamp* or postage or certified or registered or telephon* or telefon* or notice or dispatch* or deliver* or deadline or sensitive D. control* or randomi* or blind* or mask* or trial* or compar* or experiment* or "exp" or factorial E. A and B and C and D
Social Science Citation Index 1981 ‐ 1999 Science Citation Indes 1981 ‐ 1999 [(survey* or questionnair*) and (return* or respon*)]
Social Psychological Educational Criminological Trials Register (SPECTR) 1950 ‐ 1998 EconLit 1969 ‐ 2000 Sociological Abstracts 1963 ‐ 2000
((survey$ or questionn$) and (return$ or respon$)).ti or ((survey$ or questionn$) and (mail$ or post$)).ti or ((return$ or respon$) and (mail$ or post$)).ti
Index to Scientific & Technical Proceedings 1982 ‐ 2000
((survey*, questionn*)+(return*,respon*))@TI, ((return*,respon*)+(mail,mailed,postal))@TI, ((survey*,questionn*)+(mail,mailed,postal))@TI
National Research Register (Web version): 2000.1
((survey*:ti or questionn*:ti) and (return*:ti or respon*:ti)) or ((return*:ti or respon*:ti) and (mail:ti or mailed:ti or postal:ti)) or ((survey*:ti or questionn*:ti) and (mail:ti or mailed:ti or postal:ti))
The following literature reviews and meta‐analyses were inspected for eligible trials:
Armstrong JS. Monetary incentives in mail surveys. Public Opinion Quarterly 1975;39:111‐6.
Armstrong S. Return postage in mail surveys: a meta analysis. Public Opinion Quarterly 1987;51:233‐48.
Bogen K. The effects of questionnaire length on response rates ‐ a review of the literature. American Statistical Association 1996;1020‐5.
Boser JA. Reviewing the research on mail survey response rates: descriptive study. Paper presented at the annual meeting of the American Educational Research Association New York. April 1996.
Boser JA. Factors influencing mail survey response rates: What do we really know? Paper presented at the Annual meeting of the Mid‐South Educational Research Association. November 1995.
Brehm J. Stubbing our toes for a foot in the door? Prior contact, incentives and survey response. International Journal of Public Opinion Research 1994;6(1):45‐63.
Church AH. Estimating the effect of incentives on mail survey response rates: a meta‐analysis. Public Opinion Quarterly 1993;57:62‐79.
Cox WE. Response patterns to mail surveys. Journal of Marketing Research 1966;3:392‐7.
Downs PE. Recent evidence on the relationship between anonymity and response variables for mail surveys. Journal of the Academy of Marketing Science 1986;14(1):72‐82.
Duncan WJ. Mail questionnaires in survey research: a review of response inducement techniques. Journal of Management 1979;5(1):39‐55.
Erdos PL. Visible vs. disguised keying on questionnaires. Journal of Advertising Research 1977;17(1):13‐8.
Fox RJ. Mail survey response rate. A meta‐analysis of selected techniques for inducing response. Public Opinion Quarterly 1988;52:467‐91.
Francel EG. Mail‐administered questionnaires: a success story. Journal of Marketing Research 1966;3:89‐92.
Goyder JC. Further evidence on factors affecting response rates to mailed questionnaires. American Sociological Review 1982;47:550‐3.
Green KE. Reviewing the research on mail survey response rates: a meta‐analysis. Paper presented at the Annual Meeting of the American Educational Research Association. April 1996.
Greenwald HP. Issues in survey data on medical practice: some empirical comparisons. Public Health Reports 1986;101(5):514‐46.
Guffey H. Stamps versus postal permits: a decisional guide for return postage in mail questionnaires. Journal of Academy of Marketing Science 1980;8(3): 234‐42.
Harvey L. Factors affecting response rates to mailed questionnaires: a comprehensive literature review. Journal of the Market Research Society 1987;29:341‐53.
Heberlein TA. Factors affecting response rates to mailed questionnaires. American Sociological Review 1978;43(4):447‐62.
Hopkins KD. Response rates in survey research: a meta‐analysis of the effects of monetary gratuities. Journal of Experimental Education 1992;61:52‐62.
Houston MJ. Broadening the scope of methodological research on mail surveys. Journal of Marketing Research 1976;13:397‐403.
Jobber D. Improving response rates in industrial mail surveys. Industrial Marketing Management 1986;15:183‐95.
Jobber D. Modelling the effects of prepaid monetary incentives on mail survey response. Journal of the Operational Research Society 1988;39:365‐72.
Jobber D. Questionnaire factors and mail survey response rates. European Research. 1985;(July)124‐9.
Jobber D. Maximizing response rates in industrial mail surveys: a review of the evidence. Advances in Business Marketing 1990;4:121‐46.
Kanuk L. Mail surveys and response rates: a literature review. Journal of Marketing Research 1975;12:440‐53.
King FW. Anonymous versus identifiable questionnaires in drug usage surveys. American Psychologist 1970;25:982‐5.
Leslie L. Increasing response rates to long questionnaires. Journal of Educational Research 1970;63:347‐50.
Linsky AS. Stimulating responses to mailed questionnaires: a review. Public Opinion Quarterly 1975;39:82‐101.
Mayer EN. Postage stamps do affect results of your mailing. Printers' Ink 1946;217:91.
Nowack KM. Getting them out and getting them back. Training Development Journal 1990;(April)82‐5.
Ransdell LB. Maximising response rate in questionnaire research. American Journal of Health Behaviour 1996;20:50‐6.
Robin S. A procedure for securing returns to mail questionnaires. Sociology and Social Research 1965;50:24‐35
Roth PL. Response rates in HRM/OB survey research: norms and correlates, 1990‐1994. Journal of Management 1998;24:97‐117.
Schlegelmilch BB. Prenotification and mail survey response rates: a quantitative integration of the literature. Journal of the Market Research Society 1991;33(3):243‐55.
Scott C. Research on mail surveys. Journal of the Royal Statistical Society 1961;124:143‐205.
Singer E. Confidentiality assurances and response: a quantitative review of the experimental literature. Public Opinion Quarterly 1995;59: 66‐77.
Vaux A. Conducting mail surveys. Psychology Research Handbook. 1996:(Chapter 10).
Wiseman F. A reassessment of the effects of personalization on response patterns in mail wurveys. Journal of Marketing Research 1976;3I:110‐1.
Yammarino FJ. Understanding mail survey response behaviour: a meta‐analysis. Public Opinion Quarterly 1991;55: 613‐39.
Young JM. Improving survey response rates: a meta‐analysis of the effectiveness of an advance telephone prompt from a medical peer. Medical Journal of Australia 1999;170: 339.
Yu J. A quantitative review of research design effects on response rates to questionnaires. Journal of Marketing Research 1983;XX:36‐44.
Zelnio RN. Data collection techniques: mail questionnaires. American Journal of Hospital Pharmacy 1980;37:1113‐9.
The following journals were searched by hand:
Public Opinion Quarterly 1960 to 1998;
American Journal of Epidemiology 1948 to 1999.
Reliability of screening for eligible trials
The electronic bibliographic searches outlined above yielded several thousand records of potentially relevant reports that were then screened to determine eligibility. Because exclusion of reports during screening would mean that they would not be considered again, we assessed the accuracy and reliability of screening for relevant trials using the records retrieved by a search of ten databases.
A search of ten electronic bibliographic databases yielded 26,937 records of potentially relevant reports that were downloaded into a ProCite database. After removing duplicate records, there were 22,571 records of potentially relevant reports. These records were divided into six approximately equal sets (A to F) and each of four reviewers was allocated three of the sets to screen. The six sets were allocated such that two reviewers examined each record, and identification of trials by each reviewer could be compared with each of the other reviewers. Agreement between reviewers was assessed using Cohen's kappa statistic (k) which adjusts the proportion of records in which there was agreement between reviewers by the amount of agreement that is expected by chance alone. Ascertainment intersection (capture‐recapture) methods (Hook 1992) were then used to estimate the likely number of relevant records missed by all four reviewers. When screening was complete, full copies of the reports identified by at least one reviewer as potentially relevant were requested. Each report obtained was assessed independently by two reviewers for eligibility for inclusion in the systematic review. Disagreements about eligibility were referred to a third reviewer. Eligible reports were used as the 'gold standard' against which an assessment was made about the accuracy of screening by reviewers.
After screening, 301 of 22,571 records were identified by at least one reviewer as potentially relevant. Of the six possible comparisons between reviewers, kappa coefficients of agreement ranged from 0.59 (95% CI 0.56 to 0.62) to 0.93 (95% CI 0.90 to 0.96). Agreement was 'almost perfect' (k > 0.81) between two pairs, 'substantial' (k > 0.61) between three pairs, and 'moderate' (k > 0.41) between one pair. Ascertainment intersection methods suggest that, on average, pairs of reviewers missed 4% (range 0% to 6%) of potentially relevant records. In contrast, single reviewers missed on average 22% (range 3% to 55%). Twenty‐eight reports were not available by the time of the ascertainment intersection analysis. Of the 273 reports that were available, 156 (57%) met the inclusion criteria for the systematic review. Ascertainment intersection methods estimated that pairs of reviewers had missed very few eligible records (0 records missed, 95% CI 0 to 3 records). In the light of these results, we believe that very few eligible trials were inappropriately excluded during screening.
Sensitivity of combined search strategy
The sensitivity of the search strategy was assessed by handsearching the Public Opinion Quarterly and comparing the trials identified by handsearching with those identified by the combined search strategy. Of the 40 eligible trials identified by hand searching, 15 trials had been identified from electronic bibliographic databases and 23 had been identified from the reference lists of identified trials and relevant meta‐analyses. Two studies identified by handsearching were not identified by any part of the combined search strategy. On the basis of these results, electronic bibliographic database searching had a sensitivity of 38% (15/40), searching reference lists of identified trials and relevant meta‐analyses had a sensitivity of 58% (23/40), and the combined search strategy had a sensitivity of 95% (38/40), (95% CI 84% to 99%).
* Notes on study selection: The review authors did not record the number of records/references excluded or reasons for their exclusion at the full‐text stage during the development ofEdwards 2003. There were 372 included studies and 40 studies awaiting classification.
First review update
In Edwards 2007, the following databases were searched again using the appropriate strategies detailed above.
Database time period or version
Cochrane Controlled Trials Register 2002.4 CINAHL 1999.07 ‐ 2003.02 ERIC 1998.09 ‐ 2003.01 PsycLit 1999.09 ‐ 2003.02 Dissertation Abstracts 1999.08 ‐ 2003.02 MEDLINE 1999 ‐ 2003 EMBASE 1999.08 ‐ 2003.02 Science Citation Index 1999 ‐ 2003 Social Science Citation Index 1999 ‐ 2003 Social Psychological Educational Criminological Trials Register (SPECTR) 1998 ‐ 2003 EconLit 2000 ‐ 2003.01 Sociological Abstracts 2000 ‐ 2002.12 Index to Scientific & Technical Proceedings 2000 ‐ 2003 National Research Register (Web version): 2003.2
A search of these databases yielded 6423 records of potentially relevant reports that were downloaded into a ProCite database. Two reviewers examined each record so that identification of trials by each reviewer could be compared. After screening, 194 of 6423 records were identified by at least one reviewer as potentially relevant.
During the update, attempts were made to obtain sufficient information on studies awaiting assessment to be able to include or exclude them from the review. This included writing to or emailing the authors of all potentially eligible trials and those in studies awaiting assessment.
* Notes on study selection: The review authors did not record the number of records/references excluded (with reasons for exclusion) at the full‐text stage during the development ofEdwards 2007. This first update version included 372 trials. There were 40 studies awaiting classification.
Second review update
In Edwards 2009, the following databases were searched again using the appropriate strategies detailed above. The search also included electronic‐based questionnaires such as those sent via email, and online surveys.
Cochrane Library Online Issue 4 2007 CENTRAL Cochrane Library Online Issue 4 2007 Methodology studies (CMR) CINAHL 2003 ‐ 2007.12 ERIC 2003 ‐ 2007.12 PsycINFO 2003 ‐ 2008.01 MEDLINE 2003 ‐ 2007.11 EMBASE 2003 ‐ 2007.10 Science Citation Index 2003 ‐ 2008.01 Social Science Citation Index 2003 ‐ 2008.01 Social Psychological Educational Criminological Trials Register (SPECTR) 2003 ‐ 2007.12 EconLit 2003 ‐ 2007.12 Sociological Abstracts 2003 ‐ 2007.12 Dissertation & Theses 2003 ‐ 2008.01 Index to Scientific & Technical Proceedings 2003 ‐ 2008.01 National Research Register (Web version): 2008.02
A search of these databases yielded 19,826 records of potentially relevant reports that were downloaded into an EndNote database. After removing duplicates, we identified 14,792 records. Two reviewers examined each record so that identification of trials by each reviewer could be compared. After screening, 253 of 14,792 records were identified by at least one reviewer as potentially relevant and their full texts were sought.
During the update, attempts were made to obtain sufficient information on studies awaiting assessment to be able to include or exclude them from the review. This included writing to or emailing the authors of all potentially eligible trials and those studies awaiting assessment.
* Notes on study selection: The review authors did not record the number of records/references excluded (with reasons for exclusion) at the full‐text stage during the development ofEdwards 2009. This second review update included 513 trials. There were 23 studies awaiting classification.
Third review update (current version)
In 2021, an Information Specialist advised us of some adjustments to improve our search strategy. We reviewed the terms used to search each of the databases and included the additional use of Medical Subject Headings (MeSH) and Emtree terms in relevant databases, which were exploded or expanded appropriately to capture as many relevant articles as possible.
We added the RCT search filters developed by the Cochrane Collaboration, including the Cochrane Highly Sensitive Search Strategies for identifying randomised trials in MEDLINE (sensitivity‐maximising version) and controlled trials in Embase.
We used proximity searching and increased truncation of terms to increase search sensitivity while maintaining precision; searches of databases in title only were removed from the search strategy, and unnecessary restrictions were removed (e.g. MEDLINE searches were expanded to include all possible methods to increase questionnaire response by the removal of Part C of the original search strategy which had restricted results to known methods only).
Several changes to databases also occurred since the second update, so further changes were necessary: out‐of‐date sources were removed; C2‐SPECTR, Scientific & Technical Proceedings were replaced with Web of Science; trial register searches were expanded to include the Clinical Trials Register and the WHO International Clinical Trial Registry Platform. We also added databases to increase the breadth of the search: Global Index Medicus database from WHO (specialising in research from the global south) and Scopus.
Example search terms:
Ovid MEDLINE(R) ALL <1946 to August 13, 2021>
1 randomized controlled trial.pt.
2 controlled clinical trial.pt.
3 randomized.ab.
4 placebo.ab.
5 clinical trials as topic.sh.
6 randomly.ab.
7 trial.ti.
8 or/1‐7
9 ((questionnair* or survey* or (data adj1 collect*)) adj4 (respon* or return* or participat* or completion)).ti,ab,kf.
10 "Surveys and Questionnaires"/ or Data Collection/
11 exp Community Participation/sn [Statistics & Numerical Data]
12 9 or (10 and 11)
13 8 and 12
Notes:
Lines 1‐8 are the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity‐ and precision‐maximising version.
Line 9 uses proximity searching to look for terms for questionnaires within 4 words of terms for response etc.
Lines 10 and 11 use MeSH terms to look for papers on specific subjects.
Line 12 combines the topic searches together.
Line 12 finds RCTs on the topic.
Appendix 2. Conversion of odds ratios to response rates from different baseline rates
|
Odds ratio 0.50 |
0.75 | 1.00 | 1.25 | 1.50 | 1.75 | 2.00 | 2.25 | 2.50 | 2.75 | 3.00 | |
|
Baseline rate (%) 10 |
5 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 23 | 25 |
| 20 | 11 | 16 | 20 | 24 | 27 | 30 | 33 | 36 | 38 | 41 | 43 |
| 30 | 18 | 24 | 30 | 35 | 39 | 43 | 46 | 49 | 52 | 54 | 56 |
| 40 | 25 | 33 | 40 | 45 | 50 | 54 | 57 | 60 | 63 | 65 | 67 |
| 50 | 33 | 43 | 50 | 56 | 60 | 64 | 67 | 69 | 71 | 73 | 75 |
| 60 | 43 | 53 | 60 | 65 | 69 | 72 | 75 | 77 | 79 | 80 | 82 |
| 65 | 48 | 58 | 65 | 70 | 74 | 76 | 79 | 81 | 82 | 84 | 85 |
| 70 | 54 | 64 | 70 | 74 | 78 | 80 | 82 | 84 | 85 | 87 | 88 |
| 75 | 60 | 69 | 75 | 79 | 82 | 84 | 86 | 87 | 88 | 89 | 90 |
| 80 | 67 | 75 | 80 | 83 | 86 | 88 | 89 | 90 | 91 | 92 | 92 |
| 85 | 74 | 81 | 85 | 88 | 89 | 91 | 92 | 93 | 93 | 94 | 94 |
| 90 | 82 | 87 | 90 | 92 | 93 | 94 | 95 | 95 | 96 | 96 | 96 |
| 95 | 90 | 93 | 95 | 96 | 97 | 97 | 97 | 98 | 98 | 98 | 98 |
Appendix 3. Observations from the Stakeholder Advisory Group
During the 2021‐23 update, a Stakeholder Advisory Group was recruited to comment on the work as it progressed. Members of the group were drawn from a variety of disciplines and experience, including academic and action research, community development, public health, campaigning, communications, local government and local community services. The interests of SAG members in survey and questionnaire design were heavily oriented towards social science research and, in particular, to issues such as poverty and deprivation, health and disability, race and gender. Discussions were wide‐ranging and raised considerations that could only be partly accommodated during the review update, or not at all.
There was a high level of dissatisfaction, especially amongst members working in community settings, with externally generated questionnaire surveys, as opposed to surveys generated from within fieldwork practice or service delivery. Particular points included: mistrust of motivation or intent of contractors or commissioners; researchers with poor awareness of their own personal biases or prejudicial attitudes towards target populations; and identification of ‘Questionnaire fatigue’ as potential important influences.
Strong commitment to understanding of the demography and social circumstances of target audiences and proposed collection methods was identified as key factor in achieving an inclusive sample. For social science studies, one useful mechanism against which to assess survey structure and methodology can be cross‐reference to ‘protected characteristics’ embodied in the UK’s Equality Act. A 10th characteristic of poverty and declining social mobility could also be added to this.
In addition to the many aspects of questionnaire design covered in this review which are likely to influence response rates, additional considerations were raised against which the usefulness of data collected can be assessed. These included, for example, the issue of whether language, neurodiversity, and literacy issues were accommodated. There is evidence of further exclusion of some respondent cohorts by the move to online, paperless surveys.
Failure to record extraneous factors in research study design, such as different demographics, cultural assumptions, literacy, or language differences and the extent to which more marginalised groups respond, can undermine survey outcomes. The ability to interrogate ‘intersectionality’ in results can assist in drilling down to these underlying factors. The evidence of absence as well as evidence of presence can be significant.
There is a responsibility to make dissemination accessible, and to understand the power and impact of communication strategies.
Data and analyses
Comparison 1. Monetary incentive vs. no incentive.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 1.1 First response | 64 | 72237 | Odds Ratio (M‐H, Random, 95% CI) | 2.16 [1.95, 2.40] |
| 1.2 Final response | 111 | 226209 | Odds Ratio (M‐H, Random, 95% CI) | 1.86 [1.73, 1.99] |
| 1.3 e ‐ Log | 3 | 3209 | Odds Ratio (M‐H, Random, 95% CI) | 1.83 [0.91, 3.69] |
| 1.4 e ‐ Submission | 5 | 6446 | Odds Ratio (M‐H, Random, 95% CI) | 1.88 [1.31, 2.71] |
1.1. Analysis.
Comparison 1: Monetary incentive vs. no incentive, Outcome 1: First response
1.3. Analysis.
Comparison 1: Monetary incentive vs. no incentive, Outcome 3: e ‐ Log
Comparison 2. Larger vs. smaller monetary incentive.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 2.1 First response | 22 | 20722 | Odds Ratio (M‐H, Random, 95% CI) | 1.21 [1.11, 1.33] |
| 2.2 Final response | 50 | 137457 | Odds Ratio (M‐H, Random, 95% CI) | 1.24 [1.15, 1.33] |
2.1. Analysis.
Comparison 2: Larger vs. smaller monetary incentive, Outcome 1: First response
Comparison 3. Monetary vs. non‐monetary incentive.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 3.1 First response | 6 | 9589 | Odds Ratio (M‐H, Random, 95% CI) | 1.85 [1.35, 2.55] |
| 3.2 Final response | 17 | 28212 | Odds Ratio (M‐H, Random, 95% CI) | 1.67 [1.47, 1.90] |
| 3.3 e ‐ Login | 1 | 1100 | Odds Ratio (M‐H, Random, 95% CI) | 0.66 [0.50, 0.87] |
| 3.4 e ‐ Submission | 3 | 3614 | Odds Ratio (M‐H, Random, 95% CI) | 0.89 [0.63, 1.26] |
3.1. Analysis.
Comparison 3: Monetary vs. non‐monetary incentive, Outcome 1: First response
3.3. Analysis.
Comparison 3: Monetary vs. non‐monetary incentive, Outcome 3: e ‐ Login
Comparison 4. Non‐monetary incentive vs. no incentive.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 4.1 First response | 74 | 117750 | Odds Ratio (M‐H, Random, 95% CI) | 1.20 [1.13, 1.27] |
| 4.2 Final response | 146 | 277802 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [1.11, 1.21] |
| 4.3 e ‐ Login | 6 | 22565 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [1.10, 1.28] |
| 4.4 e ‐ Submission | 16 | 38901 | Odds Ratio (M‐H, Random, 95% CI) | 1.60 [1.25, 2.05] |
4.1. Analysis.
Comparison 4: Non‐monetary incentive vs. no incentive, Outcome 1: First response
4.3. Analysis.
Comparison 4: Non‐monetary incentive vs. no incentive, Outcome 3: e ‐ Login
Comparison 5. Larger non‐monetary incentive vs. smaller.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 5.1 First response | 4 | 7570 | Odds Ratio (M‐H, Random, 95% CI) | 1.31 [1.15, 1.49] |
| 5.2 Final response | 11 | 18688 | Odds Ratio (M‐H, Random, 95% CI) | 1.15 [1.00, 1.33] |
| 5.3 e ‐ Login | 4 | 13250 | Odds Ratio (M‐H, Random, 95% CI) | 1.18 [1.00, 1.38] |
| 5.4 e ‐ Submission | 10 | 37382 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.87, 1.32] |
5.1. Analysis.
Comparison 5: Larger non‐monetary incentive vs. smaller, Outcome 1: First response
5.3. Analysis.
Comparison 5: Larger non‐monetary incentive vs. smaller, Outcome 3: e ‐ Login
Comparison 6. Unconditional incentive vs. conditional.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 6.1 First response | 16 | 29435 | Odds Ratio (M‐H, Random, 95% CI) | 1.83 [1.48, 2.25] |
| 6.2 Final response | 35 | 48850 | Odds Ratio (M‐H, Random, 95% CI) | 1.53 [1.35, 1.74] |
| 6.3 e ‐ Log | 1 | 736 | Odds Ratio (M‐H, Random, 95% CI) | 0.90 [0.64, 1.27] |
| 6.4 e ‐ Submission | 3 | 1401 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.77, 1.50] |
6.1. Analysis.
Comparison 6: Unconditional incentive vs. conditional, Outcome 1: First response
6.3. Analysis.
Comparison 6: Unconditional incentive vs. conditional, Outcome 3: e ‐ Log
Comparison 7. Incentive with first vs. subsequent mailing.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 7.1 First response | 4 | 8942 | Odds Ratio (M‐H, Random, 95% CI) | 1.96 [1.53, 2.53] |
| 7.2 Final response | 4 | 8942 | Odds Ratio (M‐H, Random, 95% CI) | 1.14 [1.03, 1.26] |
7.1. Analysis.
Comparison 7: Incentive with first vs. subsequent mailing, Outcome 1: First response
Comparison 8. Offer of survey results vs. no offer.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 8.1 First response | 7 | 11095 | Odds Ratio (M‐H, Random, 95% CI) | 1.01 [0.85, 1.20] |
| 8.2 Final response | 13 | 20052 | Odds Ratio (M‐H, Random, 95% CI) | 0.91 [0.78, 1.05] |
| 8.3 e ‐ Submission | 2 | 2884 | Odds Ratio (M‐H, Random, 95% CI) | 1.36 [1.16, 1.59] |
8.1. Analysis.
Comparison 8: Offer of survey results vs. no offer, Outcome 1: First response
Comparison 9. Pen vs. no pen.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 9.1 First Response | 12 | 31820 | Odds Ratio (M‐H, Random, 95% CI) | 1.31 [1.16, 1.47] |
| 9.2 Final Response | 14 | 46096 | Odds Ratio (M‐H, Random, 95% CI) | 1.32 [1.14, 1.53] |
9.1. Analysis.
Comparison 9: Pen vs. no pen, Outcome 1: First Response
Comparison 10. Cheap pen vs. expensive pen.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 10.1 First response | 1 | 6167 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.81, 1.31] |
| 10.2 Final Response | 1 | 6167 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.81, 1.31] |
10.1. Analysis.
Comparison 10: Cheap pen vs. expensive pen, Outcome 1: First response
Comparison 11. Boxed pen vs. unboxed.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 11.1 First Response | 1 | 6167 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [1.00, 1.22] |
| 11.2 Final Response | 1 | 6167 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [1.00, 1.22] |
11.1. Analysis.
Comparison 11: Boxed pen vs. unboxed, Outcome 1: First Response
Comparison 12. Monetary incentive with follow‐up vs. no incentive with follow‐up.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 12.1 First response | 1 | 2342 | Odds Ratio (M‐H, Random, 95% CI) | 0.99 [0.84, 1.17] |
| 12.2 Final response | 1 | 2342 | Odds Ratio (M‐H, Random, 95% CI) | 0.97 [0.82, 1.16] |
12.1. Analysis.
Comparison 12: Monetary incentive with follow‐up vs. no incentive with follow‐up, Outcome 1: First response
Comparison 13. Non‐monetary incentive vs. charitable donation.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 13.1 Final response | 1 | 444 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [0.98, 2.12] |
Comparison 14. Cheque incentive requiring ID vs. no ID.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 14.1 Final response | 1 | 531 | Odds Ratio (M‐H, Random, 95% CI) | 0.75 [0.41, 1.37] |
Comparison 15. Study brochure vs. no brochure.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 15.1 First response | 3 | 7908 | Odds Ratio (M‐H, Random, 95% CI) | 0.89 [0.64, 1.24] |
| 15.3 Final response | 11 | 19981 | Odds Ratio (M‐H, Random, 95% CI) | 0.97 [0.83, 1.13] |
15.1. Analysis.
Comparison 15: Study brochure vs. no brochure, Outcome 1: First response
Comparison 16. Cheque incentive vs. cashcard.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 16.2 First Response | 1 | 303 | Odds Ratio (M‐H, Random, 95% CI) | 1.81 [1.15, 2.86] |
Comparison 17. Single cash note vs. multiple notes.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 17.2 Final Response | 1 | 2856 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.94, 1.26] |
Comparison 18. Higher denominations in monetary lottery incentives vs. lower.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 18.1 e ‐ Submission | 2 | 4721 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.87, 1.14] |
Comparison 19. Unconditional and conditional incentives vs. conditional incentives.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 19.1 e ‐ Submission | 1 | 1061 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.92, 1.54] |
Comparison 20. Immediate notification of lottery results vs. delayed notification.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 20.1 e ‐ Submission | 1 | 2233 | Odds Ratio (M‐H, Random, 95% CI) | 1.37 [1.13, 1.65] |
Comparison 21. Unconditional and conditional incentives vs. unconditional incentive.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 21.3 e ‐ Login | 1 | 3000 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [1.00, 1.36] |
| 21.4 e ‐ Submission | 1 | 3000 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [1.06, 1.44] |
21.3. Analysis.
Comparison 21: Unconditional and conditional incentives vs. unconditional incentive, Outcome 3: e ‐ Login
Comparison 22. Electronic with game vs. no game.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 22.2 Final Response | 1 | 130 | Odds Ratio (M‐H, Random, 95% CI) | 0.51 [0.19, 1.40] |
Comparison 23. More vs. less personalised.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 23.1 First response | 40 | 38004 | Odds Ratio (M‐H, Random, 95% CI) | 1.22 [1.11, 1.33] |
| 23.2 Final response | 74 | 97674 | Odds Ratio (M‐H, Random, 95% CI) | 1.15 [1.09, 1.21] |
| 23.3 e ‐ Login | 5 | 24557 | Odds Ratio (M‐H, Random, 95% CI) | 1.26 [1.13, 1.40] |
| 23.4 e ‐ Submission | 12 | 48910 | Odds Ratio (M‐H, Random, 95% CI) | 1.24 [1.17, 1.32] |
23.1. Analysis.
Comparison 23: More vs. less personalised, Outcome 1: First response
23.3. Analysis.
Comparison 23: More vs. less personalised, Outcome 3: e ‐ Login
Comparison 24. Handwritten vs. typed/facsimile/scanned/printed signature on covering letter.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 24.1 First response | 1 | 590 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.75, 1.54] |
| 24.2 Final response | 14 | 15006 | Odds Ratio (M‐H, Random, 95% CI) | 1.24 [1.08, 1.41] |
24.1. Analysis.
Comparison 24: Handwritten vs. typed/facsimile/scanned/printed signature on covering letter, Outcome 1: First response
Comparison 25. Handwritten address vs. computer‐printed.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 25.1 First response | 4 | 1789 | Odds Ratio (M‐H, Random, 95% CI) | 1.35 [1.04, 1.74] |
| 25.2 Final response | 9 | 6030 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [1.09, 1.37] |
25.1. Analysis.
Comparison 25: Handwritten address vs. computer‐printed, Outcome 1: First response
Comparison 26. Signed vs. unsigned.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 26.1 First response | 1 | 334 | Odds Ratio (M‐H, Random, 95% CI) | 1.38 [0.86, 2.22] |
| 26.2 Final response | 3 | 1364 | Odds Ratio (M‐H, Random, 95% CI) | 1.35 [1.04, 1.76] |
26.1. Analysis.
Comparison 26: Signed vs. unsigned, Outcome 1: First response
Comparison 27. Identifying feature on return vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 27.1 First response | 5 | 3923 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.72, 1.39] |
| 27.2 Final response | 10 | 5297 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.81, 1.32] |
27.1. Analysis.
Comparison 27: Identifying feature on return vs. none, Outcome 1: First response
Comparison 28. Identifying number on return vs. other identifier.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 28.1 First response | 1 | 741 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.68, 1.46] |
| 28.2 Final response | 1 | 741 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.68, 1.46] |
28.1. Analysis.
Comparison 28: Identifying number on return vs. other identifier, Outcome 1: First response
Comparison 29. Coloured vs. white questionnaire.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 29.1 First response | 6 | 14005 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.99, 1.15] |
| 29.2 Final response | 15 | 43754 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.98, 1.09] |
29.1. Analysis.
Comparison 29: Coloured vs. white questionnaire, Outcome 1: First response
Comparison 30. Coloured vs. standard (black/blue) ink.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 30.1 First response | 2 | 6064 | Odds Ratio (M‐H, Random, 95% CI) | 1.25 [1.03, 1.53] |
| 30.2 Final response | 3 | 7040 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [0.95, 1.42] |
30.1. Analysis.
Comparison 30: Coloured vs. standard (black/blue) ink, Outcome 1: First response
Comparison 31. Coloured vs. black & white letterhead.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 31.1 First response | 1 | 1650 | Odds Ratio (M‐H, Random, 95% CI) | 0.99 [0.80, 1.24] |
| 31.2 Final response | 2 | 2356 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.91, 1.28] |
31.1. Analysis.
Comparison 31: Coloured vs. black & white letterhead, Outcome 1: First response
Comparison 32. Illustration on cover of q'aire largely in black vs. largely in white.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 32.1 Final response | 1 | 320 | Odds Ratio (M‐H, Random, 95% CI) | 1.62 [1.04, 2.53] |
Comparison 33. Folder or booklet vs. stapled pages.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 33.1 First response | 2 | 1845 | Odds Ratio (M‐H, Random, 95% CI) | 1.17 [0.94, 1.45] |
| 33.2 Final response | 3 | 5681 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.99, 1.23] |
33.1. Analysis.
Comparison 33: Folder or booklet vs. stapled pages, Outcome 1: First response
Comparison 34. Large paper size vs. small.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 34.1 First response | 1 | 2000 | Odds Ratio (M‐H, Random, 95% CI) | 0.83 [0.67, 1.03] |
| 34.2 Final response | 2 | 2145 | Odds Ratio (M‐H, Random, 95% CI) | 0.88 [0.56, 1.39] |
34.1. Analysis.
Comparison 34: Large paper size vs. small, Outcome 1: First response
Comparison 35. Dot matrix print vs. letter quality print.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 35.1 Final response | 1 | 176 | Odds Ratio (M‐H, Random, 95% CI) | 1.15 [0.63, 2.10] |
Comparison 36. Questionnaire printed on high vs. standard quality paper or thick paper vs. thin.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 36.1 Final response | 3 | 3372 | Odds Ratio (M‐H, Random, 95% CI) | 0.83 [0.68, 1.02] |
Comparison 37. Single vs. double‐sided questionnaire.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 37.1 First response | 2 | 5025 | Odds Ratio (M‐H, Random, 95% CI) | 1.14 [0.95, 1.36] |
| 37.2 Final response | 5 | 9383 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [1.02, 1.25] |
37.1. Analysis.
Comparison 37: Single vs. double‐sided questionnaire, Outcome 1: First response
Comparison 38. Large font size vs. small.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 38.1 Final response | 1 | 650 | Odds Ratio (M‐H, Random, 95% CI) | 1.26 [0.87, 1.82] |
Comparison 39. Study logo on several items in the mailing package vs. on questionnaire only.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 39.1 Final response | 1 | 1000 | Odds Ratio (M‐H, Random, 95% CI) | 0.92 [0.72, 1.18] |
Comparison 40. Picture of researcher/images vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 40.1 First response | 2 | 630 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.72, 1.69] |
| 40.2 Final response | 5 | 3956 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.70, 1.51] |
| 40.3 e ‐ Submission | 2 | 720 | Odds Ratio (M‐H, Random, 95% CI) | 3.05 [1.84, 5.06] |
40.1. Analysis.
Comparison 40: Picture of researcher/images vs. none, Outcome 1: First response
Comparison 41. Attractive vs. less attractive picture.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 41.1 e ‐ Submission | 2 | 520 | Odds Ratio (M‐H, Random, 95% CI) | 3.44 [0.72, 16.49] |
Comparison 42. Cartoons included vs. not included.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 42.1 Final response | 1 | 280 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.62, 1.62] |
Comparison 43. Professional design vs. standard.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 43.1 First response | 2 | 2904 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.58, 1.72] |
| 43.2 Final outcome | 2 | 2904 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.58, 1.72] |
43.1. Analysis.
Comparison 43: Professional design vs. standard, Outcome 1: First response
Comparison 44. Personalised SMS reminder vs. standard SMS reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 44.1 First Response | 2 | 901 | Odds Ratio (M‐H, Random, 95% CI) | 1.37 [1.00, 1.88] |
| 44.2 Final Response | 2 | 901 | Odds Ratio (M‐H, Random, 95% CI) | 1.53 [0.97, 2.43] |
44.1. Analysis.
Comparison 44: Personalised SMS reminder vs. standard SMS reminder, Outcome 1: First Response
Comparison 45. "Action Required" subject line vs. "Reminder".
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 45.1 First response | 1 | 231 | Odds Ratio (M‐H, Random, 95% CI) | 0.49 [0.28, 0.83] |
| 45.2 Final response | 1 | 231 | Odds Ratio (M‐H, Random, 95% CI) | 0.61 [0.23, 1.63] |
45.1. Analysis.
Comparison 45: "Action Required" subject line vs. "Reminder", Outcome 1: First response
Comparison 46. Message about incentive on envelope vs. no message.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 46.1 First response | 2 | 3895 | Odds Ratio (M‐H, Random, 95% CI) | 0.92 [0.75, 1.14] |
| 46.2 Final response | 2 | 3895 | Odds Ratio (M‐H, Random, 95% CI) | 0.91 [0.80, 1.04] |
46.1. Analysis.
Comparison 46: Message about incentive on envelope vs. no message, Outcome 1: First response
Comparison 47. Health message vs. monetary message.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 47.1 First response | 1 | 1569 | Odds Ratio (M‐H, Random, 95% CI) | 1.11 [0.91, 1.35] |
| 47.2 Final response | 1 | 1569 | Odds Ratio (M‐H, Random, 95% CI) | 1.05 [0.86, 1.29] |
47.1. Analysis.
Comparison 47: Health message vs. monetary message, Outcome 1: First response
Comparison 48. Teaser on envelope vs. no teaser.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 48.1 First response | 3 | 4013 | Odds Ratio (M‐H, Random, 95% CI) | 1.45 [0.96, 2.20] |
| 48.2 Final response | 5 | 23621 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.95, 1.22] |
48.1. Analysis.
Comparison 48: Teaser on envelope vs. no teaser, Outcome 1: First response
Comparison 49. More readable/concise/info mapped letter vs. standard.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 49.2 Final response | 2 | 1678 | Odds Ratio (M‐H, Random, 95% CI) | 0.88 [0.72, 1.09] |
Comparison 50. Logo sticker on envelope vs. no sticker.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 50.1 First response | 1 | 517 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.75, 1.49] |
Comparison 51. Subject line vs. blank.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 51.1 e ‐ Login | 2 | 6152 | Odds Ratio (M‐H, Random, 95% CI) | 0.83 [0.70, 0.99] |
| 51.2 e ‐ Submission | 2 | 6152 | Odds Ratio (M‐H, Random, 95% CI) | 0.84 [0.71, 1.01] |
51.1. Analysis.
Comparison 51: Subject line vs. blank, Outcome 1: e ‐ Login
Comparison 52. "Survey" subject line vs. blank.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 52.1 e ‐ Login | 2 | 3845 | Odds Ratio (M‐H, Random, 95% CI) | 0.80 [0.67, 0.97] |
| 52.2 e ‐ Submission | 2 | 3845 | Odds Ratio (M‐H, Random, 95% CI) | 0.81 [0.67, 0.97] |
52.1. Analysis.
Comparison 52: "Survey" subject line vs. blank, Outcome 1: e ‐ Login
Comparison 53. Text vs. HTML file formats.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 53.1 e ‐ Submission | 1 | 6090 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.84, 1.19] |
Comparison 54. White background vs. black.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 54.1 e ‐ Submission | 1 | 6090 | Odds Ratio (M‐H, Random, 95% CI) | 1.31 [1.10, 1.56] |
Comparison 55. Header vs. no header.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 55.1 e ‐ Submission | 1 | 6090 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [0.90, 1.41] |
Comparison 56. Simple vs. complex header.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 56.1 e ‐ Submission | 1 | 5075 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [1.03, 1.48] |
Comparison 57. Textual presentation of response categories vs. visual presentation.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 57.1 e ‐ Submission | 1 | 5413 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [1.05, 1.36] |
Comparison 58. Scrollable web page vs. multiple web pages.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 58.1 Final response | 1 | 517 | Odds Ratio (M‐H, Random, 95% CI) | 0.93 [0.66, 1.32] |
Comparison 59. Subject line emphasises incentive vs. no emphasis.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 59.1 e ‐ Login | 2 | 3676 | Odds Ratio (M‐H, Random, 95% CI) | 2.32 [0.59, 9.13] |
| 59.2 e ‐ Submission | 2 | 3676 | Odds Ratio (M‐H, Random, 95% CI) | 2.19 [0.58, 8.27] |
59.1. Analysis.
Comparison 59: Subject line emphasises incentive vs. no emphasis, Outcome 1: e ‐ Login
Comparison 60. Email reminder including humour vs. standard email.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 60.1 e ‐ Submission | 1 | 2963 | Odds Ratio (M‐H, Random, 95% CI) | 1.17 [0.99, 1.38] |
Comparison 61. Stamped vs. franked outward envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 61.1 First response | 2 | 930 | Odds Ratio (M‐H, Random, 95% CI) | 1.04 [0.79, 1.37] |
| 61.2 Final response | 6 | 13964 | Odds Ratio (M‐H, Random, 95% CI) | 0.95 [0.88, 1.03] |
61.1. Analysis.
Comparison 61: Stamped vs. franked outward envelope, Outcome 1: First response
Comparison 62. First vs. second/third class outward mailing.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 62.1 First response | 1 | 7370 | Odds Ratio (M‐H, Random, 95% CI) | 1.12 [1.02, 1.23] |
| 62.2 Final response | 2 | 8300 | Odds Ratio (M‐H, Random, 95% CI) | 1.11 [1.02, 1.21] |
62.1. Analysis.
Comparison 62: First vs. second/third class outward mailing, Outcome 1: First response
Comparison 63. Commemorative/race‐specific vs. ordinary stamp on return envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 63.1 First response | 3 | 2430 | Odds Ratio (M‐H, Random, 95% CI) | 0.91 [0.66, 1.24] |
| 63.2 Final response | 5 | 5461 | Odds Ratio (M‐H, Random, 95% CI) | 0.92 [0.81, 1.06] |
63.1. Analysis.
Comparison 63: Commemorative/race‐specific vs. ordinary stamp on return envelope, Outcome 1: First response
Comparison 64. Certified/special delivery vs. regular outward mailing.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 64.1 First response | 12 | 18075 | Odds Ratio (M‐H, Random, 95% CI) | 2.12 [1.61, 2.79] |
| 64.2 Final response | 19 | 30492 | Odds Ratio (M‐H, Random, 95% CI) | 1.68 [1.36, 2.08] |
64.1. Analysis.
Comparison 64: Certified/special delivery vs. regular outward mailing, Outcome 1: First response
Comparison 65. Stamped return vs. business reply/franked envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 65.1 First response | 16 | 34172 | Odds Ratio (M‐H, Random, 95% CI) | 1.21 [1.12, 1.32] |
| 65.2 Final response | 28 | 55550 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [1.13, 1.33] |
65.1. Analysis.
Comparison 65: Stamped return vs. business reply/franked envelope, Outcome 1: First response
Comparison 66. Priority stamps vs. first‐class stamps on return envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 66.1 Final response | 1 | 205 | Odds Ratio (M‐H, Random, 95% CI) | 0.26 [0.14, 0.46] |
Comparison 67. First vs. second‐class stamp on return envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 67.1 Final response | 1 | 800 | Odds Ratio (M‐H, Random, 95% CI) | 0.91 [0.69, 1.21] |
Comparison 68. Multiple stamps vs. single stamp on return envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 68.1 Final response | 1 | 510 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [1.01, 2.04] |
Comparison 69. Pre‐paid return envelope vs. not pre‐paid.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 69.1 First response | 3 | 2740 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [0.78, 1.95] |
| 69.2 Final response | 4 | 4094 | Odds Ratio (M‐H, Random, 95% CI) | 1.09 [0.71, 1.68] |
69.1. Analysis.
Comparison 69: Pre‐paid return envelope vs. not pre‐paid, Outcome 1: First response
Comparison 70. Stamped addressed return envelope vs. address label only included.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 70.1 Final response | 1 | 147 | Odds Ratio (M‐H, Random, 95% CI) | 0.86 [0.45, 1.65] |
Comparison 71. Questionnaire sent to work vs. home address.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 71.1 First response | 2 | 1140 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [0.89, 1.52] |
| 71.2 Final response | 2 | 1140 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [0.89, 1.52] |
71.1. Analysis.
Comparison 71: Questionnaire sent to work vs. home address, Outcome 1: First response
Comparison 72. Window vs. regular envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 72.1 First response | 2 | 11781 | Odds Ratio (M‐H, Random, 95% CI) | 0.85 [0.68, 1.06] |
| 72.2 Final response | 2 | 11781 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.61, 1.49] |
72.1. Analysis.
Comparison 72: Window vs. regular envelope, Outcome 1: First response
Comparison 73. Q'aire mailed in large vs. standard/small envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 73.1 Final response | 1 | 1200 | Odds Ratio (M‐H, Random, 95% CI) | 0.93 [0.74, 1.17] |
Comparison 74. Questionnaire mailed on Monday vs. Friday.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 74.1 First response | 2 | 1843 | Odds Ratio (M‐H, Random, 95% CI) | 0.84 [0.70, 1.01] |
| 74.2 Final response | 2 | 1843 | Odds Ratio (M‐H, Random, 95% CI) | 0.84 [0.70, 1.01] |
74.1. Analysis.
Comparison 74: Questionnaire mailed on Monday vs. Friday, Outcome 1: First response
Comparison 75. Questionnaire received on Monday/Tuesday vs. Friday.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 75.1 Final response | 1 | 460 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.64, 1.56] |
| 75.2 e ‐ Login | 1 | 1943 | Odds Ratio (M‐H, Random, 95% CI) | 1.12 [0.80, 1.57] |
| 75.3 e ‐ Submission | 1 | 1943 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.66, 1.40] |
75.2. Analysis.
Comparison 75: Questionnaire received on Monday/Tuesday vs. Friday, Outcome 2: e ‐ Login
Comparison 76. Q'aire sent 1‐5 weeks vs. 9‐14 weeks after hospital discharge.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 76.1 Final response | 2 | 2324 | Odds Ratio (M‐H, Random, 95% CI) | 2.26 [0.69, 7.37] |
Comparison 77. Padded envelope vs. priority mail envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 77.1 First response | 1 | 1600 | Odds Ratio (M‐H, Random, 95% CI) | 0.88 [0.72, 1.07] |
Comparison 78. Hand delivery by known person vs. postal delivery.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 78.1 Final response | 1 | 135 | Odds Ratio (M‐H, Random, 95% CI) | 2.60 [1.29, 5.23] |
Comparison 79. Hand delivery vs. postal delivery.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 79.1 Final response | 2 | 937 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [0.50, 4.15] |
Comparison 80. Postal vs. fax.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 80.1 First Response | 1 | 199 | Odds Ratio (M‐H, Random, 95% CI) | 0.58 [0.29, 1.14] |
| 80.2 Final Response | 1 | 199 | Odds Ratio (M‐H, Random, 95% CI) | 0.58 [0.29, 1.14] |
80.1. Analysis.
Comparison 80: Postal vs. fax, Outcome 1: First Response
Comparison 81. Postal vs. electronic.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 81.1 First Response | 21 | 62576 | Odds Ratio (M‐H, Random, 95% CI) | 1.93 [1.36, 2.72] |
| 81.2 Final Response | 27 | 66118 | Odds Ratio (M‐H, Random, 95% CI) | 1.76 [1.34, 2.32] |
81.1. Analysis.
Comparison 81: Postal vs. electronic, Outcome 1: First Response
Comparison 82. Choice (electronic/postal) vs. only postal response.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 82.1 First response | 4 | 19983 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.96, 1.09] |
| 82.2 Final response | 8 | 20909 | Odds Ratio (M‐H, Random, 95% CI) | 0.94 [0.86, 1.02] |
82.1. Analysis.
Comparison 82: Choice (electronic/postal) vs. only postal response, Outcome 1: First response
Comparison 83. Postal with electronic follow‐up vs. electronic with postal follow‐up.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 83.1 First response | 3 | 2325 | Odds Ratio (M‐H, Random, 95% CI) | 1.45 [0.31, 6.70] |
| 83.2 Final response | 4 | 2958 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.76, 1.87] |
83.1. Analysis.
Comparison 83: Postal with electronic follow‐up vs. electronic with postal follow‐up, Outcome 1: First response
Comparison 84. Electronic vs. choice (postal/electronic).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 84.1 First response | 9 | 45079 | Odds Ratio (M‐H, Random, 95% CI) | 0.56 [0.39, 0.80] |
| 84.2 Final response | 10 | 39523 | Odds Ratio (M‐H, Random, 95% CI) | 1.63 [1.18, 2.26] |
84.1. Analysis.
Comparison 84: Electronic vs. choice (postal/electronic), Outcome 1: First response
Comparison 85. Pre‐selected choice vs. choice.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 85.2 Final response | 1 | 6188 | Odds Ratio (M‐H, Random, 95% CI) | 1.59 [1.43, 1.77] |
Comparison 86. Mobile‐based web survey vs. computer.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 86.1 Started questionnaire | 1 | 2774 | Odds Ratio (M‐H, Random, 95% CI) | 1.58 [1.32, 1.89] |
| 86.2 Completed questionnaire | 1 | 2774 | Odds Ratio (M‐H, Random, 95% CI) | 1.62 [1.36, 1.94] |
86.1. Analysis.
Comparison 86: Mobile‐based web survey vs. computer, Outcome 1: Started questionnaire
Comparison 87. Mobile and web vs. paper and email.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 87.1 First Response | 1 | 620 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.50, 2.08] |
| 87.2 Final Response | 1 | 620 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.50, 2.08] |
87.1. Analysis.
Comparison 87: Mobile and web vs. paper and email, Outcome 1: First Response
Comparison 88. Electronic vs. fax.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 88.1 First Response | 1 | 195 | Odds Ratio (M‐H, Random, 95% CI) | 3.87 [2.00, 7.49] |
| 88.2 Final Response | 1 | 195 | Odds Ratio (M‐H, Random, 95% CI) | 3.87 [2.00, 7.49] |
88.1. Analysis.
Comparison 88: Electronic vs. fax, Outcome 1: First Response
Comparison 89. SMS vs. postal.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 89.2 Final Response | 1 | 382 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.60, 2.32] |
Comparison 90. Emails and reminders sent on varying vs. fixed days.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 90.2 Final response | 1 | 21473 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [1.03, 1.14] |
Comparison 91. Emails and reminders sent on best predicted days vs. fixed days.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 91.2 Final response | 1 | 21531 | Odds Ratio (M‐H, Random, 95% CI) | 1.05 [1.00, 1.11] |
Comparison 92. Electronic with mail FU vs. electronic with interactive voice response FU.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 92.2 Final response | 1 | 1999 | Odds Ratio (M‐H, Random, 95% CI) | 1.77 [1.48, 2.11] |
Comparison 93. SMS vs. web.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 93.2 Final Response | 1 | 353 | Odds Ratio (M‐H, Random, 95% CI) | 0.68 [0.31, 1.49] |
Comparison 94. Pre‐contact vs. no pre‐contact.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 94.1 First response | 37 | 1362390 | Odds Ratio (M‐H, Random, 95% CI) | 1.32 [1.16, 1.49] |
| 94.2 Final response | 59 | 89146 | Odds Ratio (M‐H, Random, 95% CI) | 1.36 [1.23, 1.51] |
| 94.3 e ‐ Login | 2 | 1199 | Odds Ratio (M‐H, Random, 95% CI) | 1.30 [0.74, 2.26] |
| 94.4 e ‐ Submission | 3 | 3049 | Odds Ratio (M‐H, Random, 95% CI) | 1.85 [0.99, 3.45] |
94.1. Analysis.
Comparison 94: Pre‐contact vs. no pre‐contact, Outcome 1: First response
94.3. Analysis.
Comparison 94: Pre‐contact vs. no pre‐contact, Outcome 3: e ‐ Login
Comparison 95. Pre‐contact by phone vs. mail.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 95.1 First response | 3 | 978 | Odds Ratio (M‐H, Random, 95% CI) | 1.40 [1.02, 1.93] |
| 95.2 Final response | 7 | 3322 | Odds Ratio (M‐H, Random, 95% CI) | 1.18 [0.77, 1.80] |
95.1. Analysis.
Comparison 95: Pre‐contact by phone vs. mail, Outcome 1: First response
Comparison 96. Follow‐up vs. no follow‐up.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 96.1 First response | 13 | 1315514 | Odds Ratio (M‐H, Random, 95% CI) | 1.52 [1.25, 1.84] |
| 96.2 Final response | 24 | 53555 | Odds Ratio (M‐H, Random, 95% CI) | 1.33 [1.18, 1.49] |
96.1. Analysis.
Comparison 96: Follow‐up vs. no follow‐up, Outcome 1: First response
Comparison 97. Postal follow‐up including vs. excluding q'aire.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 97.1 First response | 7 | 6108 | Odds Ratio (M‐H, Random, 95% CI) | 1.22 [0.94, 1.60] |
| 97.2 Final response | 13 | 11456 | Odds Ratio (M‐H, Random, 95% CI) | 1.41 [1.13, 1.77] |
97.1. Analysis.
Comparison 97: Postal follow‐up including vs. excluding q'aire, Outcome 1: First response
Comparison 98. Follow‐up by phone vs. mail.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 98.1 First Response | 5 | 2631 | Odds Ratio (M‐H, Random, 95% CI) | 0.82 [0.48, 1.39] |
| 98.2 Final Response | 8 | 4057 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.76, 1.38] |
98.1. Analysis.
Comparison 98: Follow‐up by phone vs. mail, Outcome 1: First Response
Comparison 99. Telephone reminder vs. no reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 99.1 First response | 2 | 1364 | Odds Ratio (M‐H, Random, 95% CI) | 15.57 [0.59, 410.80] |
| 99.2 Final response | 4 | 15143 | Odds Ratio (M‐H, Random, 95% CI) | 1.96 [1.03, 3.74] |
99.1. Analysis.
Comparison 99: Telephone reminder vs. no reminder, Outcome 1: First response
Comparison 100. Higher frequency follow‐up interval vs. lower.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 100.1 First response | 2 | 1608 | Odds Ratio (M‐H, Random, 95% CI) | 0.87 [0.50, 1.50] |
| 100.2 Final response | 6 | 7520 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [1.02, 1.25] |
100.1. Analysis.
Comparison 100: Higher frequency follow‐up interval vs. lower, Outcome 1: First response
Comparison 101. Pre‐contact by letter vs. postcard.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 101.1 First Response | 1 | 780 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.80, 1.43] |
| 101.2 Final Response | 1 | 780 | Odds Ratio (M‐H, Random, 95% CI) | 0.98 [0.74, 1.30] |
| 101.3 e‐Submission | 1 | 500 | Odds Ratio (M‐H, Fixed, 95% CI) | 1.38 [0.76, 2.49] |
101.1. Analysis.
Comparison 101: Pre‐contact by letter vs. postcard, Outcome 1: First Response
Comparison 102. Pre‐contact letter vs email.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 102.1 First Response | 1 | 581 | Odds Ratio (M‐H, Random, 95% CI) | 1.27 [0.71, 2.27] |
| 102.2 Final Response | 1 | 581 | Odds Ratio (M‐H, Random, 95% CI) | 1.25 [0.83, 1.88] |
102.1. Analysis.
Comparison 102: Pre‐contact letter vs email, Outcome 1: First Response
Comparison 103. Pre‐contact by fax vs. mail.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 103.1 First response | 1 | 930 | Odds Ratio (M‐H, Random, 95% CI) | 1.01 [0.74, 1.36] |
| 103.2 Final response | 1 | 930 | Odds Ratio (M‐H, Random, 95% CI) | 0.92 [0.71, 1.20] |
103.1. Analysis.
Comparison 103: Pre‐contact by fax vs. mail, Outcome 1: First response
Comparison 104. Electronic reminder vs. no reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 104.1 First response | 2 | 582 | Odds Ratio (M‐H, Random, 95% CI) | 1.80 [0.88, 3.68] |
| 104.2 Final response | 2 | 582 | Odds Ratio (M‐H, Random, 95% CI) | 1.80 [0.88, 3.68] |
104.1. Analysis.
Comparison 104: Electronic reminder vs. no reminder, Outcome 1: First response
Comparison 105. Push‐to‐web (web, web/paper reminder) vs. mail push (mail, mail/web reminder).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 105.2 Final Response | 2 | 3824 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.87, 1.39] |
Comparison 106. Postal vs mixed‐mode reminder (electronic/postal).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 106.1 Final Response | 4 | 3998 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [0.83, 1.52] |
Comparison 107. Telephone reminder vs. standard reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 107.1 First Response | 1 | 176 | Odds Ratio (M‐H, Random, 95% CI) | 2.29 [1.17, 4.51] |
| 107.2 Final Response | 4 | 520 | Odds Ratio (M‐H, Random, 95% CI) | 1.63 [1.06, 2.50] |
107.1. Analysis.
Comparison 107: Telephone reminder vs. standard reminder, Outcome 1: First Response
Comparison 108. Email invitation to web survey vs. postal invitation.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 108.1 First Response | 3 | 18748 | Odds Ratio (M‐H, Random, 95% CI) | 2.26 [2.03, 2.53] |
| 108.2 Final Response | 5 | 24373 | Odds Ratio (M‐H, Random, 95% CI) | 1.81 [0.81, 4.01] |
108.1. Analysis.
Comparison 108: Email invitation to web survey vs. postal invitation, Outcome 1: First Response
Comparison 109. Intensive follow‐up vs. limited.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 109.1 Final response | 1 | 431 | Odds Ratio (M‐H, Random, 95% CI) | 1.69 [0.93, 3.06] |
Comparison 110. Pre‐notification SMS vs. post‐notification SMS.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 110.2 Final response | 2 | 771 | Odds Ratio (M‐H, Random, 95% CI) | 1.29 [0.66, 2.54] |
Comparison 111. Electronic with postal reminder vs. postal with electronic reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 111.2 Final Response | 1 | 5837 | Odds Ratio (M‐H, Random, 95% CI) | 1.05 [0.95, 1.16] |
Comparison 112. Study calendar with prompts vs. no calendar.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 112.2 Final Response | 1 | 296 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.57, 1.73] |
Comparison 113. SMS vs. postcard reminder.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 113.1 Final response | 3 | 9947 | Odds Ratio (M‐H, Random, 95% CI) | 1.49 [1.23, 1.81] |
Comparison 114. Electronic vs. mixed‐mode reminder (email and postal).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 114.1 First Response | 2 | 3999 | Odds Ratio (M‐H, Random, 95% CI) | 1.40 [0.76, 2.59] |
| 114.2 Final Response | 3 | 7159 | Odds Ratio (M‐H, Random, 95% CI) | 1.96 [0.89, 4.31] |
114.1. Analysis.
Comparison 114: Electronic vs. mixed‐mode reminder (email and postal), Outcome 1: First Response
Comparison 115. Electronic first vs. mixed‐mode first (mixed‐mode FU).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 115.1 First Response | 1 | 734 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [1.03, 2.01] |
| 115.2 Final Response | 1 | 734 | Odds Ratio (M‐H, Random, 95% CI) | 1.54 [1.15, 2.07] |
115.1. Analysis.
Comparison 115: Electronic first vs. mixed‐mode first (mixed‐mode FU), Outcome 1: First Response
Comparison 116. Push‐to‐web vs. choice.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 116.2 Final Response | 4 | 26482 | Odds Ratio (M‐H, Random, 95% CI) | 1.09 [0.99, 1.20] |
Comparison 117. Push‐to‐web (web, web/paper reminder) vs. mail only.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 117.2 Final Response | 1 | 3508 | Odds Ratio (M‐H, Random, 95% CI) | 1.26 [1.10, 1.45] |
Comparison 118. Mail push (mail, mail/web reminder) vs. mail only.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 118.2 Final Response | 1 | 3508 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.84, 1.10] |
Comparison 119. Push‐to‐web with email augmentation vs. no email augmentation.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 119.1 Final response | 1 | 2982 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [0.98, 1.31] |
Comparison 120. SMS reminder with URL vs. without.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 120.1 First Response | 1 | 178 | Odds Ratio (M‐H, Random, 95% CI) | 0.70 [0.30, 1.61] |
| 120.2 Final Response | 1 | 178 | Odds Ratio (M‐H, Fixed, 95% CI) | 1.00 [0.55, 1.82] |
120.1. Analysis.
Comparison 120: SMS reminder with URL vs. without, Outcome 1: First Response
Comparison 121. Electronic prompt vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 121.1 Final Response | 1 | 125 | Odds Ratio (M‐H, Random, 95% CI) | 1.27 [0.47, 3.48] |
Comparison 122. Sensitive questions vs. no/fewer/less sensitive questions asked.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 122.1 First response | 5 | 11292 | Odds Ratio (M‐H, Random, 95% CI) | 0.98 [0.90, 1.07] |
| 122.2 Final response | 10 | 21393 | Odds Ratio (M‐H, Random, 95% CI) | 0.94 [0.88, 1.00] |
122.1. Analysis.
Comparison 122: Sensitive questions vs. no/fewer/less sensitive questions asked, Outcome 1: First response
Comparison 123. More relevant questions first vs. last.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 123.1 First response | 1 | 5817 | Odds Ratio (M‐H, Random, 95% CI) | 1.28 [1.15, 1.42] |
| 123.2 Final response | 1 | 5817 | Odds Ratio (M‐H, Random, 95% CI) | 1.23 [1.10, 1.37] |
123.1. Analysis.
Comparison 123: More relevant questions first vs. last, Outcome 1: First response
Comparison 124. Most general questions first vs. last.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 124.1 Final response | 3 | 11435 | Odds Ratio (M‐H, Random, 95% CI) | 0.95 [0.83, 1.09] |
Comparison 125. Demographic items first vs. last.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 125.1 First response | 2 | 1040 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.83, 1.36] |
| 125.2 Final response | 5 | 10565 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.90, 1.16] |
125.1. Analysis.
Comparison 125: Demographic items first vs. last, Outcome 1: First response
Comparison 126. Easier questions first vs. last.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 126.1 First response | 1 | 240 | Odds Ratio (M‐H, Random, 95% CI) | 1.80 [0.91, 3.56] |
| 126.2 Final response | 2 | 3182 | Odds Ratio (M‐H, Random, 95% CI) | 1.61 [1.14, 2.26] |
126.1. Analysis.
Comparison 126: Easier questions first vs. last, Outcome 1: First response
Comparison 127. User friendly vs. standard questionnaire.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 127.1 First response | 1 | 3540 | Odds Ratio (M‐H, Random, 95% CI) | 1.46 [1.21, 1.75] |
| 127.2 Final response | 2 | 4087 | Odds Ratio (M‐H, Random, 95% CI) | 1.47 [1.25, 1.73] |
127.1. Analysis.
Comparison 127: User friendly vs. standard questionnaire, Outcome 1: First response
Comparison 128. More interesting vs. less or high salient topic vs. low.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 128.1 First response | 2 | 2151 | Odds Ratio (M‐H, Random, 95% CI) | 2.44 [1.99, 3.01] |
| 128.2 Final response | 4 | 6491 | Odds Ratio (M‐H, Random, 95% CI) | 1.73 [1.12, 2.66] |
| 128.3 e ‐ Submission | 1 | 2176 | Odds Ratio (M‐H, Random, 95% CI) | 1.85 [1.52, 2.26] |
128.1. Analysis.
Comparison 128: More interesting vs. less or high salient topic vs. low, Outcome 1: First response
Comparison 129. Open‐ended vs. closed questions.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 129.1 First response | 1 | 372 | Odds Ratio (M‐H, Random, 95% CI) | 0.38 [0.25, 0.59] |
| 129.2 Final response | 4 | 3092 | Odds Ratio (M‐H, Random, 95% CI) | 0.43 [0.19, 0.98] |
129.1. Analysis.
Comparison 129: Open‐ended vs. closed questions, Outcome 1: First response
Comparison 130. Open‐ended items first vs. other items first.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 130.1 First response | 1 | 300 | Odds Ratio (M‐H, Random, 95% CI) | 0.89 [0.55, 1.44] |
| 130.2 Final response | 1 | 300 | Odds Ratio (M‐H, Random, 95% CI) | 1.26 [0.73, 2.19] |
130.1. Analysis.
Comparison 130: Open‐ended items first vs. other items first, Outcome 1: First response
Comparison 131. Closed‐ended items first vs. other items first.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 131.1 First response | 1 | 300 | Odds Ratio (M‐H, Random, 95% CI) | 1.15 [0.71, 1.86] |
| 131.2 Final response | 1 | 300 | Odds Ratio (M‐H, Random, 95% CI) | 0.93 [0.54, 1.59] |
131.1. Analysis.
Comparison 131: Closed‐ended items first vs. other items first, Outcome 1: First response
Comparison 132. 'Don't know' boxes included vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 132.1 Final response | 1 | 1360 | Odds Ratio (M‐H, Random, 95% CI) | 1.03 [0.82, 1.29] |
Comparison 133. Circle answer vs. tick box format.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 133.1 Final response | 2 | 1125 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.74, 1.26] |
Comparison 134. Response options listed in increasing vs. decreasing order.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 134.1 Final response | 1 | 6783 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.94, 1.18] |
Comparison 135. High vs. medium frequency response alternatives.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 135.1 Final response | 2 | 3882 | Odds Ratio (M‐H, Random, 95% CI) | 1.40 [0.58, 3.38] |
Comparison 136. 5‐step vs. 10‐step response scale.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 136.1 Final response | 1 | 654 | Odds Ratio (M‐H, Random, 95% CI) | 0.78 [0.52, 1.19] |
Comparison 137. Individual item vs. stem & leaf format.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 137.1 Final response | 1 | 1500 | Odds Ratio (M‐H, Random, 95% CI) | 0.88 [0.70, 1.10] |
Comparison 138. Horizontal vs. vertical orientation of response options.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 138.1 Final response | 1 | 400 | Odds Ratio (M‐H, Random, 95% CI) | 3.12 [1.63, 5.96] |
Comparison 139. Conventional vs. randomised response technique.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 139.1 First response | 2 | 5830 | Odds Ratio (M‐H, Random, 95% CI) | 1.89 [1.69, 2.11] |
| 139.2 Final response | 4 | 7345 | Odds Ratio (M‐H, Random, 95% CI) | 1.52 [0.85, 2.72] |
139.1. Analysis.
Comparison 139: Conventional vs. randomised response technique, Outcome 1: First response
Comparison 140. Factual questions only vs. factual and attitudinal questions.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 140.1 Final response | 1 | 1280 | Odds Ratio (M‐H, Random, 95% CI) | 1.34 [1.01, 1.77] |
Comparison 141. Multi‐option vs. standard consent form.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 141.1 Final response | 1 | 200 | Odds Ratio (M‐H, Random, 95% CI) | 0.91 [0.49, 1.68] |
Comparison 142. Questions ordered by time period vs. other order.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 142.1 Final response | 1 | 259 | Odds Ratio (M‐H, Random, 95% CI) | 1.48 [0.84, 2.59] |
Comparison 143. Clinical outcome questions first vs. last.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 143.1 First Response | 2 | 226 | Odds Ratio (M‐H, Random, 95% CI) | 2.62 [0.81, 8.50] |
| 143.2 Final Response | 2 | 226 | Odds Ratio (M‐H, Random, 95% CI) | 2.05 [0.99, 4.25] |
143.1. Analysis.
Comparison 143: Clinical outcome questions first vs. last, Outcome 1: First Response
Comparison 144. University sponsor/source vs. other.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 144.1 First response | 4 | 5241 | Odds Ratio (M‐H, Random, 95% CI) | 1.35 [0.88, 2.08] |
| 144.2 Final response | 14 | 21628 | Odds Ratio (M‐H, Random, 95% CI) | 1.32 [1.13, 1.54] |
| 144.3 e ‐ Login | 2 | 3845 | Odds Ratio (M‐H, Random, 95% CI) | 0.80 [0.67, 0.96] |
| 144.4 e ‐ Submission | 2 | 3845 | Odds Ratio (M‐H, Random, 95% CI) | 0.84 [0.69, 1.01] |
144.1. Analysis.
Comparison 144: University sponsor/source vs. other, Outcome 1: First response
144.3. Analysis.
Comparison 144: University sponsor/source vs. other, Outcome 3: e ‐ Login
Comparison 145. Higher university sponsorship vs. lower.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 145.1 e ‐ Submission | 2 | 658 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.63, 1.45] |
Comparison 146. University printed envelope vs. plain.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 146.1 First response | 1 | 500 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.77, 1.57] |
| 146.2 Final response | 1 | 500 | Odds Ratio (M‐H, Random, 95% CI) | 0.88 [0.61, 1.28] |
146.1. Analysis.
Comparison 146: University printed envelope vs. plain, Outcome 1: First response
Comparison 147. Sent or signed by more vs. less senior/well‐known person.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 147.1 First response | 4 | 1526 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.85, 1.31] |
| 147.2 Final response | 11 | 5686 | Odds Ratio (M‐H, Random, 95% CI) | 1.05 [0.90, 1.23] |
| 147.3 e ‐ Login | 1 | 17346 | Odds Ratio (M‐H, Random, 95% CI) | 0.98 [0.91, 1.06] |
| 147.4 e ‐ Submission | 6 | 28162 | Odds Ratio (M‐H, Random, 95% CI) | 1.09 [0.96, 1.25] |
147.1. Analysis.
Comparison 147: Sent or signed by more vs. less senior/well‐known person, Outcome 1: First response
147.3. Analysis.
Comparison 147: Sent or signed by more vs. less senior/well‐known person, Outcome 3: e ‐ Login
Comparison 148. Pre‐contact by medical researcher vs. non medical researcher.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 148.1 Final response | 2 | 924 | Odds Ratio (M‐H, Random, 95% CI) | 1.01 [0.55, 1.86] |
Comparison 149. Q'aire sent by GP vs. by research group.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 149.1 First response | 1 | 409 | Odds Ratio (M‐H, Random, 95% CI) | 1.49 [1.00, 2.24] |
| 149.2 Final response | 2 | 1106 | Odds Ratio (M‐H, Random, 95% CI) | 1.52 [0.73, 3.15] |
149.1. Analysis.
Comparison 149: Q'aire sent by GP vs. by research group, Outcome 1: First response
Comparison 150. Male vs. female investigator or male vs. female signature.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 150.1 First response | 1 | 204 | Odds Ratio (M‐H, Random, 95% CI) | 1.42 [0.76, 2.64] |
| 150.2 Final response | 2 | 3146 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.72, 1.58] |
| 150.3 e ‐ Submission | 2 | 720 | Odds Ratio (M‐H, Random, 95% CI) | 0.55 [0.38, 0.80] |
150.1. Analysis.
Comparison 150: Male vs. female investigator or male vs. female signature, Outcome 1: First response
Comparison 151. Assurance of confidentiality vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 151.1 Final response | 1 | 25000 | Odds Ratio (M‐H, Random, 95% CI) | 1.33 [1.24, 1.42] |
Comparison 152. Included statement that others had responded vs. no statement.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 152.1 First response | 1 | 468 | Odds Ratio (M‐H, Random, 95% CI) | 1.12 [0.76, 1.65] |
| 152.2 Final response | 1 | 468 | Odds Ratio (M‐H, Random, 95% CI) | 1.12 [0.76, 1.65] |
| 152.3 e ‐ Login | 1 | 8586 | Odds Ratio (M‐H, Random, 95% CI) | 1.41 [1.28, 1.56] |
| 152.4 e ‐ Submission | 3 | 23777 | Odds Ratio (M‐H, Random, 95% CI) | 1.14 [0.83, 1.56] |
152.1. Analysis.
Comparison 152: Included statement that others had responded vs. no statement, Outcome 1: First response
152.3. Analysis.
Comparison 152: Included statement that others had responded vs. no statement, Outcome 3: e ‐ Login
Comparison 153. Choice to opt‐out from study vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 153.1 First response | 1 | 515 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.77, 1.56] |
| 153.2 Final response | 5 | 5544 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.74, 1.25] |
153.1. Analysis.
Comparison 153: Choice to opt‐out from study vs. none, Outcome 1: First response
Comparison 154. Instructions given vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 154.1 Final response | 1 | 2000 | Odds Ratio (M‐H, Random, 95% CI) | 0.89 [0.74, 1.06] |
Comparison 155. Response deadline given vs. no deadline.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 155.1 First response | 3 | 2575 | Odds Ratio (M‐H, Random, 95% CI) | 1.25 [0.93, 1.69] |
| 155.2 Final response | 6 | 5661 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.84, 1.19] |
| 155.3 e ‐ Login | 1 | 8586 | Odds Ratio (M‐H, Random, 95% CI) | 1.20 [1.07, 1.35] |
| 155.4 e ‐ Submission | 1 | 8586 | Odds Ratio (M‐H, Random, 95% CI) | 1.18 [1.03, 1.34] |
155.1. Analysis.
Comparison 155: Response deadline given vs. no deadline, Outcome 1: First response
155.3. Analysis.
Comparison 155: Response deadline given vs. no deadline, Outcome 3: e ‐ Login
Comparison 156. Mention of obligation to respond vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 156.1 First response | 3 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 1.61 [1.16, 2.22] |
| 156.2 Final response | 3 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 1.61 [1.16, 2.22] |
156.1. Analysis.
Comparison 156: Mention of obligation to respond vs. none, Outcome 1: First response
Comparison 157. Request for telephone number vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 157.1 First response | 1 | 702 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.65, 1.54] |
| 157.2 Final response | 1 | 702 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.65, 1.54] |
157.1. Analysis.
Comparison 157: Request for telephone number vs. none, Outcome 1: First response
Comparison 158. Respond on questionnaire vs. on separate form.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 158.1 First response | 1 | 200 | Odds Ratio (M‐H, Random, 95% CI) | 1.11 [0.59, 2.07] |
| 158.2 Final response | 1 | 200 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [0.57, 2.27] |
158.1. Analysis.
Comparison 158: Respond on questionnaire vs. on separate form, Outcome 1: First response
Comparison 159. Mention of follow‐up contact vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 159.1 First response | 5 | 4553 | Odds Ratio (M‐H, Random, 95% CI) | 1.16 [1.02, 1.33] |
| 159.2 Final response | 7 | 7053 | Odds Ratio (M‐H, Random, 95% CI) | 1.02 [0.91, 1.15] |
159.1. Analysis.
Comparison 159: Mention of follow‐up contact vs. none, Outcome 1: First response
Comparison 160. Explanation for non‐participation requested vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 160.1 First response | 1 | 667 | Odds Ratio (M‐H, Random, 95% CI) | 0.97 [0.71, 1.32] |
| 160.2 Final response | 2 | 1907 | Odds Ratio (M‐H, Random, 95% CI) | 1.14 [0.83, 1.57] |
160.1. Analysis.
Comparison 160: Explanation for non‐participation requested vs. not, Outcome 1: First response
Comparison 161. Time estimate for completion given vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 161.1 First response | 1 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.76, 1.58] |
| 161.2 Final response | 1 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 1.10 [0.76, 1.58] |
161.1. Analysis.
Comparison 161: Time estimate for completion given vs. not, Outcome 1: First response
Comparison 162. Detailed vs. brief cover letter.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 162.2 Final response | 1 | 500 | Odds Ratio (M‐H, Random, 95% CI) | 1.08 [0.74, 1.58] |
| 162.3 e‐Submission | 1 | 1250 | Odds Ratio (M‐H, Random, 95% CI) | 3.26 [1.79, 5.94] |
Comparison 163. Appeal vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 163.1 Final response | 2 | 1251 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.79, 1.42] |
| 163.2 e ‐ Login | 3 | 4351 | Odds Ratio (M‐H, Random, 95% CI) | 0.94 [0.76, 1.16] |
| 163.3 e ‐ Submission | 4 | 5915 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.79, 1.47] |
163.2. Analysis.
Comparison 163: Appeal vs. none, Outcome 2: e ‐ Login
Comparison 164. Note requesting not to remove ID code vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 164.1 First response | 1 | 100 | Odds Ratio (M‐H, Random, 95% CI) | 0.37 [0.14, 0.96] |
| 164.2 Final response | 1 | 100 | Odds Ratio (M‐H, Random, 95% CI) | 0.37 [0.14, 0.96] |
164.1. Analysis.
Comparison 164: Note requesting not to remove ID code vs. none, Outcome 1: First response
Comparison 165. Request for participant signature vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 165.1 Final response | 1 | 201 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.65, 2.18] |
Comparison 166. Questionnaire endorsed vs. not endorsed.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 166.1 First response | 1 | 395 | Odds Ratio (M‐H, Random, 95% CI) | 0.33 [0.15, 0.74] |
| 166.2 Final response | 1 | 395 | Odds Ratio (M‐H, Random, 95% CI) | 0.63 [0.43, 0.94] |
166.1. Analysis.
Comparison 166: Questionnaire endorsed vs. not endorsed, Outcome 1: First response
Comparison 167. Veiled threat in follow‐up letter vs. none.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 167.1 First response | 1 | 671 | Odds Ratio (M‐H, Random, 95% CI) | 2.09 [1.49, 2.93] |
| 167.2 Final response | 1 | 671 | Odds Ratio (M‐H, Random, 95% CI) | 2.09 [1.49, 2.93] |
167.1. Analysis.
Comparison 167: Veiled threat in follow‐up letter vs. none, Outcome 1: First response
Comparison 168. Appeal stresses benefit to sponsor vs. other.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 168.1 First response | 3 | 2376 | Odds Ratio (M‐H, Random, 95% CI) | 1.20 [0.88, 1.63] |
| 168.2 Final response | 8 | 10908 | Odds Ratio (M‐H, Random, 95% CI) | 0.99 [0.86, 1.13] |
168.1. Analysis.
Comparison 168: Appeal stresses benefit to sponsor vs. other, Outcome 1: First response
Comparison 169. Appeal stresses benefit to respondent vs. other.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 169.1 First response | 1 | 1500 | Odds Ratio (M‐H, Random, 95% CI) | 0.97 [0.78, 1.21] |
| 169.2 Final response | 10 | 15159 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.85, 1.17] |
169.1. Analysis.
Comparison 169: Appeal stresses benefit to respondent vs. other, Outcome 1: First response
Comparison 170. Appeal stresses benefit to society vs. other.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 170.1 First response | 3 | 3906 | Odds Ratio (M‐H, Random, 95% CI) | 0.98 [0.82, 1.17] |
| 170.2 Final response | 14 | 36107 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.95, 1.20] |
| 170.3 e‐Submission | 3 | 3536 | Odds Ratio (M‐H, Random, 95% CI) | 1.35 [0.95, 1.91] |
170.1. Analysis.
Comparison 170: Appeal stresses benefit to society vs. other, Outcome 1: First response
Comparison 171. Anonymous vs. not anonymous.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 171.1 Final response | 2 | 2070 | Odds Ratio (M‐H, Random, 95% CI) | 0.96 [0.66, 1.39] |
Comparison 172. Cover letter highlights salience vs. standard cover letter.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 172.1 First response | 2 | 27119 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.75, 1.50] |
| 172.2 Final response | 2 | 27119 | Odds Ratio (M‐H, Random, 95% CI) | 1.06 [0.75, 1.50] |
172.1. Analysis.
Comparison 172: Cover letter highlights salience vs. standard cover letter, Outcome 1: First response
Comparison 173. Salient cover letter message on 1st mailing vs. follow‐up.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 173.1 First response | 1 | 2180 | Odds Ratio (M‐H, Random, 95% CI) | 2.49 [1.82, 3.40] |
| 173.3 Final response | 1 | 2180 | Odds Ratio (M‐H, Random, 95% CI) | 2.49 [1.82, 3.40] |
173.1. Analysis.
Comparison 173: Salient cover letter message on 1st mailing vs. follow‐up, Outcome 1: First response
Comparison 174. Letter states responses being monitored vs. standard letter.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 174.1 First response | 2 | 5202 | Odds Ratio (M‐H, Random, 95% CI) | 1.14 [1.01, 1.29] |
| 174.2 Final response | 1 | 4447 | Odds Ratio (M‐H, Random, 95% CI) | 1.15 [1.01, 1.31] |
174.1. Analysis.
Comparison 174: Letter states responses being monitored vs. standard letter, Outcome 1: First response
Comparison 175. Letter emphasises health promotion vs. harm prevention.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 175.1 First response | 1 | 1418 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.83, 1.72] |
| 175.2 Final response | 1 | 1418 | Odds Ratio (M‐H, Random, 95% CI) | 1.19 [0.83, 1.72] |
175.1. Analysis.
Comparison 175: Letter emphasises health promotion vs. harm prevention, Outcome 1: First response
Comparison 176. Letter emphasises harm prevention vs. neutral message.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 176.1 First response | 1 | 1410 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [0.98, 2.12] |
| 176.2 Final response | 1 | 1410 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [0.98, 2.12] |
176.1. Analysis.
Comparison 176: Letter emphasises harm prevention vs. neutral message, Outcome 1: First response
Comparison 177. Behaviour change letter vs. standard.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 177.1 First response | 1 | 1192 | Odds Ratio (M‐H, Random, 95% CI) | 1.39 [1.08, 1.77] |
Comparison 178. Participants told completion time 10 mins vs. 30 mins.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 178.1 e ‐ Login | 1 | 2358 | Odds Ratio (M‐H, Random, 95% CI) | 0.55 [0.46, 0.66] |
| 178.2 e ‐ Submission | 1 | 2358 | Odds Ratio (M‐H, Random, 95% CI) | 1.25 [0.96, 1.64] |
178.1. Analysis.
Comparison 178: Participants told completion time 10 mins vs. 30 mins, Outcome 1: e ‐ Login
Comparison 179. Culturally sensitive letter vs. generic.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 179.1 Final response | 1 | 1316 | Odds Ratio (M‐H, Random, 95% CI) | 1.00 [0.74, 1.34] |
Comparison 180. Ethnically unidentifiable/white vs. other name.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 180.1 First response | 1 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 1.12 [0.79, 1.59] |
| 180.2 Final response | 5 | 5959 | Odds Ratio (M‐H, Random, 95% CI) | 1.07 [0.90, 1.27] |
180.1. Analysis.
Comparison 180: Ethnically unidentifiable/white vs. other name, Outcome 1: First response
Comparison 181. Brown vs. white envelope.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 181.1 First response | 3 | 5423 | Odds Ratio (M‐H, Random, 95% CI) | 1.44 [0.73, 2.83] |
| 181.2 Final response | 6 | 9756 | Odds Ratio (M‐H, Random, 95% CI) | 1.25 [0.86, 1.80] |
181.1. Analysis.
Comparison 181: Brown vs. white envelope, Outcome 1: First response
Comparison 182. Check categories or specify numbers vs. check categories only.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 182.1 First response | 1 | 740 | Odds Ratio (M‐H, Random, 95% CI) | 0.80 [0.60, 1.06] |
| 182.2 Final response | 1 | 740 | Odds Ratio (M‐H, Random, 95% CI) | 0.80 [0.60, 1.06] |
182.1. Analysis.
Comparison 182: Check categories or specify numbers vs. check categories only, Outcome 1: First response
182.2. Analysis.
Comparison 182: Check categories or specify numbers vs. check categories only, Outcome 2: Final response
Comparison 183. Shorter vs. longer questionnaire.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 183.1 First response | 30 | 1347691 | Odds Ratio (M‐H, Random, 95% CI) | 1.13 [1.06, 1.21] |
| 183.2 Final response | 72 | 84954 | Odds Ratio (M‐H, Random, 95% CI) | 1.58 [1.40, 1.78] |
| 183.3 e ‐ Login | 2 | 3456 | Odds Ratio (M‐H, Random, 95% CI) | 1.79 [1.55, 2.07] |
| 183.4 e ‐ Submission | 5 | 12325 | Odds Ratio (M‐H, Random, 95% CI) | 1.51 [1.06, 2.16] |
183.1. Analysis.
Comparison 183: Shorter vs. longer questionnaire, Outcome 1: First response
183.3. Analysis.
Comparison 183: Shorter vs. longer questionnaire, Outcome 3: e ‐ Login
Comparison 184. Double postcard vs. one page.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 184.1 First response | 1 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 0.66 [0.48, 0.91] |
| 184.2 Final response | 1 | 600 | Odds Ratio (M‐H, Random, 95% CI) | 0.47 [0.34, 0.66] |
184.1. Analysis.
Comparison 184: Double postcard vs. one page, Outcome 1: First response
Comparison 185. Questionnaire sent with supplement vs. alone.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 185.1 Final response | 1 | 1795 | Odds Ratio (M‐H, Random, 95% CI) | 0.86 [0.70, 1.07] |
Comparison 186. Extra questionnaire for relatives included vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 186.1 Final response | 2 | 4943 | Odds Ratio (M‐H, Random, 95% CI) | 0.67 [0.60, 0.76] |
Comparison 187. Consent form included vs. not.
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
|---|---|---|---|---|
| 187.1 First response | 1 | 414 | Odds Ratio (M‐H, Random, 95% CI) | 1.21 [0.81, 1.81] |
| 187.2 Final response | 1 | 414 | Odds Ratio (M‐H, Random, 95% CI) | 1.32 [0.89, 1.95] |
187.1. Analysis.
Comparison 187: Consent form included vs. not, Outcome 1: First response
Characteristics of studies
Characteristics of included studies [ordered by study ID]
Aadahl 2003.
| Study characteristics | ||
| Methods | Random allocation: random numbers using SAS | |
| Data | Random sample of 2543 men and women from the Danish Civil Registration System (Copenhagen County, Denmark) | |
| Comparisons | 1. Lottery (25 euro voucher) 2. Control |
|
| Outcomes | Response at 4 weeks | |
| Topic | Health: Self‐rated health, physical activity, and sociodemographics | |
| Mode of Administration | Postal | |
| Notes | Mean age: 40.5 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Abdulaziz 2015.
| Study characteristics | ||
| Methods | Randomly allocated by computer‐generated random numbers | |
| Data | 178 emergency physicians, 178 geriatricians and 178 family physicians | |
| Comparisons | Incentive $10 coffee card with questionnaire vs no incentive | |
| Outcomes | Response after 3‐weekly reminders plus a final reminder sent by express courier | |
| Topic | Health services (treatment of elderly patients with minor injuries, i.e. lacerations, contusions, nonoperative fractures, etc.) | |
| Mode of Administration | Postal | |
| Notes | 13 questions; 5 sections; 2 pages; single‐sided. The survey package consisted of a cover letter, a questionnaire, and a prepaid business reply mail envelope. Personalised prenotification (1 wk prior) and cover letters were used (all hand‐signed, plus physician name, area of expertise and affiliation were printed on the cover letter). | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Respondents were blind to the intervention and so would not be aware that others may have received a different or no incentive. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Of the 534 physicians surveyed, 27 were not reachable because they had moved and 42 were ineligible as they were no longer practising or were not seeing elderly patients. Of the 465 eligible physicians, 265 completed and returned the survey (including the 12 of the 16 physicians from the local pilot survey) resulting in an overall response rate of 57%. |
| Selective reporting | Yes | The authors specified: "The primary outcome was the physician response rate", and no other outcomes were reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Adams 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Full‐time students (Brigham Young University, US) | |
| Comparisons | 1. 1‐page questionnaire 2. 3‐page questionnaire 3. 5‐page questionnaire | |
| Outcomes | Response at 3 months | |
| Topic | Non‐health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Agarwal 2016.
| Study characteristics | ||
| Methods | Computer‐generated (Excel) random sequence of numbers | |
| Data | Chairpersons of all academic Departments of Medicine in the United States | |
| Comparisons | Unconditional $5 coffee card ("for administrative assistants time") vs no incentive | |
| Outcomes | First mailing response, response after a follow‐up letter, and response after a follow‐up phone call | |
| Topic | Non‐health; how departments measure faculty productivity for the purpose of salary compensation | |
| Mode of Administration | Postal | |
| Notes | 8 questions (23 tabulated closed‐ended items); "short questionnaire focusing on factual questions" Initially, we notified potential participants via the listserv of Chairs of Internal Medicine about the upcoming survey. Then, we mailed participants a survey package including a personalised cover letter, the survey questionnaire, and a pre‐addressed stamped return envelope. Two weeks after the initial mailing, we sent non‐responders a follow‐up letter. Two weeks later, we attempted to contact non‐responders by phone. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Excel) random sequence of numbers |
| Allocation concealment? | Yes | Random allocation: Microsoft Excel to generate a random sequence of numbers |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | No | First response was not reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Akl 2005.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents and faculty of the University at Buffalo Internal Medicine Residency programme | |
| Comparisons | Electronic vs postal surveys | |
| Outcomes | Response at day 30 after 2 reminders (at days 10 and 20) | |
| Topic | Non‐health: academic issues | |
| Mode of Administration | Electronic | |
| Notes | 28 questions (residents) or 23 (faculty) addressing demographic data, academic issues and survey mailing method. Except demographic questions, all had seven‐point Likert scale answer formats. Participants also had the option of providing narrative comments. The website that hosted the e‐survey generated automatic reminder emails. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method not specified |
| Allocation concealment? | Unclear | Random allocation: method not specified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Akl 2011.
| Study characteristics | ||
| Methods | Computer‐generated (Excel) | |
| Data | Directors of Family Medicine and Internal Medicine residency programs in the US | |
| Comparisons | Mailing day (Friday vs. Monday) Response tracking (Yes vs. No) | |
| Outcomes | First response, response after a reminder at 5 weeks, response after a fax reminder at 9 weeks | |
| Topic | Health (training of residents in the implementation of clinical practice guidelines) | |
| Mode of Administration | Postal | |
| Notes | 2 single‐sided pages with 15 questions about the curriculum, the characteristics of the programme director and the characteristics of the residency programme Initial invitation April 2007. To maximise response, the investigators included: university sponsorship, personalised cover letter, coloured ink, stamped return envelope, first‐class mailing, follow‐up mail, including a questionnaire in the follow‐up mail, and a short user‐friendly questionnaire with factual questions. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Excel) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (Excel) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | No attrition/exclusion reported |
| Selective reporting | No | Only reported numbers responding by the time of the 2nd reminder by intervention group |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Albaum 1987.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of public employees credit group | |
| Comparisons | 1. University source; open code
2. Research firm source; open code
3. Credit union source; open code
4. University source; no code
5. Research firm source; no code
6. Credit union source; no code Mailed reminder notification and follow‐up |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Albaum 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Marketing managers of manufacturing firms (Denmark) | |
| Comparisons | 1. Pre‐contact by letter; brochure explaining the study in depth 2. Pre‐contact; no brochure 3. No pre‐contact; brochure 4. No pre‐contact; no brochure | |
| Outcomes | Response within 67 days | |
| Topic | Non‐health: business, employment, and finance | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Allen 2016.
| Study characteristics | ||
| Methods | Computer‐generated (a Perl script automatically randomised each participant to one of the versions of the survey. The only way to detect the presence of the Perl script on this page was to examine its source code) | |
| Data | A convenience sample of 498 adults recruited via face‐to‐face (e.g. flyers) and electronic (e.g. email messages and links on websites) methods. 60% were students. Most had access to broadband Internet. | |
| Comparisons | High uni sponsorship, mandatory questions vs low uni sponsorship, mandatory questions; high uni sponsorship, optional questions vs low uni sponsorship, optional questions | |
| Outcomes | Dropout ‐ whether or not the participant clicked the submit button at the end of the survey. Item non‐response ‐ the number of items (out of 78 and 65) that the participant provided a response to | |
| Topic | Internet piracy | |
| Mode of Administration | Electronic (web survey) | |
| Notes | 78‐item questionnaire with a 10‐page online survey No compensation was provided for participation; however, participants were offered the opportunity to enter a prize draw as a token of appreciation for their time. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Perl script (Wright, 1996) automatically randomised each participant to one of the versions of the survey. |
| Allocation concealment? | Yes | Computer‐generated (a Perl script automatically randomised each participant to one of the versions of the survey. The only way to detect the presence of the Perl script on this page was to examine its source code). |
| Blinding of participants and personnel | Yes | The information page that preceded each version of the survey described the research as investigating factors influencing Internet piracy and survey completion behaviours, but did not explicitly mention the experimental manipulation. Personnel not involved in the process |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | No mention of exclusions |
| Selective reporting | Yes | First response to survey was reported (no follow‐up) |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Allen 2016a.
| Study characteristics | ||
| Methods | Computer‐generated (a Perl script automatically randomised each participant to one of the versions of the survey. The only way to detect the presence of the Perl script on this page was to examine its source code) | |
| Data | A convenience sample of 159 adults was recruited via face‐to‐face (e.g. flyers) and electronic (e.g. email messages and links on websites) methods in mid‐2011. 70 percent were female. | |
| Comparisons | High uni sponsorship vs low uni sponsorship | |
| Outcomes | Dropout ‐ whether or not the participant clicked the submit button at the end of the survey. Item non‐response ‐ the number of items (out of 78 and 65) that the participant provided a response to | |
| Topic | Internet behaviour survey | |
| Mode of Administration | Electronic (web survey) | |
| Notes | 65‐item questionnaire, 7‐page online survey Participants were not offered any incentives or compensation for participation. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Perl script (Wright, 1996) automatically randomised each participant to one of the versions of the survey. |
| Allocation concealment? | Yes | Computer‐generated (a Perl script automatically randomised each participant to one of the versions of the survey. The only way to detect the presence of the Perl script on this page was to examine its source code). |
| Blinding of participants and personnel | Yes | The information page that preceded each version of the survey described the research as investigating factors influencing Internet piracy and survey completion behaviours, but did not explicitly mention the experimental manipulation. Personnel not involved in the process |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | No mention of exclusions |
| Selective reporting | Yes | First response to survey was reported (no follow‐up) |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Alutto 1970.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Members of a western New York State Chamber of Commerce | |
| Comparisons | 1. Questionnaire sent to work address 2. Questionnaire sent to home address | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards universities | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐inadequate |
Andreasen 1970.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | New York State lottery winners | |
| Comparisons | 1. Mimeographed salutation; follow‐up mimeographed
2. Mimeographed salutation; follow‐up handwritten
3. Hand‐typed salutation; follow‐up mimeographed
4. Hand‐typed salutation; follow‐up handwritten
5. Hand‐typed salutation using name of participant with handwritten postscript; follow‐up mimeographed
6. Hand‐typed salutation using name of participant with handwritten postscript; follow‐up handwritten Follow‐up letters sent after 3 weeks Follow‐up questionnaires sent after 4 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Antoun 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Members of the LISS panel (Longitudinal Internet studies for the Social Sciences) | |
| Comparisons | Smartphone vs computer | |
| Outcomes | Started questionnaire; completed questionnaire | |
| Topic | Topics ranging from health to politics | |
| Mode of Administration | Electronic | |
| Notes | 46 questions; 32 survey pages Survey invitations sent by email, normal LISS cash incentive provided for participation |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | No mention of blinding. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Participants who completed the Web questionnaire using a different device than they were assigned, perhaps because they failed to carefully read the instructions in their invitation letters or because they had a strong preference for one device over the other, were not included in the analysis. |
| Selective reporting | Yes | Responses after two periods were fully reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Arai 2016.
| Study characteristics | ||
| Methods | Computer (Excel)‐generated random numbers | |
| Data | People registered to vote in 123 municipalities in Japan in September 2012 | |
| Comparisons | Pen incentive (cheap vs. expensive; boxed vs. unboxed) | |
| Outcomes | Response period not specified | |
| Topic | Non‐health (whether levels of public goods and services had declined in rural communities that experienced municipal mergers in the recent past) | |
| Mode of Administration | Postal | |
| Notes | 18 questions plus several additional demographic questions, one piece of A3 paper, with questions printed on both sides of the paper) Pre‐notification postcard; one week later posted questionnaire by direct mail service with return envelope and pen (high price/low, boxed/unboxed) or no pen |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Computer (Excel)‐generated random numbers |
| Allocation concealment? | Yes | Computer (Excel)‐generated random numbers |
| Blinding of participants and personnel | Yes | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Of the 12,309, we were able to contact 11,914 voters, as there were approximately 400 voters who were unreachable. |
| Selective reporting | Yes | No follow‐up mailings were sent, so only one response was possible (final response) and this was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Arzheimer 1999.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A random sample of people listed on registration file, Hamburg, Germany | |
| Comparisons | 1. Phonecard worth 6 Deutsch marks included 2. No incentive | |
| Outcomes | Response in first wave of mailing | |
| Topic | Non‐health: voting behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Asch 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Subscribers to nursing who had previously indicated practice in critical care settings (US) | |
| Comparisons | 1. Questionnaire sent 3 times 2. Questionnaire sent with postcard. If postcard was returned, participant received no follow‐up mailings. | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | Author contacted: no further information on allocation concealment | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Asch 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Primary care physicians identified through the American Medical Association Physician Master File (US) | |
| Comparisons | 1. $2 incentive sent with questionnaire 2. $5 incentive sent with questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | Author contacted: no further information on allocation concealment | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ashby 2011.
| Study characteristics | ||
| Methods | Randomly‐generated numbers used to allocate participants to intervention and control groups | |
| Data | Participants who were taking part in an RCT investigating the effect of a food elimination diet based on the enzyme‐linked immunosorbent assay (ELISA) test for food sensitivity for the prevention of migraine | |
| Comparisons | Electronic reminder (SMS/email/both) vs no reminder | |
| Outcomes | Response within 39 days | |
| Topic | Health (migraine) | |
| Mode of Administration | Postal | |
| Notes | A two‐page, double‐sided questionnaire, which contained the HIT‐6 (Version 1.1) (Headache Impact Test) and Migraine Disability Assessment Test. These are questionnaires used to measure the impact headaches have on a participant's life. A return date was located on the front page of all questionnaires sent out to participants. Participants in the intervention group were sent an ER (electronic reminder) in the form of an SMS, email message, or both. The SMS text message read "You should have a new diary and a questionnaire by now. The questionnaire is important so please send it back with your first diary asap. Thanks." The content of the email reminder was "Thank you for taking part in the Migraine study. This is an automatic reminder. You should have received your 4‐week questionnaire by today and your second diary. It is important that we receive your first diary and your 4‐week questionnaire back as soon as possible." |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Randomly‐generated numbers were used to list all participants by ID number. The first half of participants contained within this list (74 of 148) were allocated to the intervention group, whereas the remaining participants (74 of 148) were allocated to the control group. |
| Allocation concealment? | Yes | An independent data manager at the York Trials Unit was responsible for generating the allocation sequence and assigning participants into intervention and control groups. |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Participants excluded (n = 26/174). No email address or mobile telephone number was available. |
| Selective reporting | Yes | Response within 39 days was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ashing‐Giwa 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A sample of African‐American and white American breast cancer patients diagnosed in 1989 and 1990 | |
| Comparisons | 1. $5 gift certificate sent with questionnaire 2. Promise of $5 gift certificate on response | |
| Outcomes | Response period not specified | |
| Topic | Health: quality of life in long‐term breast cancer survivors | |
| Mode of Administration | Postal | |
| Notes | Mean age: 63.6 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Aveyard 2001.
| Study characteristics | ||
| Methods | Random allocation: participants randomly sorted and then the first 150 given intervention | |
| Data | 300 smokers selected randomly from 2 general practices in the United Kingdom | |
| Comparisons | 1. Pencil and eraser sent with questionnaire 2. No pencil or eraser sent with questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Health: recruitment for a smoking cessation programme | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bachman 1987.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Taxpayers (Missouri) | |
| Comparisons | 1. Student sponsor; social appeal 2. Student sponsor; help the sponsor appeal 3. Business sponsor; social appeal 4. Business sponsor; help the sponsor appeal 5. Commercial sponsor; social appeal 6. Commercial sponsor; help the sponsor appeal | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: public attitude towards Missouri Department of Revenue | |
| Mode of Administration | Postal | |
| Notes | Author contacted: no further information on allocation concealment | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bakan 2014.
| Study characteristics | ||
| Methods | Unspecified | |
| Data | Prostate cancer survivors, 2 to 8 years post‐prostate cancer diagnosis | |
| Comparisons | Unconditional incentive ($5 food gift card), priority mail, incentive and priority mail or control | |
| Outcomes | Surveys returned within 48 days of the first survey mailing were considered responders to the first mailing, while surveys returned between 49 and 100 days after the first survey mailing were considered responders to the second mailing. | |
| Topic | Health outcomes in prostate cancer survivors (participant's demographic and medical characteristics, cancer treatment history, health, and quality of life) | |
| Mode of Administration | Postal | |
| Notes | 10‐page questionnaire Survey package included 1st class pre‐notification letter. Mailings to all groups were addressed to the intended participant using a typed label, and included a personalised cover letter, the 10‐page survey, a resource sheet, and a postage‐paid, pre‐addressed return envelope. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation ‐ method unspecified |
| Allocation concealment? | Unclear | Random allocation ‐ method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Eight survivors declined study participation after the introductory letter, but prior to the first mailing, and were excluded from analyses. Nine surveys were returned as undeliverable, and 7 were returned with notification of patient death, yielding an evaluable sample of 976. |
| Selective reporting | Yes | Two mailings were conducted and both were reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Barker 1996.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | Individuals randomly selected from electoral registers (Solihull, UK) | |
| Comparisons | 1. Question on sexual health included
2. Question on sexual health not included Reminder letter and questionnaire sent to non‐responders 3 weeks after initial mailing |
|
| Outcomes | Response period not specified | |
| Topic | Health: sexual health | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Barra 2016.
| Study characteristics | ||
| Methods | Each participant was assigned an internal identification number. A list of the identification numbers were sent to a statistician external to the project who generated the control and intervention groups by random allocation. | |
| Data | Stroke patients discharged from the Stroke Unit of Akerhus University Hospital | |
| Comparisons | Pre‐contact by telephone vs. no pre‐contact | |
| Outcomes | Response at 45 days and response at 365 days | |
| Topic | Health services; patient's levels of contentment with, and benefit from, consumption of health services over the year following hospitalisation | |
| Mode of Administration | Postal | |
| Notes | Two questionnaires in the envelope (16 (patient) and 8 (caregiver) pages). Survey package included an envelope with handwritten address in the name of the patient and, where available, the name of the spouse. The envelope contained two questionnaires and a cover letter explaining the purpose of the study, ensuring confidentiality, and equipped with contact information for any queries. The cover letter was hand‐signed. The two questionnaires were made out for the patient and for a caregiver. 2 SAEs for each questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants could not be blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | During the intervention period, it was discovered through the ongoing data collection that 6 patients (3 in each arm) suffered from known dementia, and these were excluded from the study. 10 patients (7 in the intervention group and 3 in the control group) died before 12 months had passed from discharge from hospital; these were also excluded. Furthermore, one patient in the intervention group was discovered to have been misdiagnosed with stroke, and one patient in the control group was discovered to be a very frail nursing home patient, who had been mis‐assessed as eligible for inclusion. 105 subjects in the intervention groupand 112 controls remained. |
| Selective reporting | Yes | Primary and secondary outcomes reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Basnov 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Women referred for mammography (up to retirement age, 67), Denmark | |
| Comparisons | Electronic vs. postal | |
| Outcomes | Response period not specified | |
| Topic | Health (Short Form Health Survey and The Hospital Anxiety and Depression Scale) | |
| Mode of Administration | Electronic and postal | |
| Notes | Questionnaires: 17 pages and 119 items. The letter to women randomised to answer the internet version of the questionnaire included a guideline on how to answer the Web‐based questionnaire, whereas those allocated to the pen‐and‐paper version were asked to fill in and return the questionnaire in a prepaid envelope. The layout of the pen‐and‐paper version of SF‐36 was in accordance with the Danish manual of SF‐36 (Short Form‐36), and the layout of the internet version was as close to the paper version as possible. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not reported. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | No | Only one response proportion was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bauer 2004.
| Study characteristics | ||
| Methods | Random allocation | |
| Data | People who participated both in the COMMunity Intervention Trial for smoking cessation (COMMIT) as well as the follow‐up study | |
| Comparisons | 1. US$ 2 Cheque 2. US$ 10 Cheque 3. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: smoking cessation | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly 48‐57 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bech 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Individuals aged 50‐75 years drawn from the Central National Register of the Danish population | |
| Comparisons | Web vs. postal | |
| Outcomes | Response period not specified | |
| Topic | Non‐health (mostly attitudinal questions about the design of nursing homes and associated facilities) | |
| Mode of Administration | Postal and electronic (web) | |
| Notes | 35 closed‐ended categorical questions; postal 16 pages Questionnaire and SAE, or letter with web‐link |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not mentioned. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | 100 individuals from the original random draw were used in a pilot test of the Web‐based survey. |
| Selective reporting | Yes | Final response reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Becker 2000a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | BSN alumni who graduated between 1989 and 1997 who had not returned an initial survey | |
| Comparisons | 1. Second questionnaire sent as follow‐up 2. Postcard follow‐up (no second questionnaire) | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: professional experience since graduation and perceptions of academic preparation | |
| Mode of Administration | Postal | |
| Notes | Additional data obtained from author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Becker 2000b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Alumni who graduated with a PhD or MSN between 1988 and 1997 who had not returned an initial survey | |
| Comparisons | 1. Second questionnaire sent as follow‐up 2. Postcard follow‐up (no second questionnaire) | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: professional experience since graduation and perceptions of academic preparation | |
| Mode of Administration | Postal | |
| Notes | Additional data obtained from author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Beebe 2005a.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees. Simple random sample | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2005b.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees. American‐Indian | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2005c.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2005d.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees. Somali | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2005e.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees. Latino | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2005f.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Medicaid enrollees. African‐American | |
| Comparisons | 1. US$ 2 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: racial and ethnic disparities in the use of health services and barriers to care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Beebe 2007.
| Study characteristics | ||
| Methods | Random allocation: using RANUNI function in SAS | |
| Data | Mayo clinic patients | |
| Comparisons | 1. Small booklet (6 1/8 X 8 1/4") 2. Large booklet (8 1/4 X 11") 3. Blue booklet 8. White booklet |
|
| Outcomes | Response period not specified | |
| Topic | Health: measure awareness and knowledge of privacy practices, and general opinions on privacy and health care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author; mean age: 57.6 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | No mention of blinding of personnel. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Two cases (one in the small/blue condition and one in the large/white condition) were excluded due to their being deceased or physically impaired, leaving roughly 500 cases assigned to each of the four conditions. |
| Selective reporting | Yes | Responses after all mailings were reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Beebe 2007a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 500 primary care physicians and specialists (allergists, cardiologists, gastroenterologists, haematologists, nephrologists, pulmonologists, and rheumatologists) from the 12 different divisions within the Mayo Clinic Dept Of Medicine | |
| Comparisons | Mailed survey first, then web survey follow‐up to non‐respondents vs. web survey first, then mailed survey follow‐up to non‐respondents | |
| Outcomes | First response and response after one reminder | |
| Topic | Health services: designed to elicit opinions of Dept of Medicine members about the Mayo Clinic Electronic Medical Record (EMR) | |
| Mode of Administration | Postal and electronic | |
| Notes | The instrument contained approximately 20 Likert‐style items measuring general comfort using computers and various aspects of the Electronic Medical Record, including: level of use, adequacy of training, comfort level, helpfulness, satisfaction, and preference over paper medical records. The web survey design and layout was made to be as comparable to the paper version as possible. The mailed survey was sent to physician's offices via inter‐office mail and the web survey was distributed by an email message to the physician with an embedded link to the web survey. The reminder was sent in the medium corresponding to the initial mailing (electronically or via inter‐office mail). For the web condition, the reminder did not contain an embedded link to the web survey for comparability to its mailed counterpart. For those not responding to the initial mailing, the medium in which the follow‐up survey was sent was switched. Specifically, those non‐respondents in the web first condition received their follow‐up survey via mail; those in the mail first condition received the follow‐up via email. One week before the close of data collection, another email message was sent from the Dept of Medicine chair to all Dept of Medicine members encouraging them to respond to the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not reported. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | 11 cases were removed from the sample due to ineligibility or duplicate listing. |
| Selective reporting | Yes | First response and response after one reminder were both reported. |
| Other sources of bias | Yes | Supporting analysis and consideration of non‐response bias |
Beebe 2010.
| Study characteristics | ||
| Methods | Computer‐generated (subjects were randomly assigned to four conditions using the RANUNI function in SAS v. 9.1. software according to a 2√ó 2 factorial design) | |
| Data | Residents of Olmsted County, Minnesota, aged 25‐65 years old registered in the Rochester Epidemiology Project (a medical records linkage system that captures medical data from electronic and paper medical and autopsy records for patients using the Mayo Clinic, Olmsted Medical Center, their affiliated hospitals, or one private practice provider) | |
| Comparisons | Shorter (2 pages) vs. longer (4 pages); pre‐notification letter vs. postcard | |
| Outcomes | Response after first mailing, response after one reminder (4 wks after first mailing) | |
| Topic | Health (gastrointestinal symptoms and functional gastrointestinal disorder (FGID) diagnoses) | |
| Mode of Administration | Postal | |
| Notes | The varied questionnaire length versions were based on the Talley Bowel Disease Questionnaire (Talley‐BDQ), a self‐report instrument to measure symptoms experienced over the past year. For this experiment, the full 16‐page Talley‐BDQ was shortened to a 4‐page version and then to a 2‐page version. The letter and postcard pre‐notifications contained the same text. Both identified the survey sponsor and described the purpose of the study. All subjects were sent either a letter or a postcard one week prior to mailing the survey package. A week after pre‐notification, a survey package was sent to all potential respondents. The package included a cover letter, a pen incentive, and one of two versions of the modified Talley‐BDQ. Reminder letters, along with another survey, were sent to non‐responders 4 weeks after the first mailing. Subjects who indicated at any point that they did not want to be contacted further were excluded from the study. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (RANUNI function in SAS v. 9.1. software) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (RANUNI function in SAS v. 9.1. software) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | After randomisation, it was discovered that 120 cases were ineligible due to residence outside of Olmsted County or deceased status. |
| Selective reporting | Yes | Responses at all time points were reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Beebe 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Primary care clinicians, including physicians, nurse practitioners, and physician assistants, US | |
| Comparisons | Mixed‐mode (mail with web follow‐up) vs. mixed‐mode (web with mail follow‐up) Mail‐only vs. web‐only |
|
| Outcomes | Response after 2 reminders | |
| Topic | Health (clinician knowledge, clinician barriers, and perceived parental barriers regarding human papillomavirus [HPV] vaccination). | |
| Mode of Administration | Postal & electronic | |
| Notes | Questionnaire not described. A cover letter on Mayo Clinic letter head detailing the survey purpose, the survey booklet, and a SAE. Body of email same; included link to web survey | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | At the end of the study, two responders were found to be non‐clinicians and were excluded from the denominator. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bell 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | People who had signed up for the 'Adventist Health Study‐2' | |
| Comparisons | 1. Follow‐up phone call 2. No follow‐up phone call |
|
| Outcomes | Response within approximately 6 months | |
| Topic | Health: dietary habits and risk of cancer | |
| Mode of Administration | Postal | |
| Notes | Mean age: 67.5 years; additional data obtained from author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Bell 2016.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Women aged 70‐75 years in screening of older women for prevention of fracture trial (SCOOP) recruited through GPs, UK | |
| Comparisons | Pen vs. no pen | |
| Outcomes | First response and response after one reminder (3 weeks) | |
| Topic | Health (self‐reported fracture of any bone in previous 12 months) | |
| Mode of Administration | Postal | |
| Notes | EQ‐5D (2 pages) and SF‐12 (3 pages). SCOOP participants received trial‐branded pen with the 60‐month follow‐up questionnaire, or received questionnaire alone. Reminder notices were sent approximately 18 days after the initial questionnaire. After continued non‐response, a follow‐up telephone call was administered approximately 12 days after the follow‐up reminder notice. After three attempts to contact participants by telephone, the participant was considered a non‐responder. Trial participants were followed up using postal questionnaires at 6 and 12 months post‐randomisation and then annually up to 5 years. The pen trial was initiated in the fifth year of follow‐up when participants were considered most at risk of becoming lost to follow‐up. The final response reported was the number that provided complete primary outcome data. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | First response and response after one reminder (3 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bellizzi 1986.
| Study characteristics | ||
| Methods | Random allocation: random draw | |
| Data | People randomly selected from a local city telephone directory, USA | |
| Comparisons | 1. $1 bill included with questionnaire 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: supermarket shopping | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Berdie 1973.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Staff of University of Minnesota, including professors of each rank | |
| Comparisons | 1. 1‐page questionnaire 2. 2‐page questionnaire 3. 4‐page questionnaire | |
| Outcomes | Response within 20 days | |
| Topic | Non‐health: current social problems | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bergen 1957.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Teachers in municipal elementary schools (Amsterdam) | |
| Comparisons | 1. Pre‐notification 2. None | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bergeson 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients receiving care at six clinics over a four‐month time frame. The clinics represented a mix of rural and urban locations drawn from a large clinic and hospital system in Minnesota. | |
| Comparisons | Web versus mail | |
| Outcomes | Response 88 days post‐visit (1 reminder in mail group, 2 reminders in electronic group) | |
| Topic | Health (patient experiences with care) | |
| Mode of Administration | Postal and electronic | |
| Notes | Consumer Assessment of Healthcare Providers and Systems (CAHPS) Clinician and Group hybrid survey, which includes 22 questions Patients from the clinic sites were randomised to receive either an emailed (web mode) or mailed (mail mode) invitation to complete the survey from the Executive Vice President of the organisation. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | No exclusions reported |
| Selective reporting | Yes | Response 88 days post‐visit (1 reminder in mail group, 2 reminders in electronic group) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Berk 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians | |
| Comparisons | 1. $10 with first mailing; Follow‐up questionnaire and letter mentioning the incentive
2. No incentive with first mailing; follow‐up questionnaire with a $10 incentive and letter explaining the importance of the study
3. No mention of $10 incentive in either first or second mailing Follow‐up sent after 3 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Health: Cost‐effectiveness of 2 alternative methods of diagnosing allergies | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Berry 1987.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physician members of the American Medical Association | |
| Comparisons | 1. Cheque sent with first mailing
2. Promise of cheque with first mailing Non‐responders received a second mailing followed by a telephone call. If they no longer had the questionnaire, a third copy was sent. |
|
| Outcomes | Response period not specified | |
| Topic | Health: evaluation of National Institute of Health Consensus Development Programme | |
| Mode of Administration | Postal | |
| Notes | Mean age: 48 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Beydoun 2006.
| Study characteristics | ||
| Methods | Random allocation: using computerised database | |
| Data | Women of reproductive age residing in Iowa county | |
| Comparisons | 1. Unconditional $5 telephone card + conditional $25 check 2. Conditional $30 check |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Electronic: CATI | |
| Notes | Age: 18‐49 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bhandari 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Surgeon members of the Orthopaedic Trauma Association | |
| Comparisons | 1. Survey endorsed in cover letter by 'opinion leaders' (high‐profile surgeons) 2. Survey not endorsed | |
| Outcomes | Response period not specified | |
| Topic | Health: evaluate surgeons opinions regarding optimal treatment of fractures of the tibial shaft | |
| Mode of Administration | Postal | |
| Notes | Mean age: 30.5 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Biner 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a mid‐western US city | |
| Comparisons | 1. Reactance appeal; $1 incentive 2. Reactance appeal; no incentive 3. No reactance appeal; $1 incentive 4. No reactance appeal; no incentive | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: residents' attitudes about the city | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Biner 1990.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a mid‐western US city | |
| Comparisons | 1. $1 incentive; obligatory cover letter 2. $1 incentive; appreciative cover letter 3. $0.25 incentive; obligatory cover letter 4. $0.25 incentive; appreciative cover letter | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: residents' attitudes about the city | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Biner 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a mid‐western US city | |
| Comparisons | 1. Short questionnaire; $1 incentive and obligatory cover letter 2. Short questionnaire; $1 incentive and appreciative cover letter 3. Long questionnaire; $1 incentive and obligatory cover letter 4. Long questionnaire; $1 incentive and appreciative cover letter | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: residents' attitudes about the city | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Birnholtz 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Users of a collaboratory* for earthquake engineering research | |
| Comparisons | 1. $5 bill 2. Gift certificate for Amazon.com |
|
| Outcomes | Response period was 6 weeks | |
| Topic | Non‐health: participants research work and perception of a set of collaboration tools | |
| Mode of Administration | Electronic: web‐based | |
| Notes | Additional data obtained from the author * From the full‐text report: “A collaboratory is a kind of laboratory without walls that connects scientists, instruments, and data via computer networks.” |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computerised random number generation |
| Allocation concealment? | Yes | Random allocation: computerised random number generation |
| Blinding of participants and personnel | Unclear | Blinding of personnel unspecified. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not specified |
| Selective reporting | Yes | Response at 6 weeks was specified and reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bjertnaes 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Women who gave birth at a university hospital | |
| Comparisons | Electronic and postal options for first and second mailing vs. electronic only first mailing and electronic and postal options for second mailing | |
| Outcomes | Response after 1 reminder (after 3 weeks) | |
| Topic | Health (experiences with healthcare services during pregnancy and birth, and after birth) | |
| Mode of Administration | Postal & electronic | |
| Notes | Questionnaires 16 pages; 141 questions. The information letter in the first survey request was the same for both groups, the only exception being the inclusion of an Internet link, user name, and password for electronic response in first mailing group. The second survey request was made to non‐respondents 3 weeks after posting the initial request, with both groups presented with an opportunity to answer via either post or the Internet. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | 9 women failed to receive the survey due to wrong contact information. |
| Selective reporting | Yes | Response after 1 reminder (after 3 weeks) reported in full |
| Other sources of bias | Yes | Non‐response and other sources of bias considered |
Bjertnaes 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Parents of 2606 patients registered in the Norwegian Childhood Diabetes Registry | |
| Comparisons | Postal only vs. mixed‐mode (postal/electronic) vs. electronic only | |
| Outcomes | Response after 6 weeks (2 reminders) | |
| Topic | Health (parent experiences with hospital outpatient care for child and adolescent diabetes) | |
| Mode of Administration | Postal and electronic | |
| Notes | 4 pages with 40 questions (5 sociodemographic, 35 topic), and an additional page for comments relating to experiences with the clinic or the questionnaire Parents of the 2606 patients registered in the Norwegian Childhood Diabetes Registry were sent an invitation letter to participate in the study. Two reminders were sent to non‐respondents. First reminder sent approximately 3 weeks after posting the initial request, the second approximately 3 weeks after first. Parents were randomised into the following data collection groups: i) postal with pen‐and‐paper questionnaire; ii) postal with pen‐and‐paper questionnaire and electronic response option; iii) postal with electronic response option. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | Due to wrong addresses, 80 patients were excluded. |
| Selective reporting | Yes | Responses before reminders and after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Blass 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Certified psychologists who did not respond to previous mailing of the questionnaire | |
| Comparisons | 1. Consensus statement; threat of follow‐up 2. Consensus statement; no threat of follow‐up 3. No consensus statement; threat of follow‐up 4. No consensus statement; no threat of follow‐up | |
| Outcomes | Response period not specified | |
| Topic | Health: psychologist behaviour and attitudes towards continuing education | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Blass‐Wilhems 1982.
| Study characteristics | ||
| Methods | Random allocation: random walk sampling | |
| Data | Not known | |
| Comparisons | 1. Real postage stamp 2. Postage paid reply | |
| Outcomes | — | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Blomberg 1996.
| Study characteristics | ||
| Methods | Random allocation: using a list of numbers between 1‐99 selected in a 'random' order by a researcher | |
| Data | Patients at the Stockholm County Council Institute of Psychotherapy | |
| Comparisons | 1. Questionnaire with promise of lottery ticket on response
2. Questionnaire with lottery ticket enclosed
3. Questionnaire with no incentive All non‐respondents were sent reminders at 3, 6 and 10 weeks after initial mailing. At 14 weeks, non‐responders were sent a brief questionnaire regarding their reasons for not responding. |
|
| Outcomes | Response within 12 weeks. Response period for second questionnaire not specified | |
| Topic | Health: psychotherapy measures ‐ General Symptom Index, Sense of Coherence, and Change in Target Complaints | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Author confirmed allocation concealment. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Blumenberg 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Mothers of 5914 hospital births occurring in Pelotas (Brazil) in 1982 (Pelotas birth cohort study) | |
| Comparisons | Short vs. longer questionnaire high (every 15 days) vs. low (every 30 days) frequency of reminders (by email, Whatsapp, or Facebook message) | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (alcohol consumption, physical activity, Internet use, violence, and smoking) | |
| Mode of Administration | Electronic (Web) | |
| Notes | Short questionnaires included 11 to 17 items (4 mins to complete); long questionnaires included 21 to 33 items (14 mins to complete) Applied 5 web‐questionnaires using 2 lengths (short and long version). Reminders were sent to non‐respondents using the same methods used for recruitment: emails, Whatsapp and Facebook messages; we sent, at most, two reminders for each questionnaire. If the registered individual had responded to that questionnaire, no further reminders were sent until a new questionnaire was published on the platform. Individuals allocated to the high‐frequency group received reminders every 15 days, while those in the low‐frequency group received reminders every 30 days. (Outcome data estimated from Fig 1a) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | The randomisation process was blind, and registered individuals did not know to which group they were allocated. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Blythe 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Social workers | |
| Comparisons | 1. Questionnaire with an opportunity to enter a lottery
2. Questionnaire without lottery offer Reminder letter sent after 1 week. Non‐respondents followed up at 3 and 7 weeks with offer to participate in the lottery. |
|
| Outcomes | Response within 30 days | |
| Topic | Health: application of clinical evaluation tools in practice | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bolt 2014.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2500 physicians: 1000 medical specialists (250 internists, 150 cardiologists, 150 intensive care physicians, 150 neurologists, 150 pulmonologists, and 150 surgeons), 1100 GPs, and 400 elderly care physicians | |
| Comparisons | Long (4 double pages) vs short (2 double pages) questionnaire | |
| Outcomes | Response after 3 months and after 2 reminders | |
| Topic | Healthcare; physician questionnaire on end‐of‐life decision‐making | |
| Mode of Administration | Postal | |
| Notes | Four double‐page questionnaire (54 questions) or a shorter version consisting of two double pages (27 questions); all physicians were asked to return a response card stating whether they would participate and, if not, they were asked for their reason for not participating. After 1 month, physicians who had not returned this card received a reminder package containing the same questionnaire and a letter with a link to a questionnaire online. After 3 months, the remaining non‐responders received a reminder package containing a one double‐page questionnaire (18 questions). The original questionnaire consisted of four double pages (2727 to 2891 words, 54 to 58 questions, depending on specialty). The 1000 medical specialists were randomly assigned to receive the four double‐page questionnaire (2730 words, 54 questions) or a shorter version consisting of two double pages (1471 words, 27 questions) in which in‐depth questions and questions about the most recent request for euthanasia were omitted. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | Of the 2500 physicians, 231 were not traceable or not working in patient care in one of the included specialities. |
| Selective reporting | Yes | Response after 3 months and after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bond 2020.
| Study characteristics | ||
| Methods | Random allocation: computer random number generator | |
| Data | Breastfeeding women in a trial of an oral probiotic versus a placebo for preventing mastitis | |
| Comparisons | Mobile phone automated system (MPAS) vs. paper and email data collection (PEDC) | |
| Outcomes | Outcome data for the first 8 weeks and follow‐up questionnaires at 2, 6, and 12 months | |
| Topic | Health: prevention of mastitis | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire not described in this report Short daily and slightly longer weekly questionnaires during the first 8 weeks following birth and longer follow‐up questionnaires at 2, 6, and 12 months [Arm 1]: The MPAS sent automated text messages to the participants' mobile phones with links to self‐administered web‐based surveys. Each survey link was embedded with the participants' unique identifier, enabling comparison across multiple surveys. A maximum of 2 automated reminders were integrated into the system if a participant did not respond after 3 days. [Arm 2]: The PEDC included a combination of an 8‐week calendar diary provided to participants at the time of trial entry and emailed links to weekly and follow‐up surveys. The calendar diaries were identified with the participant study number at the time of treatment randomisation, and the start date was manually entered. The A4‐size calendar was preserved with a waterproof coating, allowing for daily entries by pen. Participants were encouraged to hang the calendar in a prominent place at home. PEDC users were supplied with a stamped, addressed envelope to post the calendar back to the trial co‐ordinating centre at the end of the treatment phase. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated random number |
| Allocation concealment? | Yes | Random allocation: computer‐generated random number |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Losses to follow‐up reported for both arms of the trial |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bonevski 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random sample of 500 GPs practising in New South Wales (NSW), Australia | |
| Comparisons | Standard (Cancer Council NSW) invitation letter vs. standard invitation letter plus local Hunter urban Division of General Practice (GP access) cover letter signed by the chief executive | |
| Outcomes | First response, second response after reminder sent 4‐6 weeks after first mailing | |
| Topic | Healthcare: knowledge and attitudes about/practices around vitamin D of GPs | |
| Mode of Administration | Postal | |
| Notes | 31 items about vitamin D printed on bright yellow paper. Study materials were mailed to all GPs. An information letter informed them of the study, and a note (with tea and coffee sachets attached) asked GPs to 'take a break from their busy day' and complete the survey. General practitioners were offered two options for completion and return of the survey: online, using a website address provided in the information letter; or hardcopy, using the paper version sent with the letter (with a reply‐paid envelope and a facsimile number included for return of the paper version of the survey). Completion of the survey constituted consent. General practitioners who completed the survey were offered the chance to receive a holiday voucher valued at $500. About 4‐6 weeks after the initial mailout, a reminder mailout was sent to GPs who had not responded to the survey. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Of the 1666 GPs selected in the sample, 52 were ineligible (retired, no longer working in general practice, or moved from practice). |
| Selective reporting | Yes | Responses to both mailouts and reminder telephone calls were reported in full. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bonevski 2011a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random sample of 500 GPs practising in New South Wales (NSW), Australia | |
| Comparisons | Telephone reminder vs. no reminder | |
| Outcomes | First response, second response after reminder sent 4‐6 weeks after first mailing | |
| Topic | Healthcare: knowledge and attitudes about/practices around vitamin D of GPs | |
| Mode of Administration | Postal | |
| Notes | 31 items about vitamin D printed on bright yellow paper. Study materials were mailed to all GPs. An information letter informed them of the study, and a note (with tea and coffee sachets attached) asked GPs to 'take a break from their busy day' and complete the survey. General practitioners were offered two options for completion and return of the survey: online, using a website address provided in the information letter; or hardcopy, using the paper version sent with the letter (with a reply‐paid envelope and a facsimile number included for return of the paper version of the survey). Completion of the survey constituted consent. General practitioners who completed the survey were offered the chance to receive a holiday voucher valued at $500. About 4‐6 weeks after the initial mailout, a reminder mailout was sent to GPs who had not responded to the survey. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Of the 1666 GPs selected in the sample, 52 were ineligible (retired, no longer working in general practice, or moved from practice). |
| Selective reporting | Yes | Responses to both mailouts and reminder telephone calls were reported in full. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Boser 1990.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Graduates from the College of Education of a major university (US) | |
| Comparisons | 1. Questionnaire in folder format 2. Questionnaire in stapled format | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: teaching | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Bosnjak 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Local professional sales association members in the mid‐Atlantic US | |
| Comparisons | 1. Unconditional $2 via PayPal 2. Conditional $2 3. Conditional prize draw (two $50 and four $25 prizes) 4. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: trends and concerns in real estates | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Boulianne 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | First‐year students at Grant MacEwan University, Alberta, Canada | |
| Comparisons | Unconditional $5 incentive vs. unconditional $10 incentive | |
| Outcomes | Break‐offs and completed surveys | |
| Topic | Non‐health: community attachment, membership in various groups, civic ethics, civic engagement, political engagement, and media usage | |
| Mode of Administration | Web survey | |
| Notes | The survey instrument included questions about community attachment, membership in various groups, civic ethics, civic engagement, political engagement, and media usage Pre notification letter with cash attached, hand‐signed and printed on university letterhead. Followed by email survey invitation |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not reported. Participants were not blinded to intervention |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions clearly reported |
| Selective reporting | Yes | Breakoffs and completed surveys reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Boyd 2015.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (random number generator within Stata) | |
| Data | Index children of the Avon Longitudinal Study of Parents and Children cohort (ALSPAC) | |
| Comparisons | Prior‐notification postcard vs. no contact; standard vs. professionally designed consent pack; phone (phone call, SMS, or email) reminder vs. postcard reminder | |
| Outcomes | Response after 3 weeks; response after reminder | |
| Topic | Health: consent to be enrolled into the ALSPAC cohort study including linking their health records | |
| Mode of Administration | Postal | |
| Notes | A single consent form (which asked multiple, separate, consent questions). Information materials split into: a covering letter, a four‐page summary leaflet, a 32‐page detailed booklet supported by detailed Web pages. A prepaid envelope was included. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (random number generator within Stata) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (random number generator within Stata) |
| Blinding of participants and personnel | Yes | At the point of allocation, the participants were identified using the pseudonym key and K.H. administered the distribution and collation of the prior‐notification and the information pack interventions. |
| Blinding of outcome assessment | Yes | No outcome asessment used (counts of responses only) |
| Incomplete outcome data | Yes | Where there was evidence that the mailing was not received (the mailing being returned "addressee not known, by the postal service or participants requesting replacement mailings), we excluded the individual from the analysis [n = 548 (2.4%)], resulting in an analysable sample of 1950. |
| Selective reporting | Yes | Response after one reminder was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Boyle 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | People aged between 40 and 79 randomly selected from the electoral roll, Australia | |
| Comparisons | Unconditional $2 lottery scratch ticket vs. nothing | |
| Outcomes | Non‐responders were sent a reminder letter 3 weeks after the initial invitation. | |
| Topic | Health: colorectal cancer | |
| Mode of Administration | Postal | |
| Notes | Consent form for the Western Australian Bowel Health Study (WABOHS) (presumably 2 or 3 questions) Invitation letter, an information sheet about the study, a consent form, and a reply‐paid envelope Participants who consented to take part in the WABOHS were then sent a study pack that consisted of two questionnaires and a DNA self‐extraction kit. These participants were randomised further into three groups when sent their study packs, ignoring their initial allocation to unconditional $2 lottery scratch ticket. Group 0 did not get a lottery scratch ticket, Group 1 received a $2 lottery scratch ticket, and Group 2 was promised a $2 lottery scratch ticket on return of their completed study pack. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Method of randomisation unspecified |
| Allocation concealment? | Unclear | Method of randomisation unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blind to the intervention. |
| Blinding of outcome assessment | Yes | No outcome asessment used (counts of responses only) |
| Incomplete outcome data | Yes | 4 participants were reported ineligible. |
| Selective reporting | Yes | All response outcomes were reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bradshaw 2020.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Parents who had given consent for their infant to be randomised into the BEEP host trial | |
| Comparisons | Pre‐contact by SMS at 3 m, 6 m, 12 m and 18 m vs. no SMS | |
| Outcomes | Response 28 days after SMS | |
| Topic | Health (effect of applying emollient on development of eczema in high‐risk infants) | |
| Mode of Administration | Electronic (web‐link sent by email) with postal option | |
| Notes | Questionnaires had 14 items on one page. Electronic (web‐link sent by email) with postal alternative for parents who did not want to respond online Due to the lower than expected completion of questionnaires, the protocol was amended in May 2016 to allow members of the host trial team to telephone participants where questionnaires had not yet been completed but were still active. Text messages or emails were also sent by the trial team when they were unable to reach participants by telephone. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Participants were informed in the host trial information sheet about the randomized controlled study within a trial (SWAT) for SMS notification for questionnaires and timing of the voucher for the 24‐month visit but were not informed at the time of their randomisation of their allocated groups for the SWAT. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response data reported for all follow‐up times |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bray 2017.
| Study characteristics | ||
| Methods | Randomisation of participants was carried out using the runiform function in Stata with anonymous identifiers. | |
| Data | Young people in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort study, UK | |
| Comparisons | Online questionnaire vs. choice (online or postal) | |
| Outcomes | The primary outcome measure was the number of questionnaires returned (with at least one question answered) in each arm of the trial. For the purposes of this analysis, return rates were calculated 30 weeks after the initial mailing. | |
| Topic | Health: gambling, self‐harm, employment, education & training, and tobacco & alcohol | |
| Mode of Administration | Electronic and postal | |
| Notes | The paper version of the questionnaire was an A5 booklet of 44 pages; the online questionnaire was designed to be as similar as possible to the paper questionnaire, acknowledging that certain functions, such as skip statements, would be different because participants would be automatically directed to the next relevant question. This also affected the numbering of questions, which would have been non‐consecutive if not allowed to be dynamic in the online version. Generally, the number of questions per page was less in the online version than in the paper version. The first reminder (after 3 weeks) was by email, but if an email address was not recorded, then a text was used. If neither electronic means of contact was possible, then a postcard reminder was used. Two weeks later, a different mode of reminder was sent (unless a postcard had already been used in which case no other reminder was sent, to avoid multiple reminders of the same method). Eight weeks after the initial letter, a reminder letter was sent to all non‐respondents, with a paper copy of the questionnaire enclosed. Another brief reminder (email, text, or postcard) was sent if necessary 2 weeks later. A Facebook reminder was also posted 12 weeks after the original letter. Finally, a phone call reminder was attempted for all those who had not responded between 12 and 19 weeks after the initial letter was sent out. Initially, an attempt was made to contact the participant using the landline number held on record. If this was not successful and if a mobile number was also recorded, then this number was also rung. If neither attempt was successful, then a message was left on both landline and mobile phones, wherever possible. If contact was made with a family member but the participant was not at home, then a message was left. A reminder was sent only if a paper questionnaire had not been received from the participant and the online submission was not complete (i.e. at least one section of the questionnaire had not been submitted online). The exception to this was the reminder at 8 weeks enclosing a paper questionnaire; this was only sent if a paper questionnaire had not been received and an online submission had not been initiated (i.e. no sections had been submitted online). If a participant contacted ALSPAC to request a paper questionnaire at any stage in the process, then this was recorded and one was sent. A £10 Amazon voucher was offered to compensate participants for their time and to encourage response. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: conputer‐generated (runiform function in Stata with anonymous identifiers) |
| Allocation concealment? | Yes | Random allocation: conputer‐generated (runiform function in Stata with anonymous identifiers) |
| Blinding of participants and personnel | Yes | ALSPAC staff compiling the completion statistics were blinded to group assignment. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | It was discovered that 13 participants in the ‘‘online first’’ arm (0.3%) and 17 in the ‘‘choice’’arm (0.4%) were not eligible (e.g. due to changes in family circumstances or requests not to be contacted) and were therefore not mailed. |
| Selective reporting | Yes | Responses after 30 weeks from initial mailing were reported in full. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bredart 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Breast cancer patients undergoing surgical treatment within the surgery department of the European Institute of Oncology in Milan | |
| Comparisons | 1. Questionnaire sent 2 weeks after hospital discharge 2. Questionnaire sent 3 months after hospital discharge | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Breen 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | People aged 18‐37 years who did not respond to three mailings of a postal community survey investigating alcohol consumption and harm in rural NSW, Australia | |
| Comparisons | Follow‐up phone call vs. no further contact | |
| Outcomes | Response after 9 weeks (after 2 reminders) | |
| Topic | Health: alcohol consumption and harm | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Questionnaire sent with a personalised cover letter; returns were tracked; reminders sent after 1 week and after 2 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | 12 participants were overseas, away, or had died. |
| Selective reporting | Yes | Responses after reminders and intervention phone call reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Brehaut 2006.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Members of the Canadian Association of Emergency Physicians | |
| Comparisons | 1. Single‐sided print format 2. Double‐sided print format 3. Known sender recognition 4. Unknown sender recognition |
|
| Outcomes | Response period not specified | |
| Topic | Health: clinical decision rules | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computerised random number generation |
| Allocation concealment? | Yes | Random allocation: computerised random number generation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Our initial sample consisted of 400 names. Of those, one was ineligible due to an address outside of Canada.. |
| Selective reporting | Yes | Response after three mailings was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Brems 2006.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Licenced healthcare professionals from Alaska and New Mexico in the US | |
| Comparisons | 1. First‐class mail 2. Priority mail |
|
| Outcomes | Response period not specified | |
| Topic | Health: range of treatment used by physical and behavioural healthcare providers, ethical issues | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Brennan 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on 1 of the 57 electoral rolls representing the main urban centres, New Zealand | |
| Comparisons | 1. Control ‐ no incentive 2. 20c coin with first mailing 3. 50c coin with first mailing 4. $1 note with first mailing 5. 20c coin with second mailing 6. 50c coin with second mailing 7. $1 note with second mailing 8. Entry into prize draw for $200 cash offered with each mailout 9. Entry into prize draw for $200 gift voucher offered with each mailout | |
| Outcomes | Response within 21 days of the third mailing (49 days after initial mailing) | |
| Topic | Non‐health: personal finance status | |
| Mode of Administration | Postal | |
| Notes | Randomisation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 1992a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on a financial service company's 'hot prospect' list | |
| Comparisons | 1. $0.50 incentive 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: finances and shopping behaviours | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 1992b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on the electoral roll (New Zealand) | |
| Comparisons | 1. $0.50 incentive 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: finances and shopping behaviours | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 1992c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on the electoral roll (New Zealand) | |
| Comparisons | 1. $0.50 incentive 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: finances and shopping behaviours | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 1993a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Dairy and beef farmers | |
| Comparisons | 1. $0.50 coin with first mailing 2. $1 coin with first mailing 3. $1 lottery ticket with first mailing 4. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 1993b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on the electoral roll (New Zealand) | |
| Comparisons | 1. $0.50 coin with first mailing 2. $1 coin with first mailing 3. Promise that $1 would be donated to a charity for each valid return (in each of 3 mailings) 4. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brennan 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | New Zealand residents selected from the electoral roll | |
| Comparisons | Unconditional chocolate incentive vs. none | |
| Outcomes | Response after two follow‐ups | |
| Topic | Non‐health (Reality TV) | |
| Mode of Administration | Postal | |
| Notes | Eight‐page questionnaire on the topic of Reality TV was in the form of an A4 international standard size booklet (A3 international standard equivalent folded), in one of four bold colours (green, blue, red, and purple). A reply‐paid envelope was provided whenever a questionnaire was supplied. The one‐page cover letter was printed on the university letterhead. It explained what the survey was about and why it was being conducted; assured respondents that the survey was simple and not trying to trick them or sell them anything; explained how they were selected; stressed confidentiality; explained the purpose of the ID number; informed them of the reply‐paid envelope; acknowledged that they were busy and expressed appreciation in advance for their assistance. Shortened forms of this letter, emphasising the importance of a response and appreciation of their assistance, were used in the follow‐up mailouts. All envelopes had the university logo printed in the top left‐hand side corner. The incentive was a small (45 mm x 55 mm x 6 mm), flat, individually foil‐wrapped high‐quality milk chocolate bar. This chocolate remains solid at temperatures considerably higher than those likely to be encountered by the mail, so there was minimal likelihood of the chocolate melting. The colours of the packaging (blue and gold) co‐incidentally matched the colours of the university letterhead used for the cover letters, making for an appealing package. The incentive (when used) was attached to the letter with double‐sided adhesive tape, and the following statement was added to the letter: 'As a token of our appreciation, we hope you will enjoy the attached sample of Whittaker's chocolate.' Whittaker's is a long‐established, well‐known New Zealand chocolate manufacturer. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after two follow‐ups reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Bright 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | US Marinas | |
| Comparisons | 1. Offer of entry into a prize draw and summary of study results on return of questionnaire 2. No incentive offered | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceptions of decision‐makers at US Marinas | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brook 1978.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | People who had been interviewed when shopping (Southampton, UK) | |
| Comparisons | 1. First‐class stamp out; first‐class stamp return 2. First‐class stamp out; second‐class stamp return 3. Second‐class stamp out; first‐class stamp return 4. Second‐class stamp out; second‐class stamp return 5. First‐class stamp out; second‐class business reply return 6. Second‐class stamp out; second‐class business reply return | |
| Outcomes | Response within 2 weeks | |
| Topic | Non‐health: marketing | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Brookes 2018a.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated schedule | |
| Data | 130 consenting living patients who had undergone oesophagectomy from 2 UK hospital trusts | |
| Comparisons | Patient‐reported outcomes (PROs) first and clinical outcomes last vs. clinical outcomes first and PROs last Brookes 2018a in patients; Brookes 2018b in healthcare professionals |
|
| Outcomes | Response after reminders | |
| Topic | Health (outcomes following oesophageal cancer surgery) | |
| Mode of Administration | Postal | |
| Notes | 8 PROs and 30 clinical outcomes Patients were posted an invitation letter and information leaflet and asked to return a consent form indicating willingness to participate in the study. Consenting patients were then sent a postal survey with an SAE. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated schedule |
| Allocation concealment? | Yes | Allocation schedule was used (within a mail‐merge) to automatically generate the allocated survey for each participant |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Brookes 2018b.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated schedule | |
| Data | 96 relevant health professionals (from Association of Upper GastroIntestinal Surgeons of Great Britain and Ireland) | |
| Comparisons | Patient‐reported outcomes (PROs) first and clinical outcomes last vs. clinical outcomes first and PROs last Brookes 2018a in patients; Brookes 2018b in healthcare professionals |
|
| Outcomes | Response after reminders | |
| Topic | Health (outcomes following oesophageal cancer surgery) | |
| Mode of Administration | Postal | |
| Notes | 8 PROs and 30 clinical outcomes Professionals were notified by email about the study and sent a survey through the post with an SAE. Reminders were sent via post or email (for patients and professionals, respectively) to non‐responders. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated schedule |
| Allocation concealment? | Yes | Allocation schedule was used (within a mail‐merge) to automatically generate the allocated survey for each participant |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Brown 1965.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Non‐paediatric physicians (US) | |
| Comparisons | 1. 2‐page questionnaire (first page was letter with 2 cystic fibrosis screening questions; second page asked for details of patients seen) 2. 1‐page cover letter and postcard with 2 cystic fibrosis screening questions | |
| Outcomes | Response period not specified | |
| Topic | Health: cystic fibrosis | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brown 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Officers and enlisted men | |
| Comparisons | 1. Pre‐notification; randomised enquiry method 2. No pre‐notification; randomised enquiry method 3. Pre‐notification; conventional method 4. No pre‐notification; conventional method | |
| Outcomes | Response period not specified | |
| Topic | Health: assessment of illicit drug use | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Bruce 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People randomly selected from households in central Sydney (Australia) who had agreed to participate during an earlier phone interview | |
| Comparisons | 1. Phone call reminder to non‐responders 2. Postcard reminder to non‐responders | |
| Outcomes | Response period not specified | |
| Topic | Health: colorectal cancer screening | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Brøgger 2007.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Permanent residents of Norway | |
| Comparisons | 1. Postal plus optional Internet response 2. Only postal response |
|
| Outcomes | Response period not specified | |
| Topic | Health: respiratory survey (to establish the occurrence and risk factors for asthma and allergies) | |
| Mode of Administration | Postal | |
| Notes | Mean age: 30.7 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants were blinded to the randomised nature of the study. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions and attrition reported |
| Selective reporting | Yes | Outcomes reported fully |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Buchman 1982.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Certified public accountants | |
| Comparisons | 1. Conventional questionnaire 2. Randomised response technique employed for each question | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: audit procedures | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Burgess 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Practice managers of general practices in two inner London boroughs, UK | |
| Comparisons | Electronic reminders vs. electronic and postal reminders | |
| Outcomes | Response after 2 reminders (after 1 and 2 weeks) | |
| Topic | Health; evaluation of implementation of NHS Health Checks | |
| Mode of Administration | Electronic and mixed‐mode (electronic and postal) | |
| Notes | 33 questions. (i) computer‐delivered survey only with email reminders after 1 and 2 weeks; (ii) sequential, mixed‐mode with computer‐delivered survey followed by both email and postal reminder letters after 1 and 2 weeks. The postal reminder included a paper copy of the questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding not reported. Participants could not be blinded. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Responses after reminders fully reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Burns 1980.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A random sample of bank and savings and loan chief executive officers, USA | |
| Comparisons | 1. No incentive; no follow‐up 2. 25 cent incentive; no follow‐up 3. 25 cent incentive; follow‐up postcard sent 10 days after initial mailing 4. No incentive; follow‐up postcard sent 10 days after initial mailing | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: commercial population | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Buttle 1997.
| Study characteristics | ||
| Methods | Random allocation | |
| Data | Managing Directors of the companies listed on the DTI Quality Assurance Register 1995 | |
| Comparisons | 1. Questionnaires printed on white paper 2. Questionnaires printed on yellow paper |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceived costs and benefits of ISO 9000 in certified organisations | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Cabana 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Paediatricians listed as general paediatricians in the American Medical Association master file | |
| Comparisons | 1. Survey logo on questionnaire only 2. Survey logo on cover letter, return envelope, questionnaire and outer envelope | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Campbell 1990.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on the electoral roll (Southampton, UK) | |
| Comparisons | 1. Participants told replies would be anonymous 2. Participants told replies would not be anonymous and would be followed up after 3 weeks | |
| Outcomes | Response period not specified | |
| Topic | Health: knowledge of AIDS | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Camunas 1990.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Nurses who were members of the New York State Nurses Association | |
| Comparisons | Experiment 1:
1. Questionnaire, cover letter and brochure
2. Questionnaire, cover letter with an invitation to join the Nursing Association and brochure
3. Questionnaire and cover letter only Experiment 2: 1. Questionnaire, cover letter and $1 bill incentive 2. Questionnaire and cover letter only Questionnaires were colour‐coded for each group. No pre‐contact or follow‐up used |
|
| Outcomes | Response period not specified | |
| Topic | Health: professional membership behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Carling 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Journalists in the health field | |
| Comparisons | 1. International postal vouchers 2. No International postal vouchers |
|
| Outcomes | Response period not specified | |
| Topic | Health: barriers and facilitators to high‐quality health journalism | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Carpenter 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed on an automobile registration list (Arizona, US) | |
| Comparisons | 1. Least personalised questionnaire 2. Somewhat personalised questionnaire 3. Most personalised questionnaire 4. Control group | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: migration behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Carpenter 1977.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Heads of households and their spouses selected from the annually compiled auto registration list | |
| Comparisons | 1. 2 questionnaires allocated per household 2. 1 questionnaire allocated per household | |
| Outcomes | Response within 7 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Cartwright 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Recent mothers | |
| Comparisons | Experiment 1:
1. Long questionnaire about facts and attitudes
2. Medium questionnaire about facts and attitudes
3. Short questionnaire about facts and attitudes
4. Long questionnaire about facts only
5. Medium questionnaire about facts only
6. Short questionnaire about facts only Experiment 2: 1. Government department sponsor (OPCS, UK) 2. University sponsor (Institute for Social Studies in Medical Care) Experiment 3: 1. Asked to tick boxes in response 2. Asked to ring pre‐codes in response |
|
| Outcomes | — | |
| Topic | Health: maternity | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Cartwright 1987.
| Study characteristics | ||
| Methods | Random allocation: systematic division | |
| Data | Elderly people from the electoral registers in Woodford and Wanstead, London and Blackley, Manchester, UK | |
| Comparisons | 1. Shorter questionnaire (2 questions) 2. Longer questionnaire (5 questions) | |
| Outcomes | — | |
| Topic | Health: medication and relationship with GPs | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Chan 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Chinese Medicine Practitioners registered with the Chinese Medicine Council of Hong Kong | |
| Comparisons | 1. HK $20 2. HK $30 3. No Incentives |
|
| Outcomes | Response period not specified | |
| Topic | Health: knowledge, attitudes, and practices on computers and computer use in clinical practice | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly 40‐59 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Chan 2018.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated list | |
| Data | Registered medical doctors of the Medical Council of Hong Kong | |
| Comparisons | Standard invitation letter vs. invitation with motivational message vs. motivational message on follow‐up reminder | |
| Outcomes | Response after 2 weeks | |
| Topic | Health (evaluation of physicians' attitudes toward people with mental illness) | |
| Mode of Administration | Mixed‐mode (postal or web) | |
| Notes | Questionnaire 20 mins; 5 pages; double‐sided Invitation letter with URL mailed, with consent form, questionnaire and SAE. Conditional coupon (HK$50) offered on returned questionnaire Promotion‐focused message (emphasising the promotion of mental healthcare through survey participation), prevention‐focused message (emphasising the reduction of psychiatric stigma by survey participation) or neutral message. Message on 1st mailing or on reminder |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated list |
| Allocation concealment? | Yes | Random allocation: computer‐generated list |
| Blinding of participants and personnel | Yes | Individuals invited to participate in the survey were blinded to the design of this randomized trial. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 2 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Chebat 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | The Quebec population within the legal driving age | |
| Comparisons | 1. Pre‐notification; non‐monetary incentive 2. Pre‐notification; no incentive 3. No pre‐notification; non‐monetary incentive 4. No pre‐notification; no incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: driving behaviour | |
| Mode of Administration | Postal | |
| Notes | Method of allocation and concealment ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Chen 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students from 4 Taipei Universities | |
| Comparisons | 1. Long questionnaire ‐ 5 pages 2. Short questionnaire ‐ 2 pages 3. High salient topic ‐ cutting‐class behaviours in undergraduates 4. Low salient topic ‐ cutting‐class behaviours in PhD students 5. High authority researcher ‐ university professor with a PhD in Psychology 6. Low authority researcher ‐ student from the Psychology department |
|
| Outcomes | Response period within 10 days | |
| Topic | Non‐health: class‐cutting behaviour | |
| Mode of Administration | Postal | |
| Notes | Language of publication is Chinese. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Childers 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Agents of large Midwest‐based multiple‐line insurance company (US) | |
| Comparisons | 1. Advance letter with commitment postcard. Asked to return the postcard to say if will participate and how long they will take to respond. 'Yes' responses then sent a questionnaire.
2. Advance letter with commitment postcard. Asked to return the postcard only to say if will participate. 'Yes' responses then sent questionnaire.
3. Control ‐ no prior commitment sought. All sent questionnaires Reminder postcards sent after 4 days. Non‐respondents sent another questionnaire after 3 weeks |
|
| Outcomes | — | |
| Topic | Non‐health: insurance | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Childers 1980a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Academics on the American Marketing Association Roster | |
| Comparisons | 1. Egoistic appeal; handwritten postscript
2. Egoistic appeal; typed postscript
3. Help the sponsor appeal; handwritten postscript
4. Help the sponsor appeal; typed postscript
5. Social utility appeal; handwritten postscript
6. Social utility appeal; typed postscript All participants received reminders after 1 week. |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing texts | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Childers 1980b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Business practitioners on a mailing list of a major south‐western university (US) | |
| Comparisons | 1. Egoistic appeal; handwritten postscript
2. Egoistic appeal; typed postscript
3. Help the sponsor appeal; handwritten postscript
4. Help the sponsor appeal; typed postscript
5. Social utility appeal; handwritten postscript
6. Social utility appeal; typed postscript All participants received reminders after 1 week. |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing texts | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Childers 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Policyholders of a national insurance company (US) | |
| Comparisons | 1. Computer‐printed outgoing envelope; computer‐printed return‐envelope; cover letter explained name and address were for research only. 2. Computer‐printed outgoing envelope; computer‐printed return‐envelope; cover letter did not explain name and address were for research only. 3. Computer‐printed outgoing envelope; participants given provision to write own name and address on return‐envelope; cover letter explained name and address were for research only. 4. Computer‐printed outgoing envelope; participants given provision to write own name and address on return‐envelope; cover letter did not explain name and address were for research only. 5. Labelled address on outgoing envelope; computer‐printed return address; cover letter explained name and address were for research only. 6. Labelled address on outgoing envelope; computer‐printed return address; cover letter did not explain name and address were for research only. 7. Labelled address on outgoing envelope; participants given provision to write own name and address on return‐envelope; cover letter explained name and address were for research only. 8. Labelled address on outgoing envelope; participants given provision to write own name and address on return‐envelope; cover letter did not explain name and address were for research only. | |
| Outcomes | Response within 12 days | |
| Topic | Non‐health: payment of car insurance | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Childers TL 1979.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | American marketing association practitioner members | |
| Comparisons | 1. Small paper size (8½ X 11") 2. Large paper size (8½ X 14") 3. Single‐sided 4. Double‐sided |
|
| Outcomes | — | |
| Topic | Non‐health: marketing concepts, employment features | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Choi 1990.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Members of the Ontario Nurses' Association | |
| Comparisons | 1. No stamp on return envelope 2. Business‐reply stamp 3. Metered stamp 4. Small regular stamp 5. Large commemorative stamp | |
| Outcomes | Response within 92 days | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Choudhury 2012.
| Study characteristics | ||
| Methods | Random allocation: web‐based random number programme | |
| Data | White British/Irish and Bangladeshi residents in Tower Hamlets, London, UK | |
| Comparisons | Handwritten envelope vs. word‐processed address in window envelope | |
| Outcomes | Response period not specified | |
| Topic | Health (chronic pain) | |
| Mode of Administration | Postal | |
| Notes | 2‐page questionnaire The Tower Hamlets Pain Study (TOPAS), to compare the population burden of chronic pain in White British/Irish and Bangladeshi residents in Tower Hamlets, the third most economically deprived part of the United Kingdom, where many people do not speak English, and literacy levels are poor (Tower Hamlets Public Health Report, 2007). We translated our postal questionnaires into Bengali and produced phonetic translations into Sylheti for use by the researchers in face‐to‐face interviews and over the telephone. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: web‐based random number programme |
| Allocation concealment? | Yes | Random allocation: web‐based random number programme |
| Blinding of participants and personnel | Unclear | Blinding of personnel was not reported, and participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Attrition and exclusions reported for all outcomes |
| Selective reporting | Unclear | Response period and number of reminders used not reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Christensen 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Adults resident in Denmark January 2017 | |
| Comparisons | Motivational sentence in the cover letter intended to heighten perceptions of relevance of the survey vs. no motivational sentence in the cover letter | |
| Outcomes | Response period not specified | |
| Topic | Health (Danish Health and Morbidity Survey) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire included a minimum of 52 questions. Included questions on, for example, sociodemographic factors, quality of life, long‐standing illness, health behaviour, contact with health services and social relations, the 12‐Item Short‐Form Health Survey v2, the Perceived Stress Scale and a screening tool for alcohol abuse (the
CAGE‐C test. Two reminders were sent via the regular postal service. In the introductory letter and the second reminder, a paper questionnaire and a prepaid return envelope were enclosed. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | The overall response rate was reported for both arms of the trial. No other response times were measured. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Christie 1985.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | People aged 18+ years listed in the 1984 Auckland telephone directory, New Zealand | |
| Comparisons | 1. Handwritten signature on covering letter (HW); actual age and income asked for (AAI); typed address on outgoing envelope (Ty) 2. HW; AAI; handwritten address on outgoing envelope (HE) 3. HW; age and income bracket asked for (AIB); Ty 4. HW; AIB; HE 5. Typed signature on covering letter (T); AAI; Ty 6. T; AAI; HE 7. T; AIB; Ty 8. T; AIB; HE | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing ‐ awareness of macadamia nuts, purchase behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Church 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Wright County in Minnesota, US | |
| Comparisons | 1. Only questionnaire 2. Questionnaire + Faecal Occult Blood Test (FOBT) ‐ no reminder 3. Questionnaire + Faecal Occult Blood Test (FOBT) + reminder |
|
| Outcomes | Response period not specified | |
| Topic | Health: colorectal screening | |
| Mode of Administration | Postal | |
| Notes | Mean age: 63 years; mainly females; 49% of participants belonging to group 2 were inadvertently delivered the 1st reminder. | |
Clark 2001.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | All consultants listed on the Royal College of Obstetricians and Gynaecologists database (UK) | |
| Comparisons | 1. Simple plastic ballpoint pen sent with questionnaire 2. No pen | |
| Outcomes | Response period not specified | |
| Topic | Health: views on gynaecological endoscopy | |
| Mode of Administration | Postal | |
| Notes | 1 reminder was sent to all non‐responders 3 months after initial mailing | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Clark 2011.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Director of Nursing and the Administrator in 205 U.S. nursing homes (at least 30 beds, across the 48 contiguous states (excluding Alaska, Hawaii, and Washington, DC) | |
| Comparisons | Mailed vs. Web Short vs. long $35 vs. $50 incentive | |
| Outcomes | Response after 8 weeks (at least one respondent, i.e. Director of Nursing or the Administrator) | |
| Topic | ||
| Mode of Administration | Postal or electronic (web) | |
| Notes | Questionnaire not described. Web option participants were mailed a cover letter with URL; mailed option mailed a cover letter with paper questionnaire and SAE; short questionnaire 5‐10 min questionnaire, vs long 20‐40 mins We were specifically interested in comparing mail versus Internet data collection amongst nursing home providers because of previous studies suggesting particularly little information technology in nursing homes and the concern that nursing home providers may lack Internet access during normal business hours. Each selected facility was contacted by telephone to obtain the names and contact information for the Director of Nursing and the Administrator. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions discussed |
| Selective reporting | Yes | Response after 8 weeks reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Clark 2015.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Current smokers aged 35 or more at participating general practices across the Yorkshire and Humberside area, in the UK | |
| Comparisons | Electronic prompt (2 days after the questionnaire was sent) via SMS or email vs. control | |
| Outcomes | Response after 8 weeks | |
| Topic | Health (chronic obstructive pulmonary disease) | |
| Mode of Administration | Postal (with or without electronic reminders) | |
| Notes | Questionnaire design not described. Two reminder letters were sent in an attempt to encourage response. The first reminder letter was sent 2 weeks after the follow‐up questionnaire, and the second reminder was sent 2 weeks later (i.e. 4 weeks after the follow‐up questionnaire). Study participants received an additional electronic prompt (email and/or text messages) to return their questionnaire or to receive no additional prompt. This was in addition to the two reminder letters that all DOC participants received. Participants were those who supplied mobile phone numbers and/or email addresses. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 8 weeks reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Clark TJ 2001.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | All gynaecologists identified from the British Society of Gynaecological Endoscopy database of members | |
| Comparisons | 1. Questionnaire and covering letter printed on standard quality white paper 2. Questionnaire and covering letter printed on high‐quality white paper | |
| Outcomes | Response period not specified | |
| Topic | Health: hysteroscopy | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Clarke 1998.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Study survivors resident in 3 health authority areas | |
| Comparisons | 1. 3 extra questions on current sources of income included 2. Extra questions not included 3. Extra questionnaire on cognitive functioning included 4. Extra questionnaire not included | |
| Outcomes | Response period not specified | |
| Topic | Health: Whitehall study | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; mean age: 77 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Clarke 2007.
| Study characteristics | ||
| Methods | A randomisation list was prepared by using a series of coin flips | |
| Data | Presidents and Deans of medical royal colleges and Deans of postgraduate medical and dental schools in the UK | |
| Comparisons | Sender's knighthood explicit on letter vs not | |
| Outcomes | Response after one reminder letter sent after 4 weeks | |
| Topic | Non‐health (institution's attitudes to critical appraisal and systematic reviews) | |
| Mode of Administration | Postal | |
| Notes | The letters were one and a half pages long, so that the signature and the 'Sir Iain Chalmers' or 'Iain Chalmers' appeared about halfway down the second page. IC signed each letter with his usual signature. The front page of the letter was on UK Cochrane Centre‐headed note paper, which did not contain IC's name. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | The series of coin flips to determine a randomisation group was written down with no knowledge of the intended recipients of the letters and in advance of the preparation of an alphabetic list of these people. |
| Allocation concealment? | Yes | The series of coin flips to determine a randomisation group was written down with no knowledge of the intended recipients of the letters and in advance of the preparation of an alphabetic list of these people. |
| Blinding of participants and personnel | Yes | The randomisation list was prepared by a personal assistant and then passed to MC who applied the random sequence to the alphabetic list. LH then prepared the letters in accordance with the allocation. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | No exclusions reported |
| Selective reporting | Yes | Response after one reminder letter sent after 4 weeks was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Clausen 1947.
| Study characteristics | ||
| Methods | Random allocation: systematic division | |
| Data | Non‐respondents to an earlier survey | |
| Comparisons | 1. Impersonal salutation; handwritten signature; franked outward envelope 2. Impersonal salutation; facsimile signature; franked outward envelope 3. Personal salutation; facsimile signature; franked outward envelope 4. Personal salutation; handwritten signature; franked outward envelope 5. Personal salutation; handwritten signature; airmail and special delivery outward envelope | |
| Outcomes | Response within 4 weeks | |
| Topic | Health: National Service Life Insurance (NSLI) | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Claycomb 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Marketing executives and managers representing a geographic cross‐section of the US | |
| Comparisons | Intervals between the original and 2 rounds of follow‐up mailings: 1. 3 days 2. 6 days 3. 9 days 4. 12 days 5. 15 days 6. 18 days 7. 21 days 8. 24 days 9. 27 days 10. 30 days 11. 33 days 12. 36 days 13. 39 days 14. 42 days 15. 45 days 16. 48 days 17. 51 days 18. 54 days 19. 57 days 20. 60 days | |
| Outcomes | Response after 3 mailings | |
| Topic | Non‐health: companies' customer relation practices | |
| Mode of Administration | Postal | |
| Notes | Dates of initial mailings randomised to prevent seasonal biases | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Cleopas 2006.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Adults discharged from teaching hospital system in Geneva | |
| Comparisons | 1. 2‐original response format (yes/no) 2. 3‐point similarity format (applies completely/in part/not at all) 3. 5‐point intensity format (completely true to completely false) 4. 5‐point frequency format (all the time to never) |
|
| Outcomes | Response period not specified | |
| Topic | Health: patient‐based outcome measure (Nottingham Health Profile) | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Coast 2006.
| Study characteristics | ||
| Methods | Random allocation: methods unspecified | |
| Data | Patients eligible for care by a GP with a special interest in dermatology | |
| Comparisons | Shorter questionnaire (11 pages) vs. longer (15 pages) | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (access to dermatology secondary care services) | |
| Mode of Administration | Postal | |
| Notes | Shorter questionnaire (11 pages); longer questionnaire (15 pages) Patients were sent a letter asking for their consent to participate in the research. On receipt of the signed consent forms, a study number was allocated to each respondent and a pre‐numbered envelope containing one of the two versions of the questionnaire was sent. Questionnaires were randomly selected. Up to 2 reminders were sent to non‐respondents. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: methods unspecified |
| Allocation concealment? | Unclear | Random allocation: methods unspecified |
| Blinding of participants and personnel | Yes | Randomised and placed in envelope by a member of research team not involved in subsequent allocation of study numbers and posting of questionnaire |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported in full |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cobanoglu 2001.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 300 hospitality professors randomly chosen from the Council on hotel, restaurant, and institutional education members with email addresses, US | |
| Comparisons | Postal vs. fax vs. web | |
| Outcomes | Surveys returned | |
| Topic | Non‐health (hospitality education) | |
| Mode of Administration | Postal, web and fax | |
| Notes | Questionnaire not described. A cover letter introducing the survey was personally addressed, with specific instructions on how to respond. For the mail group, personalised cover letters were printed on university letterhead using a mail merge program and folded with a printed survey and business reply envelope. The faxed version included a personalised cover letter, with a university letterhead logo embedded into the software, and a survey. For the web‐based survey, an email message was sent to the professors along with a cover letter and the website address. The respondents were informed that they could request a paper copy of the survey should they have problems accessing the survey online. A unique website address was created for each respondent with the help of a common gateway interface protocol. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Of the original 300 surveys, only six surveys came back as undelivered. One mail survey was returned as having gone to the wrong address; all the fax surveys went through successfully; and five of the email invitations were returned as undeliverable. |
| Selective reporting | Yes | One outcome: surveys returned fully reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cobanoglu 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Managers who are members of the American Management Association (AMA) | |
| Comparisons | 1. Luggage tag (LT) 2. Prize draw for a personal digital assistant (PDA) 3. Prize draw for both LT and PDA 4. Control |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | adequate |
Cochrane 2020.
| Study characteristics | ||
| Methods | Computer‐generated using Stata version 13.0 | |
| Data | OTIS study participants (aged 65 years or over, willing to receive a home visit from an OT, community dwelling, at risk of a fall in the next 12 months), UK | |
| Comparisons | Personalised SMS reminder vs standard SMS | |
| Outcomes | Proportion of questionnaires returned to York Trials Unit at four months post‐randomisation after one reminder letter | |
| Topic | Health (prevention of falls in older people) | |
| Mode of Administration | Postal with electronic prompts | |
| Notes | Questionnaire not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated using Stata version 13.0 |
| Allocation concealment? | Yes | Randomc allocation: computer‐generated using Stata version 13.0 |
| Blinding of participants and personnel | Yes | Blinding of personnel not described. Participants were not aware of their involvement within this SWAT; only to the OTIS trial group allocation. Study team members performing administrative, statistical or health economic roles were not blinded, but data entry staff were. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Delays in setting‐up the text messaging system meant no texts were sent prior to 7th December 2017. In total, 120 (29.8%) randomised participants were due texts before this date. These participants are therefore excluded from the analysis. |
| Selective reporting | Yes | Proportion of questionnaires returned to York Trials Unit at four months post‐randomisation after one reminder letter was reported for both arms of the trial. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cockayne 2005.
| Study characteristics | ||
| Methods | Random allocation | |
| Data | Community‐dwelling women aged over 70 years living in the York and Cumbria area | |
| Comparisons | 1. Offer of study results 2. Control |
|
| Outcomes | Response period not specified | |
| Topic | Health: calcium and vitamin D supplementation for fracture prevention | |
| Mode of Administration | Postal | |
| Notes | Independent researchers from the York Trials Unit randomised the eligible women. Administration of the questionnaire was not blind to group allocation. Age: Above 70 years; mainly females |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | adequate |
Cohen 2019.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (random number generator in Stata) | |
| Data | Authors and editors involved in online publishing totalling 2426 participants from 111 countries | |
| Comparisons | $100 gift card incentive vs. $2.50 altruistic donation to rotary club vs. no incentive | |
| Outcomes | Response after 1 reminder sent to non‐responders 10 days after the initial survey was sent | |
| Topic | Non‐health (author and editor attitudes regarding predatory publishing) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire not described. An automated survey invitation was sent to each email stating the incentive, as such participants were not blind. However, subjects were unaware there were different incentives for other invitees. Each email invitation was personalised with the individual's name in an automated fashion to increase the likelihood of individuals reading the email and completing the survey. 1 automated reminder sent to non‐responders 10 days after the initial survey was sent. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: subject randomised using a random number generator in Stata |
| Allocation concealment? | Yes | Random allocation: subject randomised using a random number generator in Stata |
| Blinding of participants and personnel | Yes | An automated survey invitation was sent to each email stating the incentive, as such participants were not blind. However, subjects were unaware there were different incentives for other invitees. Authors were blinded to group assignments while surveys were administered. Data analysis took place in a blinded fashion based on three groups of unknown incentives. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | 199 (8%) of email contact information resulted in a return to sender response, leaving a final 2227 participants. |
| Selective reporting | Yes | Response after 1 reminder reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Collins 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of the RAND adolescent/young adult panel study drawn from schools across the US | |
| Comparisons | 1. $20 cash with mailing 2. $20 cash promised on return of questionnaire 3. $25 cash promised on return of questionnaire | |
| Outcomes | Response within approximately 4 months | |
| Topic | Health: substance use, problem behaviour, predictors of risk behaviour, attitudes and beliefs | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Conner 2017.
| Study characteristics | ||
| Methods | Random allocation: using a random number generator | |
| Data | 13,803 participants aged 65+ recruited from 7 GPs in Northern England not participating in flu vaccine invitation scheme | |
| Comparisons | Post‐it note attached to the questionnaire with blue (imitation handwritten) message ('Please take a few minutes to complete this for us. Thank you!') vs. no post‐it note | |
| Outcomes | Response after reminders | |
| Topic | Health (influenza vaccination attitudes and intentions) | |
| Mode of Administration | Postal | |
| Notes | Letter and SAE with questionnaire and option to enter a £200 prize draw. Questionnaires included a code number to allow them to be matched to patient records. Materials were sent one month before the influenza vaccinations were available. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: using a random number generator |
| Allocation concealment? | Yes | Random allocation: using a random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Converse 2008.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1500 pre‐K through Grade 12 teachers awarded certification by the National Board for Professional Teaching Standards (NBPTS) in the states of Ohio and South Carolina (750 teachers from each state), US | |
| Comparisons | (a) Mail then email/Web follow‐up vs. (b) email/Web then mail follow‐up | |
| Outcomes | Postal‐postal pre‐notification (with unconditional $2), followed by questionnaire and SAE. Postal reminder, then a 2nd postal questionnaire and email with URL. Electronic‐postal pre‐notification (with unconditional $2), followed by email and questionnaire URL, email reminder followed by 2nd email reminder and postal questionnaire with SAE | |
| Topic | Non Health (voluntary evaluation for recognising accomplished educators) | |
| Mode of Administration | Postal and electronic | |
| Notes | 4 sections; 53 core items, 42 additional (branching); mixed format (Likert scale, yes/no, commentary, tick applicable); paper‐based version and web‐based to preserve appearance and content of paper The mail‐email/Web group received the following contacts: (a) a pre‐notice letter, addressed to the participant and sent via US mail, explaining that a survey would be arriving soon, along with a $2 bill as a token of appreciation; (b) a questionnaire, letter of instruction, and a pre‐addressed stamped envelope for return via US mail; (c) a stamped postcard reminder via US mail; (d) a second questionnaire in an envelope and with a letter similar to the initial questionnaire mailing; and (e) a special contact via email that directed the participant to the Web‐based questionnaire. The email/Web‚ mail group received the following contacts: (a) a pre‐notice letter, addressed to the participant and sent via US mail, explaining that a survey would be arriving soon, along with a $2 bill as a token of appreciation; (b) an email that directed the participant to the Web‐based questionnaire; (c) an email reminder; (d) a second email reminder; and (e) a special contact consisting of a US mail questionnaire that was identical to that sent as the initial mail‐mail/Web group questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Six individuals from the original sample were removed for these analyses: 4 individuals were not National Board Certified Teachers (NBCTs), 1 indicated he or she did not wish to participate, and 1 entered a duplicate ID number when responding by Web. The analyses were based on the remaining 1494 individuals. |
| Selective reporting | Yes | Responses after all contacts are reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cook 2016.
| Study characteristics | ||
| Methods | Computer‐generated (randomisation for both interventions was done by a research assistant using a random number generator in Microsoft Excel) | |
| Data | Licenced physicians in the United States | |
| Comparisons | Conditional non‐monetary incentive (book) vs no incentive; letter & email reminder vs postcard & email reminder vs email only reminder | |
| Outcomes | Response after 6 reminders | |
| Topic | Health (physician opinions regarding maintenance of certification and continuing medical education) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire not described (other than asking for opinions regarding maintenance of certification and continuing medical education) 7 days after the first email, we sent a reminder via paper mail to a subset of invitees using two formats. We timed this mailing to arrive at approximately the same time as the first email reminder. The invitees in one group received a personalised letter, printed on institution letterhead bonded paper and sealed in an envelope, asking them to complete the survey using the link they had received via email, or to contact the study investigators if they had not received or had deleted the email. A second group received a similar message via a personalised postcard that included the institution logo on both sides and was signed by one of the investigators. A third group received no paper reminder. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: randomisation using a random number generator (Microsoft Excel) |
| Allocation concealment? | Yes | Random allocation: randomisation using a random number generator (Microsoft Excel) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | We received notification that 682 emails were undeliverable, leaving 3966 potential respondents. |
| Selective reporting | Yes | Response after reminders was reported. |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Corcoran 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Masters level social workers | |
| Comparisons | 1. First‐class stamped return envelope
2. Reply permit return envelope Follow‐up postcard sent to all subjects 3 to 4 weeks after original mailing |
|
| Outcomes | Response period not specified | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Coryn 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | American Evaluation Association (AEA) Members | |
| Comparisons | No incentive vs. lottery (for $800 tablet) vs. non‐monetary incentive ($5 voucher) vs. philanthropic donation ($5 to the AEA Graduate Education Diversity Internship programme) | |
| Outcomes | Response after 4 reminders | |
| Topic | Non‐health (research on evaluation) | |
| Mode of Administration | Electronic (Internet surveys) | |
| Notes | 7 survey items; 4 closed‐response (one with matrix of 18 factors to be rated as to the extent to which they positively or negatively influence whether to complete a survey questionnaire). A pre‐survey notification email sent 1 week prior to survey. Weekly reminders (four in all) were sent to non‐responders. All communications sent to four groups were identical, except for the following: in lottery group: "As a token of our gratitude for participating in this study, you will be entered in a lottery to have an opportunity to receive a tablet (e.g. Apple iPad, Microsoft Surface) of your choice valued at up to US$800"; in token group: "As a token of our gratitude for participating in this study, you will receive a US$5 Amazon.com gift card"; philanthropic donation group: "As a token of our gratitude for participating in this study, we will donate US$5 to the AEA Graduate Education Diversity Internship (GEDI) program on your behalf"; control group: "This study can only be successful with the generous help of our fellow evaluators" (also communicated in the messages sent to the other three conditions). The fact that alternative incentives existed or were offered was intentionally withheld. The AEA member database used was de‐identified, thus preventing the use of potential respondents‚ names or titles in communications. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Blinding of personnel not described. Participants were blinded to intervention, the fact that alternative incentives existed or were offered was intentionally withheld. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 4 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cosgrove 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Professional social workers and volunteer community mediators | |
| Comparisons | Unconditional monetary ($2) incentive vs no incentive | |
| Outcomes | Response after 6 weeks (42 days) | |
| Topic | Health (factors associated with burnout and intention to leave amongst professional social workers and volunteer community mediators) | |
| Mode of Administration | Postal and electronic | |
| Notes | 116 item survey; serif font for paper and sans serif for web; fewer page items for web; cover page topical photo for both; 20 mins to complete The paper survey was mailed to all participants, along with a cover letter signed by all members of the research team explaining that participation was voluntary and anonymous, and an addressed and stamped envelope to return the completed survey. The incentive was included with the initial mailing of the survey, and was not contingent upon response. Fourteen days after the initial mailing, a follow‐up postcard was sent to all participants that thanked them for completing the survey, encouraged those who had not completed the survey to do so, and included a web address to complete the survey online. The surveys were printed on different colours of paper to distinguish the responses of participants who did and did not receive the incentive. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not reported. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Survey mailings were returned‐to‐sender for 20 VCMs and 10 LBSWs. |
| Selective reporting | Yes | Response after 6 weeks reported for both arms of the trial |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cotterill 2017.
| Study characteristics | ||
| Methods | Computer‐generated | |
| Data | Older people with long‐term conditions and social‐care needs participating in the Comprehensive Longitudinal Assessment of Salford Integrated Care (CLASSIC) cohort study | |
| Comparisons | Social pressure letter (letting the recipient know that their previous response had been noted and that future responses would be noted by the researcher) vs. letter without the social pressure text | |
| Outcomes | The primary outcome was retention in the host study, defined as return of both surveys, sent at 6 and 12 months after baseline. At each stage, non‐responders sent reminder letter after 3 weeks | |
| Topic | Health (brief measures of service experience, health and care outcomes and service utilisation) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Participants who did not return a questionnaire were sent a second copy with a reminder letter three weeks later. Participants in both groups were offered an incentive of a £10 voucher for completion of the first (baseline) questionnaire and £5 for completion of the third questionnaire, but no incentive was given for completion of the second questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Participants were blinded to their participation in the embedded study. They were not informed that other households were being sent differently worded letters: we expected that their actions might change if they knew what others received. The research team were not blinded to the intervention, but had minimal contact with trial participants. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response to both questionnaires reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cottrell 2015.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Fully qualified GPs who had managed a patient with chronic knee pain in the last six months | |
| Comparisons | Incentive (entry into a prize draw to win a £100 voucher vs. none) Length (eight sides of A4) vs. four sides of A4 | |
| Outcomes | Response period not specified | |
| Topic | Non‐health (attitudes, beliefs and reported clinical management of GPs regarding exercise for chronic knee pain) | |
| Mode of Administration | Postal | |
| Notes | The standard questionnaire was eight sides of A4 in length; contained 85 items. The questionnaire was presented in an A4 booklet format, created from folded and stapled A3 pages; the abbreviated questionnaire contained 36 items. The questionnaires were printed as booklets on white paper with the institution logo on the front cover. Initial mailing included a personalised combined cover letter and information sheet along with a questionnaire and SAE. Non‐responders sent reminder postcard after 2 weeks on A5 yellow card. Non‐responders further mailed a personalised reminder letter with 2nd questionnaire and SAE after a further 2 weeks (4 weeks) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not reported. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcome asessment used (counts of responses only) |
| Incomplete outcome data | Yes | 19 GPs did not meet inclusion criteria. |
| Selective reporting | Yes | Responses reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Coughlin 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Recent veterans who had been deployed in support of Operation Enduring Freedom/Operation Iraqi Freedom, US | |
| Comparisons | Unconditional $5 cheque incentive vs. conditional $5 cheque incentive vs. no incentive | |
| Outcomes | Response period not specified | |
| Topic | Topic not specified | |
| Mode of Administration | Postal and web | |
| Notes | 16‐page questionnaire. Packet contained 16‐page paper questionnaire, introductory letter signed by senior VA official, consent form and SAE. Also included URL. 2nd questionnaire sent 2 weeks later, and final questionnaire a further 4 weeks later. Reminder/thank you postcards sent one week after each mailing | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blind to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Received 137 refusals and learned of 2 deaths, bringing the number of contacted veterans to 783. |
| Selective reporting | Yes | Final response reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cox 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a southwestern city listed in the metropolitan telephone directory (US) | |
| Comparisons | 1. Personalised cover letter; follow‐up postcard after 3 days 2. Personalised cover letter; no follow‐up postcard 3. No personalised cover letter; follow‐up postcard after 3 days 4. No personalised cover letter; no follow‐up postcard | |
| Outcomes | Response within 16 days | |
| Topic | Non‐health: finance ‐ appraise consumer evaluations of financial institutions | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Crittenden 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Alumni members of a National Business School | |
| Comparisons | 1. White questionnaire 2. Yellow questionnaire 3. Questionnaire using letter‐quality printer 4. Questionnaire using Dot‐matrix printer |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: education | |
| Mode of Administration | Postal | |
| Notes | 2 x 2 factorial design | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Cunningham‐Burley 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Healthcare workers participating in a research study about slip‐resistant footwear in the NHS workplace | |
| Comparisons | Pen vs. no pen | |
| Outcomes | Response proportion after 4 months | |
| Topic | Health (slips in the workplace) | |
| Mode of Administration | Postal | |
| Notes | 10‐page questionnaire It may be that, in this group of participants, the pen failed to act as a facilitator or was not a sufficient incentive to return the questionnaire, given the fact that participants in the trial already received a free pair of shoes (although offer of shoes was not conditional on returning the questionnaire). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants were not aware of their involvement in this SWAT but due to the nature of the intervention participants and study team members could not be blinded to group allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | In total, 13 participants withdrew from the main SSHeW trial after they had been randomised into the SWAT but before being sent their follow‐up questionnaire. |
| Selective reporting | Yes | All response outcomes reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cureton 2021.
| Study characteristics | ||
| Methods | Computer‐generated randomisation list | |
| Data | Adults with rotator cuff disorder, UK | |
| Comparisons | Personalised vs standard text message reminder | |
| Outcomes | Response at 125 days | |
| Topic | Health (shoulder pain and function over 12 months after randomisation in the GRASP trial measured using the Shoulder Pain and Disability Index) | |
| Mode of Administration | Postal (electronic reminder option for non‐responders) | |
| Notes | Questionnaire not described The text message was sent to trial participants at the same time as their 6‐month follow‐up postal questionnaire was sent by the trial team; therefore, it would arrive a few days before the participant received their follow‐up questionnaire. Participants needed to have the use of a mobile telephone. Participants were willing to provide a mobile telephone number and consented for contact to be made by the trial team using this number. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Six participants were not sent the 6‐month follow‐up questionnaire; of these five withdrew from the host trial prior to the follow‐up time point, and one was missed from the mailout and SMS list in error. |
| Selective reporting | Yes | Response at 125 days reported for both arms |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Cycyota 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Businesses from the state sales and use of licence records in the southwestern region of US | |
| Comparisons | 1. US $1 bill 2. No incentive 3. Advance notice 4. No advance notice 5. Personalised salutation 6. No personalised salutation 7. Telephone follow‐up 8. No telephone follow‐up |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: employment | |
| Mode of Administration | Postal | |
| Notes | 2 X 2 X 2 X 2 X 2 fully crossed factorial design; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Danko 2019.
| Study characteristics | ||
| Methods | Computer‐generated random allocation sequence in R | |
| Data | Contact authors of all included studies (published studies on diabetes quality improvement interventions) in a systematic review who had not responded to initial email requests for information (international) | |
| Comparisons | Telephone reminder vs repeat email reminders only for non‐responders. | |
| Outcomes | Primary outcome was the response proportion, within 3 weeks, defined as the number of authors who completed the survey divided by the total number of authors assigned to the intervention. Tel intervention: authors called up to three times by telephone to request they complete online survey, and following up via email with the survey link and study PDF. Email intervention: up to three additional email requests (one request per week) to complete the survey. Emails included the survey link and study PDF. | |
| Topic | Health: diabetes | |
| Mode of Administration | Web‐based survey | |
| Notes | Questionnaire not described, but assumed under 20 questions on: study intervention components, populations, and settings Web‐based survey sent once a week via email to corresponding authors until they responded, requested not to be contacted further, or completed a maximum of three contact attempts. Emails to contact authors were sent from the email address of a senior investigator on the research team (J.M.G.). Provided an incentive: authors who completed the survey were entered in a draw for one of five $100 (CAD) gift certificates. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Computer‐generated random allocation sequence in R |
| Allocation concealment? | Yes | Computer‐generated random allocation sequence in R |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Deehan 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | GPs who did not respond to 2 mailings of a questionnaire (UK) | |
| Comparisons | Third mailing:
1. No incentive
2. £5 charity donation
3. £10 charity donation
4. £5 payment
5. £10 payment Fourth mailing to non‐responders in control group of third mailing: 1. £5 payment 2. £10 payment |
|
| Outcomes | Response period not specified | |
| Topic | Health: information on clinical work with alcohol‐misusing patients | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Del Valle 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of the American Association of Neurologists who did not respond to 2 earlier mailings | |
| Comparisons | 1. Questionnaire sent by certified mail with return receipt request postcard 2. Questionnaire sent by first‐class mail | |
| Outcomes | Response period not specified | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Delnevo 2004.
| Study characteristics | ||
| Methods | Random allocation: using a statistical software package | |
| Data | New Jersey internists, general practitioners, family physicians, paediatricians, and obstetricians and gynaecologists | |
| Comparisons | 1. Up‐front $25 gift card 2. Promised $25 gift card |
|
| Outcomes | Response period not specified | |
| Topic | Health: smoking cessation ‐ attitudes and practice | |
| Mode of Administration | Postal | |
| Notes | The investigators were not blinded to the treatment allocation ‐ confirmed by the author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Delnevo 2021.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Practising physicians, US | |
| Comparisons | Postal invitation to Web survey vs. postal survey | |
| Outcomes | Response after 2 months | |
| Topic | Health (physicians' attitudes and beliefs regarding tobacco use, smoking cessation and electronic cigarettes) | |
| Mode of Administration | Postal & electronic | |
| Notes | Questionnaire not described 1st mailing ‐ cover letter, $25 gift card (coffee chain), paper survey for mail mode/web‐push received URL in cover letter. Reminder postcard after 1 week to non‐respondents, 3rd mailing as 1st, and 4th and final mailing to non‐responders included URL and paper questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only) |
| Incomplete outcome data | Yes | 158 cases were determined to be ineligible (i.e. death, retirement, no active medical license in state, not board certified, not providing outpatient care). More ineligible cases were identified in the web‐push condition (83 vs. 75). |
| Selective reporting | Yes | Response after 2 months reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Denton 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Graduates from the Department of Educational Curriculum and Instruction at a large university in the southwest (US) | |
| Comparisons | 1. No incentive 2. Newsletter 3. $0.25 4. $0.25 and newsletter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: education | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Denton 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Experiments 1 and 2: graduates from the Department of Educational Curriculum and Instruction at a large university in the south‐west (US) | |
| Comparisons | Experiment 1:
1. No incentive
2. Newsletter
3. $0.25
4. $0.25 and newsletter Experiment 2: 1. No incentive 2. $0.25 3. $0.50 4. $1 5. Raffle |
|
| Outcomes | Experiment 2: response within 2 months | |
| Topic | Non‐health: classroom teachers pedagogical knowledge and skills | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Deutskens 2004a.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | Participants of the multi‐client attitude and usage study in the Netherlands | |
| Comparisons | 1. 2 euros vouchers for an online book and CD store 2. 5 euros vouchers for an online book and CD store 3. Lotteries to win vouchers worth 25 euros 4. Lotteries to win vouchers worth 50 euros 5. Charity donation of 500 euros to either World Wide Fund for Nature (WWF), Amnesty International, or a Cancer Association 6. Short version of the questionnaire 7. Long version of the questionnaire 8. Visual presentation of response categories 9. Textual presentation of response categories 10. Early follow‐up (after 1 week) 11. Late follow‐up (after 2 weeks) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing | |
| Mode of Administration | Electronic: online survey | |
| Notes | 3 X 2 X 2 X 2 factorial design Method of allocation ascertained through contact with author Age: Mostly 35‐49; mainly males |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Deutskens 2004b.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | University students | |
| Comparisons | 1. Lottery to win 1 out of 10 vouchers of 25 euros 2. Lottery to win 1 out of 5 vouchers of 50 euros 3. Lottery to win a DVD player |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: education | |
| Mode of Administration | Electronic: online | |
| Notes | Method of allocation ascertained through contact with author; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A: adequate |
Dillman 1974a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A group of Washington State University alumni | |
| Comparisons | 1. Personalised cover letter 2. Non‐personalised cover letter | |
| Outcomes | Response after 4 mailings | |
| Topic | Non‐health: feelings and concerns about Washington State University | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained to be random through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dillman 1974b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A systematic sample of people listed in the phone directories of Washington state, USA | |
| Comparisons | 1. No pre‐contact 2. Telephone pre‐contact | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: feelings and concerns about Washington State University | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained to be random through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dillman 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Housing units identified by the census bureau's address control file | |
| Comparisons | 1. 1990 short form (control) questionnaire 2. Booklet 3. Micro form 4. Micro form requesting SSN 5. Roster form | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: census | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dillman 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | National probability sample of households in the USA | |
| Comparisons | 1. Control group 2. Benefit appeal on envelope and insert; strong confidentiality assurance 3. Benefit appeal on envelope and insert; standard confidentiality assurance 4. Mandatory appeal on envelope and insert; strong confidentiality assurance 5. Mandatory appeal on envelope and insert; standard confidentiality assurance 6. Mandatory appeal on envelope only; no confidentiality assurance | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: census | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | D ‐ not used |
Dinglas 2015.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated random numbers | |
| Data | Acute lung injury survivors who were enrolled in randomised trials of novel interventional therapies funded by the National Heart, Lung, and Blood Institute (NHLBI) ARDS Network, US | |
| Comparisons | Personalised, stamped envelopes vs. typed, franked envelopes | |
| Outcomes | Response after 12 weeks (maximum of 4 biweekly mailings and 4 weekly phone calls) | |
| Topic | Health (outcomes in acute lung injury survivors) | |
| Mode of Administration | Postal | |
| Notes | One‐page health insurance survey Participants were contacted using a multi‐step, structured protocol starting with mailed letters and then telephone calls, as needed for non‐responders to mailings. Participants were mailed the insurance survey every 2 weeks until the survey was completed or the participant was sent a total of 4 mailings. For these mailings, trial participants were randomised to receive either a personal format letter in which their mailing address and the return address were handwritten and a traditional stamp was stamped using the envelope versus a business format letter in which the addresses were typed and the postage was affixed by a commercial stamp‐machine. In all other respects, the envelopes were identical (i.e. 9 x 12‐inch manila envelopes) and included an identical cover letter, insurance survey, and SAE. Starting 20 days after the end of the mail trial, a telephone trial was initiated. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Randomisation was performed by a statistician using computer‐generated random numbers. |
| Allocation concealment? | Yes | Randomisation was performed by a statistician using computer‐generated random numbers. |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Outcomes reported in full including attrition and exclusions |
| Selective reporting | Yes | Responses after 4 contacts reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dirmaier 2007.
| Study characteristics | ||
| Methods | Random allocation: using a computer‐assisted algorithm | |
| Data | Patients admitted for psychotherapeutic treatment | |
| Comparisons | 1. Long questionnaire 2. Short questionnaire 3. 5 German Mark bill 4. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: mental health outcome and treatment research | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly 40‐59; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: Patients were randomised using a computer‐assisted algorithm. |
| Allocation concealment? | Yes | Random allocation: Patients were randomised using a computer‐assisted algorithm. |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after one reminder at 4 weeks reported fully |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dodd 1987.
| Study characteristics | ||
| Methods | Random allocation: using a table of random numbers | |
| Data | Women employed full‐time in various civil servant positions at a university (US) | |
| Comparisons | 1. Hand‐signed, professor status, female author 2. Hand‐signed, student status, female author 3. Hand‐signed, professor status, male author 4. Hand‐signed, student status, male author 5. Photocopied signature, professor status, female author 6. Photocopied signature, student status, female author 7. Photocopied signature, professor status, male author 8. Photocopied signature, student status, male author | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Allocation concealment not described; mean age: 42 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doerfling 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Members of the Canadian Association of Retired Persons. | |
| Comparisons | $1000 lottery incentive vs. no incentive | |
| Outcomes | Outcomes: clicked on hyperlink and completed Survey (responses after two weeks with 2 reminder emails) | |
| Topic | Health (survey of physical activity and joint health) | |
| Mode of Administration | Electronic | |
| Notes | 33 questions on demographics, socioeconomic status, physical activity (sport, occupational and domestic), diagnosis of arthritis, previous and current knee pain, and computer usage Emails contained a personal letter from principal investigator, a short description of the study, a contact email address for questions. Half of the subjects were randomly allocated to receive an email that contained the incentive, while the other half received a message with no financial incentive. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Responses after two weeks with 2 reminder emails reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dommeyer 1980a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in the Cincinnati telephone directory (US) | |
| Comparisons | 1. Questionnaire with low threat follow‐up
2. Questionnaire with low‐moderate follow‐up
3. Questionnaire with low‐moderate follow‐up (different to above)
4. Questionnaire with moderate follow‐up
5. Questionnaire with follow‐up with moderate appeal
6. Questionnaire with prepaid incentive of 25 cents in follow‐up
7. Personally asked to compare the relative noxiousness of the threat of appeals sent to groups 1‐4 Non‐respondents to the initial mailings were followed up |
|
| Outcomes | Response within 31 days | |
| Topic | Non‐health: attitudes towards questionnaire, socio‐demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 1980b.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Individuals listed in the Cincinnati telephone directory (US) | |
| Comparisons | 1. Questionnaire with ID number typed on lower righthand corner of last page 2. As above, with words: 'Please do not remove identifying code number' typed next to the ID number | |
| Outcomes | Response within 13 days | |
| Topic | Non‐health: attitudes towards questionnaire, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Dommeyer 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Undergraduate business students (US) | |
| Comparisons | 1. Interesting questionnaire; no summary of results offered 2. Interesting questionnaire; results summary offered 3. Uninteresting questionnaire; no summary of results offered 4. Uninteresting questionnaire; results summary offered | |
| Outcomes | — | |
| Topic | Non‐health: finance ‐ tax survey; Mind Inventory Catalogue | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 1987.
| Study characteristics | ||
| Methods | Random allocation using alternation | |
| Data | Telephone owners in Cincinnati | |
| Comparisons | 1. Negative appeal mention of follow‐up 2. Usual mail 3. Prepaid incentive of 25 cents each |
|
| Outcomes | Response to be received by 28th June | |
| Topic | Non‐health: attitudes and familiarity towards mail; education, employment | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Dommeyer 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in the Chicago and Phoenix telephone directory | |
| Comparisons | Different postscripts used in letter depending on intervention:
1. No incentive
2. 25 cent coin
3. 25 cent cheque
4. 25 cent money order
5. Early bird ‐ get a share in an incentive ($25) if send questionnaire back quickly
6. Sweepstake (entered into sweepstake to win $25 if return questionnaire by deadline) All participants sent cover letter and questionnaire in window envelope |
|
| Outcomes | — | |
| Topic | Non‐health: product tampering and Morality Conscience Guilt Scale | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Personal computer owners, manufacturers and retailers | |
| Comparisons | 1. Cover letter stressed importance of response and emphasised that respondents' names would never be placed on the questionnaire (control group). 2. Second paragraph offered respondents a summary of the results. 3. Standard cover letter. Offer of a copy of the results made in a separate 'lift' letter | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: knowledge and attitudes towards computer counterfeiting | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Californian residents who were entitled to a refund | |
| Comparisons | 1. Teaser printed on envelope 2. No teaser on envelope | |
| Outcomes | Response within 2 weeks | |
| Topic | Non‐health: finance ‐ awareness and attitudes towards insurance refunds | |
| Mode of Administration | Postal | |
| Notes | "A teaser is typically a short question printed on the outer envelope that is designed to lure the recipient into the examining [of] the content of the envelope". | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed in a telephone directory (Los Angeles, USA) | |
| Comparisons | 1. Photograph of an 'attractive' researcher printed on cover letter 2. No photo printed on cover letter | |
| Outcomes | — | |
| Topic | Non‐health: attitudes towards music censorship and warning stickers on music albums | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dommeyer 2004.
| Study characteristics | ||
| Methods | Random allocation: using randomised incomplete block design | |
| Data | Undergraduate business major students at California State University | |
| Comparisons | 1. Grade incentive 2. In‐class demonstration of the web survey 3. Early grade feedback 4. Control |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: education | |
| Mode of Administration | Electronic: online survey | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Donaldson 1999.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians randomly selected from a list of US physicians actively caring for at least 1 transplant patient | |
| Comparisons | 1. $5 check with initial mailing; no follow‐up call 2. $5 check with initial mailing; follow‐up call to non‐responders 4 weeks after initial mailing 3. No incentive; no follow‐up call 4. No incentive; follow‐up call to non‐responders 4 weeks after initial mailing | |
| Outcomes | — | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | Mean age: 47 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doob 1971a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a phone book (Toronto and Ontario, Canada) | |
| Comparisons | 1. No reactance (letter written normally); no incentive 2. No reactance; dime incentive 3. Reactance (request written to make participants feel an attempt was being made to limit their freedom); no money 4. Reactance; dime incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Health: knowledge that smoking causes cancer | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doob 1971b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a phone book (Toronto and Ontario, Canada) | |
| Comparisons | 1. No reactance (letter written normally); no incentive 2. No reactance; dime incentive 3. Reactance (request written to make participants feel an attempt was being made to limit their freedom); no money 4. Reactance; dime incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Health: knowledge that smoking causes cancer | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doob 1971c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a phone book (Toronto and Ontario, Canada) | |
| Comparisons | 1. No reactance (letter written normally); no incentive 2. No reactance; 20 cents incentive 3. Reactance (request written to make participants feel an attempt was being made to limit their freedom); no money 4. Reactance; 20 cents incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Health: knowledge that smoking causes cancer | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doob 1973.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a telephone directory (Canada) | |
| Comparisons | 1. 20 cents incentive
2. 5 cents incentive
3. No incentive 1. University sponsor 2. Industrial sponsor |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: automobile ownership, duration spent on watching TV | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Doody 2003a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | US radiologist technologists who had not responded to 2 earlier mailings of a questionnaire | |
| Comparisons | 1. US first‐class mail; no incentive 2. US first‐class mail; $1 bill 3. US first‐class mail; $2 bill 4. US first‐class mail; $2 check 5. US first‐class mail; $5 check | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | All subjects received a pre‐notification letter; age: mostly 40‐49 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Doody 2003b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | US radiologist technologists who had not responded to 2 earlier mailings of a questionnaire | |
| Comparisons | 1. Federal express; no incentive 2. Federal express; $1 bill 3. Federal express; $2 bill 4. Federal express; $2 check | |
| Outcomes | Response period not specified | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | Age: mostly 40‐49 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dorman 1997.
| Study characteristics | ||
| Methods | Random allocation: using an allocation code generated by an adaptive randomisation algorithm | |
| Data | Patients who had been entered into the International stroke trial between 2 March 1993 and 31 May 1995 | |
| Comparisons | 1. Questionnaire incorporating the EuroQoL
2. Questionnaire incorporating the SF‐36 Questionnaires were identical in all respects other than the nature of the HRQoL instrument. EuroQoL has 7 questions, SF‐36 has 36. Both had same number of pages, but the first questionnaire had fewer questions. Reminders sent to non‐responders after 2 weeks |
|
| Outcomes | — | |
| Topic | Health: SF‐36, EuroQoL | |
| Mode of Administration | Postal | |
| Notes | The randomisation algorithm used aimed to balance the 2 groups for age, sex, stroke syndrome and the time from stroke onset to follow‐up | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Downes‐Le Guin 2002.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | IT managers in US businesses | |
| Comparisons | 1. Unconditional Amazon gift certificate ($15) 2. Unconditional Amazon gift certificate ($25) 3. Conditional Amazon gift certificate ($15) 4. Conditional Amazon gift certificate ($25) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Drummond 2008.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | Primary care physicians working in Ireland | |
| Comparisons | 1. Pre‐contact via mail 2. No pre‐contact 3. Questionnaire order: version 1, demographics first 4. Questionnaire order: version 2, topic‐specific questions first (prostate‐specific antigen testing) |
|
| Outcomes | Response period not specified | |
| Topic | Health: views and practices about prostate‐specific testing (PSA) | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated random numbers |
| Allocation concealment? | Yes | Random allocation: computer‐generated random numbers |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | During the trial, 132 of the 1599 samples were found to be ineligible and were excluded; 65 had retired, 38 had died, and 29 did not see appropriate patients. |
| Selective reporting | Yes | Response after 2 reminders (8 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Drummond 2014.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1650 Irish general practitioners | |
| Comparisons | Unconditional monetary incentive (5 EU) vs. no incentive; Conditional non‐monetary incentive (1 in 50 chance for 300 EU) vs. no incentive |
|
| Outcomes | Response after 2 reminders | |
| Topic | Health (primary care physicians' practice and costs in relation to prostate‐specific antigen (PSA) testing) | |
| Mode of Administration | Postal | |
| Notes | 20‐item survey over 2 pages With their questionnaire, primary care physicians received: (1) EUR 5 and a cover letter stating that this was a token of appreciation (cash arm); (2) a cover letter stating that they would be entered into a draw for one of three EUR 300 vouchers, with a 1‐in‐50 chance of winning, on return of completed questionnaire (prize arm); or (3) a cover letter (no‐incentive arm). Comparison of unconditional vs. unconditional incentives is confounded by amount. Primary care physicians received personalised letters on university‐headed paper and questionnaires were printed with coloured ink on coloured paper. Prepaid preaddressed envelopes for questionnaire return were included with each mailing. Up to two written reminders were sent to non‐responders at approximately two‐weekly intervals with another questionnaire in the second reminder. Both reminder letters to the prize arm mentioned the incentive. No reference to the EUR 5 was made in reminder letters to the cash arm. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | After questionnaire dispatch, PCPs who died, retired, relocated (and no forwarding address was available), and those without male patients aged 40 years and older (n = 5223) were deemed ineligible and removed from the denominator of the relevant arm. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Duffy 2001.
| Study characteristics | ||
| Methods | Random allocation: twin numbered 01 in each pair received single stamp; the other received the intervention | |
| Data | Twins who are volunteer members of the Australian NHMRC Twin Registry | |
| Comparisons | 1. Single stamp on enclosed return envelope 2. Multiple stamps (3‐5) on enclosed return envelope | |
| Outcomes | Response period not specified | |
| Topic | Health: asthma, psoriasis | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Duhan 1990.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Industrial marketing executives | |
| Comparisons | 1. Pre‐notification 2. No prior notification | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Dunn 2003.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | Patients aged 30‐59 years with back pain in the UK | |
| Comparisons | 1. Traditional questionnaire ‐ generic questionnaires first followed by disease‐specific ones 2. Chronological questionnaire ‐ individual questions arranged in sections according to the period of time that they ask about |
|
| Outcomes | Response period not specified | |
| Topic | Health: patient‐based outcome measures ‐ chronic pain grade, SF‐36, Hospital & Anxiety Scale, Roland‐Morris Disability Questionnaire | |
| Mode of Administration | Postal | |
| Notes | Mean age: 45 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Dykema 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified. | |
| Data | Doctors of internal medicine from the American Medical Association Masterfilm, US | |
| Comparisons | Pre‐notification letter with $2 incentive vs. pre‐notification letter only Pre‐notification letter vs. none Non‐monetary incentive ($200 lottery, conditional $50 or $100 cheque) vs. no incentive |
|
| Outcomes | Response after 4 email reminders and a postal letter with URL | |
| Topic | Health: physicians understanding of human genetic variation | |
| Mode of Administration | Electronic (Web survey) | |
| Notes | 80‐item survey. Study procedures included up to seven points of contact with sample members. First, selected respondents were mailed a postal pre‐notification letter that used study‐specific stationery, bore sponsors' names, described the study's purpose, and noted respondents would be sent an email invitation to complete the web survey. A $2 bill for respondents assigned to the prepaid group. Approximately 1 week later, all respondents were sent an email invitation to participate that included a hot‐linked (clickable) URL. For the third to sixth contacts, email reminders containing the hotlinked URL were sent. For the seventh contact, non‐responding physicians were sent a postal letter that included a manual URL, which the physician could type into a browser. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dykema 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Non‐Hispanic African‐American mothers participating in the Pregnancy Risk Assessment Monitoring System, US | |
| Comparisons | Monetary incentive ($5) vs. non‐monetary ($6 diaper coupon) Monetary incentive ($5) vs. none Non‐monetary incentive ($6 diaper coupon) vs. none |
|
| Outcomes | Response after 3 postal reminders and one phone reminder | |
| Topic | Health (attitudes and behaviours of mothers before, during, and after pregnancy) | |
| Mode of Administration | Postal | |
| Notes | An introductory pre‐notification letter was mailed to each woman in the sample 24 months after the infants' birth. The initial PRAMS packet was mailed a few days later. The packet contained several items including a 13‐page questionnaire, cover letter, consent form, FAQ, and token inserts (a calendar, door hanger, brochure for the Wisconsin Maternal and Child Health Hotline, post‐it notes, and bath thermometer). Following the initial mailing, mothers were sent a note thanking those who had participated and reminding those who had not. Non‐responders received up to two additional mailings. After three mailings, we attempted to contact the remaining non‐respondents by telephone to complete the interview by phone. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Telephone interviewers who called non‐respondents to the mail survey were blind to the experimental conditions, and respondents were not reminded of the incentive in the phone phase. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 postal reminders and one phone reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dykema 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | University faculty members from departments in biology, chemistry, mathematics, physics, and physiology at the University of Wisconsin‚ US | |
| Comparisons | Mailed invitation letter (with URL); vs. emailed invitation (clickable URL) Unconditional $2 cash incentive vs. no incentive |
|
| Outcomes | Responses after initial invitation and responses after 2 email reminders | |
| Topic | Non‐health (attitudes and beliefs about the challenges and constraints faced when teaching in science, technology, engineering and mathematics (STEM) fields) | |
| Mode of Administration | Electronic (Web survey) | |
| Notes | 151 questions, although the number of questions answered by any one respondent varied considerably due to skip patterns The letter was printed on study‐specific stationery, described the study‚ purpose and funder, and included a URL and authentication credentials, which the sample member could manually type into a browser in order to access the survey instrument. The mailed invitation letters in the incentive and no incentive groups were identical except that the former made reference to the incentive using the text, 'Please accept the enclosed $2.00 as our way of thanking you in advance for your participation'. The mailed invitation was sent first class via the U.S. Postal Service to sample members‚ postal addresses on campus. Email invitations were sent 5 days after the mailed invitations. They contained a clickable URL with embedded authentication credentials as well as a description of the study and funder. The email's subject line referenced the content of the survey (e.g. 'Culture, Cognition and Evaluation of STEM Higher Education Reform Survey') All sample members had campus postal and email addresses on file. The questionnaire could only be completed over the Internet. The survey was administered by the University of Wisconsin Survey Center from December 2009 to January 2010 on behalf of the University of Wisconsin‚ Center for Education Research. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dykema 2015a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2608 household addresses randomly selected from 2 counties in Wisconsin (participants were aged between 18 and 74 years), US | |
| Comparisons | Unconditional $2 pre‐incentive vs. $5 Message on envelope ('Thank You! A cash gift is enclosed') vs. no message Unconditional $2 on follow‐up vs. no incentive | |
| Outcomes | Response after 2 reminders over 2 months | |
| Topic | Health (health‐ and community‐related topics, including health behaviours, food purchasing routines, and community satisfaction) | |
| Mode of Administration | Postal | |
| Notes | 124 items on 12 pages in La Crosse county; 164 items on 18 pages in Wood county Sampled households received up to three contacts by mail. The initial packet contained a cover letter bearing the county seal, cash incentive, questionnaire, and self‐addressed first‐class stamped return envelope. Materials were sent in a 10" x 13" envelope with a first‐class stamp. Approximately a week after the initial mailing, all households received a reminder postcard. Approximately one month after the initial mailing, all non‐responders were sent an additional packet containing a cover letter, second incentive (if relevant), questionnaire, and return envelope. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Participants not eligible reported |
| Selective reporting | Yes | Response after 2 reminders over 2 months reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dykema 2015b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2608 household addresses randomly selected from 2 counties in Wisconsin (participants were aged between 18 and 74 years), US | |
| Comparisons | Envelope with no message vs. monetary incentive message vs. health message follow‐up prepaid $0 incentive vs. follow‐up prepaid $5 | |
| Outcomes | Response after 2 reminders over 2 months | |
| Topic | Health (health‐ and community‐related topics, including health behaviours, food purchasing routines, and community satisfaction) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires varied between the counties (124 items on 12 pages in La Crosse versus 164 items on 18 pages in Wood). All study materials were written and completed in English. Sampled households received up to three contacts by mail. The initial packet contained a cover letter bearing the county seal, cash incentive, questionnaire, and self‐addressed first‐class stamped return envelope. Materials were sent in a 10" x 13" envelope with a first‐class stamp. Approximately a week after the initial mailing, all households received a reminder postcard. Approximately one month after the initial mailing, all non‐responders were sent an additional packet containing a cover letter, second incentive (if relevant), questionnaire, and return envelope. The target population for Dykema 2015b was identical to Dykema 2015a: adults (18–74 years) residing in the same two targeted counties. The design of Dykema 2015b mirrored Dykema 2015a. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Participants not eligible reported |
| Selective reporting | Yes | Response after 2 reminders over 2 months reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Dykema 2021.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1500 practising paediatricians, US | |
| Comparisons | Unconditional $5 monetary incentive in first mailing vs. unconditional $10 monetary incentive in first mailing | |
| Outcomes | Response after 3 mailings over 3 months | |
| Topic | Health (paediatricians' attitudes, training needs, and practices regarding advising parents about child discipline and related parenting issues) | |
| Mode of Administration | Postal | |
| Notes | 84 items formatted on 8 pages. Sampled physicians received up to 4 contacts by mail. The initial mailing packet contained a cover letter, cash incentive, questionnaire, and a self‐addressed first‐class‐stamped return envelope. Materials were sent in a 10" x 13" envelope with a first‐class stamp. Approximately a week after the initial mailing, a reminder postcard sent. 1 month after the initial mailing, non‐responders sent a second mailing containing a cover letter, second incentive (if relevant), questionnaire, and return envelope. Approximately 3 weeks later, all remaining non‐responders were sent a final mailing packet that contained a cover letter, questionnaire, and return envelope. The field period extended from March to June 2016. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Unclear | No grounds for concern about other sources of bias from reading the study report |
Eaker 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Men and women living in Sweden in 1995 | |
| Comparisons | 1. Preliminary notification (PN); long questionnaire (LQ); mention of telephone contact (MTC)
2. PN; short questionnaire (SQ); MTC
3. PN; LQ; no MTC
4. PN; SQ; no MTC
5. No PN; LQ; MTC
6. No PN; SQ; no MTC
7. No PN; LQ; no MTC
8. No PN; SQ; no MTC Reminders sent to all after 1 week |
|
| Outcomes | Response within 75 days | |
| Topic | Health: medical history, physical activity, eating and drinking habits, reproductive history | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly above 45 years; equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Easton 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Paediatricians listed in the American Academy of Paediatrics Directory | |
| Comparisons | 1. Information booklet 2. $1 incentive | |
| Outcomes | Response period not specified | |
| Topic | Health: counselling about sun protection | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Edelman 2013.
| Study characteristics | ||
| Methods | Random allocation: online random number generator | |
| Data | Rural older (> 65 yrs) adults participating in a rural county home‐delivered meals programme, US | |
| Comparisons | Hand‐delivered by someone known vs. by Postal Service delivery | |
| Outcomes | Response after one reminder | |
| Topic | Health (injury risk for older adults) | |
| Mode of Administration | Postal/electronic | |
| Notes | The survey was designed with older adults in mind and incorporated some strategies to improve recruitment, including a sans serif typeface, a minimum font size of 12 points, double‐spacing, and white‐space allowances (National Institute on Aging, 2012). The survey contained 48 closed‐ended items and one item asking if respondents would rather answer a paper‐ or Web‐based survey. Letter printed on the principal investigator's official stationery and signed by the investigator, the questionnaire, and an SAE. Pre‐notification letters, followed by the survey 5 days later, and a reminder/thank‐you postcard 6 days after the survey. Each questionnaire was numbered according to whether it was hand or postal delivered. The return date was recorded for each survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: online random number generator |
| Allocation concealment? | Yes | Random allocation: online random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Edwards 2001.
| Study characteristics | ||
| Methods | Random allocation: central randomisation | |
| Data | Head injured adults in the CRASH trial (UK) | |
| Comparisons | 1. 1‐page questionnaire 2. 3‐page questionnaire | |
| Outcomes | Response within 3 months | |
| Topic | Health: disability after traumatic brain injury | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Edwards 2009.
| Study characteristics | ||
| Methods | Random allocation: computerised random‐number table | |
| Data | 1587 American Indian adults living in the southwestern US aged 18 and over who completed a baseline study visit as part of Navajo EARTH cohort | |
| Comparisons | Long (18 pages) vs short (3 pages) follow‐up postal questionnaire | |
| Outcomes | Response after one month (2 reminders) | |
| Topic | Health (medical history and physical activity) | |
| Mode of Administration | Postal | |
| Notes | Each questionnaire included a one‐page medical history questionnaire asking the participant to update his or her health information. The short questionnaire also included the short format International Physical Activity Questionnaire making it 3 pages in length, while the long questionnaire included a 17‐page physical activity log developed for the Navajo EARTH Study physical activity validation study, making it 18 pages in length. Both follow‐up questionnaires were in English only. Cover letter and SAE were included with the questionnaire mailout packet, a postcard reminder was sent after the first mailing, a letter and second questionnaire were mailed to all non‐respondents approximately 1 month after the postcard was sent. The recommended mailing intervals were adjusted due to the potential delays in picking up mail. We included a $5 incentive with the first mailing and a sharpened pencil with each mailing. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computerised random‐number table |
| Allocation concealment? | Yes | Random allocation: computerised random‐number table |
| Blinding of participants and personnel | No | The study design did not allow for staff and participants to be blinded. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after one month (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Edwards 2016a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients with depression and raised risk of cardiovascular disease | |
| Comparisons | Pre‐calling participants vs. no pre‐call | |
| Outcomes | Response after 3 reminders (6 weeks) | |
| Topic | Health (depression ‐ PHQ‐9) | |
| Mode of Administration | Postal/electronic | |
| Notes | Questionnaires included the same questions (e.g. depression (PHQ‐9), anxiety, treatment satisfaction, health service use), and took approximately 40 minutes to complete. A few days before the 4‐month follow‐up was due, participants were automatically sent the questionnaire in the same format (online or postal) that they had chosen to complete at baseline. For those who did not respond promptly, a standard procedure was followed in terms of sending out reminders for all follow‐ups. This involved: sending an email reminder; phoning the participant; posting a questionnaire (a second copy was posted for those who were completing the paper version); posting just the primary outcome questions (the PHQ‐9); finally, phoning participants to ask them to post back the PHQ‐9 or offering to complete it over the phone. After this final phone reminder was completed, no further attempts were made to collect data for that follow‐up time point. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders (6 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Edwards 2016b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients with depression and raised risk of cardiovascular disease | |
| Comparisons | Colour photograph of the research team vs. no photo | |
| Outcomes | Response after 3 reminders (6 weeks) | |
| Topic | Health (depression ‐ PHQ‐9) | |
| Mode of Administration | Postal/electronic | |
| Notes | Questionnaires included the same questions (e.g. depression (PHQ‐9), anxiety, treatment satisfaction, health service use), and took approximately 40 minutes to complete. A few days before the 4‐month follow‐up was due, participants were automatically sent the questionnaire in the same format (online or postal) that they had chosen to complete at baseline. For those who did not respond promptly, a standard procedure was followed in terms of sending out reminders for all follow‐ups. This involved: sending an email reminder; phoning the participant; posting a questionnaire (a second copy was posted for those who were completing the paper version); posting just the primary outcome questions (the PHQ‐9); finally, phoning participants to ask them to post back the PHQ‐9 or offering to complete it over the phone. After this final phone reminder was completed, no further attempts were made to collect data for that follow‐up time point. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders (6 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Edwards 2016c.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients with depression and raised risk of cardiovascular disease | |
| Comparisons | 'ACTION REQUIRED' subject in initial email reminder vs. 'Questionnaire reminder' in email subject | |
| Outcomes | Response after 3 reminders (6 weeks) | |
| Topic | Health (depression ‐ PHQ‐9) | |
| Mode of Administration | Postal/electronic | |
| Notes | Questionnaires included the same questions (e.g. depression (PHQ‐9), anxiety, treatment satisfaction, health service use), and took approximately 40 minutes to complete. A few days before the 4‐month follow‐up was due, participants were automatically sent the questionnaire in the same format (online or postal) that they had chosen to complete at baseline. For those who did not respond promptly, a standard procedure was followed in terms of sending out reminders for all follow‐ups. This involved: sending an email reminder; phoning the participant; posting a questionnaire (a second copy was posted for those who were completing the paper version); posting just the primary outcome questions (the PHQ‐9); finally, phoning participants to ask them to post back the PHQ‐9 or offering to complete it over the phone. After this final phone reminder was completed, no further attempts were made to collect data for that follow‐up time point. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders (6 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Elkind 1986.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Psychologists with APA membership | |
| Comparisons | 1. Plain covering envelope with rubber‐stamped return address 2. University‐printed envelope 3. Postage‐stamped 4. Business reply |
|
| Outcomes | 1. Response rate at 6 weeks 2. Response rate after 12 weeks |
|
| Topic | Health: patients' violence and harassment | |
| Mode of Administration | Postal: first‐class mail | |
| Notes | Method confirmed by the author; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Enger 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | College graduates | |
| Comparisons | 1. 2‐page questionnaire; stamped return envelope 2. 1‐page questionnaire; stamped return envelope 3. 1‐page questionnaire designed as a self‐mailer | |
| Outcomes | Response period not specified | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Erdogan 2002.
| Study characteristics | ||
| Methods | Random allocation: systematic assignment | |
| Data | Advertising agency managers who had not responded to a questionnaire mailed 2 weeks previously | |
| Comparisons | 1. Original replacement follow‐up mailing: a colour department‐headed cover letter, original questionnaire plus self‐addressed, first‐class stamped return envelope 2. Photocopy replacement follow‐up mailing: a colour department‐headed cover letter, photocopied questionnaire plus self‐addressed, first‐class stamped return envelope 3. Post card: colour departmental follow‐up postcard only 4. Letter: Colour department‐headed follow‐up letter only | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Ernst 2018.
| Study characteristics | ||
| Methods | Random allocation: using a random number algorithm in Microsoft Excel | |
| Data | Primary care gynaecologists, Germany | |
| Comparisons | Email with link to survey vs. postal letter with link to survey vs. mailed questionnaire | |
| Outcomes | Response after 6 weeks (reminder email and postal reminder with paper questionnaire) | |
| Topic | Health (case‐control study on care‐related factors associated with antepartal diagnosis of intrauterine growth restrictions) | |
| Mode of Administration | Electronic (Web survey)/postal | |
| Notes | Survey comprised Internet‐based or paper questionnaire; 21 items targeting gynaecologists' practice routine regarding intrauterine growth restriction (IUGR). Estimated 5‐10 minutes for completion Participants in the mixed‐mode (email/postal) group received an invitation to the Internet‐based survey via email (with URL). Non‐responders sent a reminder email with URL after 3 weeks and postal letter with a paper‐based questionnaire after 6 weeks. The mixed‐mode group (postal/email) received a postal invitation to Web survey, with written URL. Non‐responders sent reminder letter after 3 weeks, and postal letter with questionnaire after 6 weeks. The online survey design and layout was made to be as comparable to the postal version as possible. The questions were displayed in the same order and format. A professional web designer developed the study website that hosted the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: using a random number algorithm in Microsoft Excel |
| Allocation concealment? | Yes | Random allocation: using a random number algorithm in Microsoft Excel |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Etter 1996.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | French‐speaking patients at a medical practice in the suburbs of Geneva who had recently consulted a physician and who lived in Geneva at the time of data collection | |
| Comparisons | 1. University letterhead; cover letter signed by the researchers; bsiness reply envelope addressed to the University of Geneva
2. Medical practice letterhead; cover letter signed by the director of the medical practice; business reply envelope addressed to the practice Packages sent to non‐respondents every 10 days up to a maximum of 4 times Reminder postcards sent 2 days after first and second mailings |
|
| Outcomes | Response within 45 days | |
| Topic | Health: patient satisfaction | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Etter 1998a.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Students, faculty, administrative and technical staff of a university (Geneva, Switzerland) | |
| Comparisons | 1. Sent saliva vial; offered participation in lottery; pen incentive
2. Saliva vial; pen incentive
3. Saliva vial; offered participation in lottery
4. Saliva vial
5. Offered participation in lottery; pen incentive
6. Pen incentive
7. Offered participation in lottery
8. None Best response intervention was sent as follow‐up. |
|
| Outcomes | — | |
| Topic | Health: health status using SF‐36, smoking habits, self‐efficacy | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; mean age: 28.5 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Etter 1998b.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Residents of Geneva | |
| Comparisons | 1. Professional layout; prior feedback letter 2. Professional layout; no prior feedback letter 3. Standard layout; prior feedback letter 4. Standard layout; prior feedback letter | |
| Outcomes | — | |
| Topic | Health: use of health services, satisfaction with medical care | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; mean age: 32 years; equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Etter 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of various health insurance plans aged 19‐45 (Geneva, Switzerland) | |
| Comparisons | 1. Light green paper questionnaire
2. White paper questionnaire 5 follow‐up reminder questionnaires were used. |
|
| Outcomes | Response within 50 days | |
| Topic | Health: health status, health related lifestyles, use of medical services, satisfaction with medical care, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | Age: 19‐45 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Etzel 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Random sample of bank credit card holders on a list provided by a bank, USA | |
| Comparisons | 1. No follow‐up 2. Follow‐up without duplicate questionnaire and return envelope sent 5 days after initial mailing 3. Follow‐up with duplicates sent 5 days after initial mailing | |
| Outcomes | Response within 17 days | |
| Topic | Non‐health: finance ‐ credit care usage | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Evans 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Men diagnosed with prostate cancer | |
| Comparisons | 1. Unconditional 30 minutes prepaid phone card 2. Conditional 30 minutes prepaid phone card |
|
| Outcomes | Response period not specified | |
| Topic | Health: Dietary supplementation use in cancer patients | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method not specified |
| Allocation concealment? | Unclear | Random allocation: method not specified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
Falthzik 1971.
| Study characteristics | ||
| Methods | Random allocation: odd numbered firms received closed question; even numbered firms received open‐ended question | |
| Data | Personnel departments of 200 firms listed in Fortune magazine's list of the 500 largest firms in the US | |
| Comparisons | 1. Closed question 2. Open‐ended question | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: characteristics while hiring college graduates | |
| Mode of Administration | Postal | |
| Notes | Random allocation unclear | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Faria 1990.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Homeowners residing in a medium‐sized US city on the 'city property owners' listing | |
| Comparisons | 1. Telephone pre‐contact 1‐3 days before questionnaire mailing 2. Letter pre‐notification sent 2 days before questionnaire mailing 3. No pre‐contact | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Faria 1992.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Individuals listed on the company mailing list of a major manufacturer | |
| Comparisons | 1. University sponsor; no promised contribution to charity 2. University sponsor; promised contribution to a specified charity 3. University sponsor; promised contribution to 1 of 3 charities selected by respondent 4. Commercial sponsor; no promised contribution to charity 5. Commercial sponsor; promised contribution to charity 6. Commercial sponsor; promised contribution to 1 of 3 charities selected by respondent | |
| Outcomes | Response within 23 days | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Faria 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Patients with acute stroke | |
| Comparisons | 1. Questionnaire with stamped return envelope 2. Questionnaire with free post‐return envelope | |
| Outcomes | — | |
| Topic | Health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Farley 2014.
| Study characteristics | ||
| Methods | Random allocation: RAND function in Excel | |
| Data | Healthcare professionals involved in the care and management of patients with a psychosis diagnosis | |
| Comparisons | Shorter vs. longer questionnaire | |
| Outcomes | Response after 5 weeks (2 reminders) | |
| Topic | Health (identifying opinion leaders for behaviour‐change interventions in healthcare) | |
| Mode of Administration | Postal or electronic (choice for all) | |
| Notes | Longer ‐ 22 questions; shorter ‐ 20 questions Participants were given a choice of paper and online (accessed via a hyperlink in an email) versions of both questionnaires. Individualised pre‐notification letters were sent. A reminder email and link to the online questionnaire was sent two weeks later to those who had not responded. Three weeks later, a paper‐based reminder with a paper copy of the questionnaire was sent to all remaining non‐responders. The questionnaires contained different Opinion Leader identification questions, and as such these differences may have confounded the results. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: RAND function in Excel |
| Allocation concealment? | Yes | Random allocation: RAND function in Excel |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | 75 questionnaires were returned as staff had left the NHS Trust. |
| Selective reporting | Yes | Response after 5 weeks (2 reminders) reported in full |
| Other sources of bias | No | The questionnaires contained different Opinion Leader identification questions and, as such, these differences may have confounded the results. |
Farmer 2005.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | People recruited to a programme intended to characterise people with a family history of type 2 diabetes | |
| Comparisons | Limited follow‐up (single questionnaire at 1 year) vs. intensive follow‐up (different questionnaires at 1, 6 and 12 months) | |
| Outcomes | Response to a 1‐year follow‐up questionnaire | |
| Topic | Health (well‐being and anxiety questionnaires with diabetes screening) | |
| Mode of Administration | Postal | |
| Notes | Limited questionnaire follow‐up: participants received no additional questionnaires, first contact after the letter giving test results was 1‐year questionnaire. Intensive questionnaire follow‐up: following attendance for screening, further questionnaires were sent with the result letter at 1 month, 6 months, and 1 year of follow‐up. The questionnaire sent with the results letter was three pages long and asked about satisfaction with the procedures for testing encountered. A subsequent questionnaire at 6 months was two pages long in length and consisted of the WBQ‐12, the SSAI‐SF, and two questions asking whether the participants thought they might have, or be at risk of developing, diabetes. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response to a 1‐year follow‐up questionnaire reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Feigelson 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 4000 colorectal cancer (CRC) survivors | |
| Comparisons | Email link to web survey with mail follow‐up vs. email link to web survey with interactive voice response (IVR) follow‐up. | |
| Outcomes | Response after one follow‐up | |
| Topic | Health (colorectal cancer) | |
| Mode of Administration | Postal/electronic | |
| Notes | 17‐questions. All participants who completed the survey received a $10 gift card in the mail. Participants were informed of this compensation when they were first contacted and asked to participate in the study. Participants received up to 2 email letters of invitation (11 days apart) which included a link to a secure website to complete the survey. Non‐responders in the mail follow‐up arm received a mailed survey, and non‐responders in the interactive voice response (IVR) arm received the survey as an IVR call. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after one follow‐up reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Feild 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Full‐time teaching faculty members of a large southeastern university (US) | |
| Comparisons | 1. Signed by male investigator; sent to male subject 2. Signed by male investigator; sent to female subject 3. Signed by female investigator; sent to male subject 4. Signed by female investigator; sent to female subject 5. Signed by both male and female investigators; sent to male subject 6. Signed by both male and female investigators; sent to female subject | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: short form of the attitudes towards women scale | |
| Mode of Administration | Postal | |
| Notes | Equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Felix 2011.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated using the RANDBETWEEN command in Microsoft Excel | |
| Data | Authors who had published research on maternal health | |
| Comparisons | Pre‐notification email vs. no pre‐notification Pleading email invitation vs. non‐pleading email invitation | |
| Outcomes | e‐completion and e‐submission after 2 reminders over 5 weeks | |
| Topic | Health (perceptions of the generalisability of maternal health research from one setting to another in low‐income countries.) | |
| Mode of Administration | Electronic (web survey) | |
| Notes | 23 questions (5 open‐ended). During piloting, the survey took about 10 minutes to complete. The email invitation contained a hyperlink to the Web‐based survey. Participants were required to answer questions by clicking points on a Likert scale or entering free text for open‐ended questions. On completion of the survey, participants were asked to click a submit button. The questionnaire was initially piloted by work colleagues of one author. Email reminders were sent to all non‐responders at weeks 2 and 5. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated using the RANDBETWEEN() command in Microsoft Excel |
| Allocation concealment? | Yes | Random allocation: computer‐generated using the RANDBETWEEN() command in Microsoft Excel |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ferrell 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Practitioners in managerial or administrative capacities listed in the American Marketing Association roster | |
| Comparisons | 1. Questionnaire sent to home address 2. Questionnaire sent to work address | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: marketing terms used by organisations, description of jobs, and their firm | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Finn 1983.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Heads of households in the trading area of certain financial institutions. The target area was a middle to high‐income section of the city and included all age groups and family sizes. | |
| Comparisons | 1. Return envelope with standard first class stamp and typed return address 2. Pre‐printed business reply envelope | |
| Outcomes | Response within 29 days | |
| Topic | Non‐health: finance ‐ usage of financial institutions, attitudes about local banks, savings and loan associations | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Finsen 2006.
| Study characteristics | ||
| Methods | Random allocation: alphabetical order | |
| Data | Norwegian residents aged between 40 and 65 years | |
| Comparisons | 1. Unconditional; 1 scratch lottery worth 20 Norwegian Kroner (NOK) 2. Unconditional; 2 scratch lotteries each worth 20 Norwegian Kroner 3. Conditional; 2 scratch lotteries each worth 20 Norwegian Kroner on reply within one week 4. Unconditional; 50 NOK 5. Control |
|
| Outcomes | Response rate at 6 weeks | |
| Topic | Health: history of surgery | |
| Mode of Administration | Postal | |
| Notes | Age: 51.4 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Fiset 1994.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Dentists insured by a major malpractice carrier in 2 western states (US) | |
| Comparisons | Experiment 1:
1. $5 incentive
2. $10 incentive
Follow‐up with postcard after 1 week Experiment 2: 1. $5 incentive 2. $10 incentive Follow‐up with postcard after 1 week Questionnaire package sent to non‐responders again at 3 and 7 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Health: Dentist relationship of dental malpractice claims to decisions about clinical practice | |
| Mode of Administration | Postal | |
| Notes | Mean age: 37‐41.4 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Fluss 2014.
| Study characteristics | ||
| Methods | Random allocation: electronic randomisation programme | |
| Data | 4600 residents in Grampian (north of Scotland, UK) aged 25 years and over | |
| Comparisons | Single‐sided vs. double‐sided questionnaire Electronic (Web) response option vs. mail response only | |
| Outcomes | Response after 2 weeks (1 reminder) | |
| Topic | Health (pain and pain management) | |
| Mode of Administration | Postal and electronic | |
| Notes | 20‐page study questionnaire included questions on demographic characteristics (gender, age, and educational background), health (SF‐36), pain and pain management (and chronic pain grade). Either received a 10‐sheet (double‐sided) or a 20‐sheet (single‐sided) questionnaire. Selected persons were sent a notification letter that they had been selected for the study. One week later they were sent a survey pack comprising an invitation letter, an information sheet, the questionnaire and an SAE. Potential participants were advised to read the information sheet and to complete and return the questionnaire if they wished to take part. The invitation letter for those in the web option groups contained, in addition, the URL link to the electronic questionnaire and their individual ID number and password for its access. Non‐respondents were sent a second survey pack appropriate to their randomisation group, 3 weeks after the first contact (i.e. two weeks after the questionnaire distribution). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: electronic randomisation programme |
| Allocation concealment? | Yes | Random allocation: electronic randomisation programme |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | 183 questionnaires were found invalid (for example, due to an invited participant being deceased or no longer resident at the given address). |
| Selective reporting | Yes | Response after 2 weeks (1 reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ford 1967a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Chenoa | |
| Comparisons | 1. Advance letter 2. No advance letter | |
| Outcomes | Response within 30 days | |
| Topic | Non‐health: consumer shopping survey | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ford 1967b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Beardstown | |
| Comparisons | 1. Advance letter 2. No advance letter | |
| Outcomes | Response within 30 days | |
| Topic | Non‐health: consumer shopping survey | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ford 1968.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households | |
| Comparisons | 1. Questionnaire consisted of 1 sheet, printed on both sides which, when folded, had four 8.5 x 11" pages of questions.
2. Questionnaire mimeographed on 1 side only and stapled, so had four pages of 8.5 x 14". All participants were sent an advance letter 12 days before the questionnaire was sent. |
|
| Outcomes | Response within 23 days | |
| Topic | Non‐health: consumer shopping survey | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Foushee 1990.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SAS | |
| Data | Tour operators in Europe, South America, and Japan | |
| Comparisons | 1. Early follow‐up with postcard (3 weeks) 2. Late follow up with postcard (6 weeks) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: potential for attracting and accommodating foreign visitors to national park | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Fowler 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients age 18+ who had at least one primary care visit during the previous 6 months, Greater Boston, US | |
| Comparisons | Electronic vs. postal; electronic only vs. mixed‐mode reminder (push to web); postal only vs. mixed‐mode reminder (push to web) | |
| Outcomes | Response after reminders | |
| Topic | Health (medical care experiences) | |
| Mode of Administration | Electronic and mixed mode | |
| Notes | 56 questions (standard Clinician and Group CAHPS survey); the paper questionnaire was 12 pages, including a cover page and unused back page. The layout of the Internet version was as close as possible to the paper version. Email/letter, one week follow‐up for non‐respondents and further reminder after an additional week. A. Internet: link through portal: patients were sent an email telling them that they had a new message in their portal, link to survey in the message. Second email was sent to everyone a week later. B. Internet: link without using portal. Patients were sent a personalised email that was similar to the letter patients received through their portal with link to survey. Non‐respondents sent a reminder email 1 week after the initial email and a second sent 1 week later. C. Sequential web‐mail protocol, with Internet link followed by mail to non‐respondents. Mail pre‐notification of email survey, then as protocol B. With final paper questionnaire by mail with cover letter and SAE. D. Mail only questionnaire with cover letter, and SAE, reminder postcards after 2 weeks. A further 2 weeks, non‐respondents sent 2nd questionnaire |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Frederiks 2020.
| Study characteristics | ||
| Methods | Random allocation: random integer generator | |
| Data | Randomly‐selected households in the state of Victoria, Australia | |
| Comparisons | Message printed in blue on the front of the envelope vs. no message Unconditional non‐monetary incentive (magnet with science agency logo) vs. conditional prize draw to win one of five $200 retail gift cards vs. no incentive Post‐it note with handwritten "thank you" vs. no post‐it Reminder postcard vs. no reminder | |
| Outcomes | Response period not specified | |
| Topic | Non‐health (household's energy consumption) | |
| Mode of Administration | Postal or electronic | |
| Notes | Single A3 page (folded in half to form a booklet) with a one‐page information sheet and 3 pages of questions. Information sheet for some versions of the survey referred to a prize draw (8 versions) or token fridge magnet (8 versions). Participants could complete the survey either by filling out and returning the paper form (using the reply‐paid envelope) or answering the questions online (using a survey URL printed on the form). The information sheet also included 'survey access code' unique to each of the 24 versions. This code was used by participants to access the online survey, as well as allowing the research team to determine which version of the survey each participant received. Envelope message "stating ‘Help create Australia's energy future’" |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random integer generator |
| Allocation concealment? | Yes | Random allocation: random integer generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Responses reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Fredrickson 2005.
| Study characteristics | ||
| Methods | Random allocation: SAS programme | |
| Data | Participants in a Kansas Medicaid managed care plan, US | |
| Comparisons | Group 1 ‐ Standard mailing vs. group 2 ‐ User‐friendly (standard mailing plus Spanish‐language option and low‐literacy correspondence) vs. Group 3 ‐ User‐friendly mailing plus conditional non‐monetary incentive ($10 voucher) | |
| Outcomes | Response after 2 reminders (3 weeks) | |
| Topic | Health (satisfaction with healthcare plans) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Mailings were sent to arrive on Friday or Saturday when respondents may have time to complete the questionnaire. A pre‐notification letter was followed 2 weeks later by the questionnaire with a cover letter and an SAE. A reminder postcard was sent 1 week later. Two weeks after the reminder postcard the questionnaire was sent again. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: SAS programme |
| Allocation concealment? | Yes | Random allocation: SAS programme |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 2 reminders (3 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Freise 2001.
| Study characteristics | ||
| Methods | Random allocation: using dice | |
| Data | Last 1400 discharged patients of the University hospital of Cologne on 14/02/2000 | |
| Comparisons | 1. 12‐page questionnaire 2. 8‐page questionnaire 3. 4‐page questionnaire |
|
| Outcomes | Response period not specified | |
| Topic | Health: Cologne patient questionnaire | |
| Mode of Administration | Postal | |
| Notes | Age: above 18 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Friedman 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Travel agents who subscribed to a travel magazine | |
| Comparisons | 1. Author had 'Hispanic' name 2. Author had 'Jewish' name 3. Ethnicity of author not identifiable | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: ethnic identification | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Friedman 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in telephone directories of 2 suburban areas in the greater New York Metropolitan area | |
| Comparisons | 1. Black sponsor signature; 25 cents incentive 2. Black sponsor signature; no incentive 3. White sponsor signature; 25 cents incentive 4. White sponsor signature; no incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Non‐health: attitudes towards the Negroes Scale | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Furse 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Microwave oven owners listed in a major manufacturer's warranty registration records | |
| Comparisons | 1. No personal or charity incentive offered 2. Charity incentive (promise of $1 to charity of respondent's choice for returned questionnaire) 3. 50 cents enclosed with questionnaire 4. $1 enclosed with questionnaire 5. 50 cents enclosed with questionnaire and charity incentive (promise of $1 to charity of respondent's choice for returned questionnaire) 6. $1 enclosed with questionnaire and charity incentive (promise of $1 to charity of respondent's choice for returned questionnaire) | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Furst 1979.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Secretaries of school principals | |
| Comparisons | 1. Pre‐notification 2. No pre‐notification | |
| Outcomes | Response period not specified | |
| Topic | Health: Eysenck Personality Inventory (EPI) | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author. Informed that allocation concealment was poor | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Futrell 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Salesmen from a national hospital supply company | |
| Comparisons | 1. Instruction to return the questionnaire unsigned
2. Asked to sign the questionnaire 2 follow‐up letters sent 10 days apart 2 weeks after questionnaire sent |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: salesman's attitudes towards their job, evaluation of job performance by supervisors | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Futrell 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Grocery store managers | |
| Comparisons | 1. Allowed to remain anonymous 2. Required to sign questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: job attitudes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Futrell 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Farmers and ranchers | |
| Comparisons | 1. Questionnaire and letter 2. Questionnaire and letter; non‐respondents after 2 weeks sent letter and questionnaire 3. Questionnaire and letter; non‐respondents after 2 weeks sent letter only 4. Questionnaire and letter; non‐respondents after 2 and 4 weeks sent letter and questionnaire 5. Questionnaire and letter; non‐respondents after 2 and 4 weeks sent letter only 6. Questionnaire and letter; non‐respondents after 2, 4 and 6 weeks sent letter and questionnaire 7. Questionnaire and letter; non‐respondents after 2, 4 and 6 weeks sent letter only | |
| Outcomes | — | |
| Topic | Non‐health: finance ‐ perceptions of agricultural producers regarding financial lending institutions | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Futrell 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Industrial accountants | |
| Comparisons | 1. No statement assuring anonymity; asked to return questionnaire the same day it was received 2. No statement assuring anonymity; asked to return questionnaire at their leisure 3. Statement assuring anonymity; asked to return questionnaire the same day it was received 4. Statement assuring anonymity; asked to return questionnaire at their leisure | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: role conflict, role clarity, job tension, job satisfaction | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gajic 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random sample of 3000 Ontario residents | |
| Comparisons | No incentive vs. unconditional monetary incentive ($2) vs. lower conditional non‐monetary incentive (lottery: 10 prizes of $25) vs. higher conditional non‐monetary incentive (lottery: 2 prizes of $250) | |
| Outcomes | Response after 3 weeks (1 reminder) | |
| Topic | Health (presence and magnitude of health‐related externalities) | |
| Mode of Administration | Postal invitation to web survey | |
| Notes | The survey comprised four main parts, > 60 questions; 1) willingness to contribute money to a charity that provided financial assistance so recipients could obtain desired healthcare (12 questions); 2) subjects willingness to pay for their own treatment (16 questions); 3) instrument developed by social psychologists to measure an individual's social values orientation (24 questions); 4) socioeconomic and demographic questions The letter of invitation explained the research topic, invited respondents to participate in the study (with a response deadline) and provided both an individual ID code and a simple McMaster University web address to which to respond. Potential respondents were invited to complete the survey online. A second, follow‐up letter of invitation was mailed 3 weeks after the initial letter. Returned non‐deliverable letters were logged in a central database following the initial mailing. All invitation letters were identical except for minor wording differences associated with each incentive. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 3 weeks (1 reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gajraj 1990.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Customers of a major public utility, comprising households in southwestern Ontario | |
| Comparisons | 1. No incentive
2. $0.50 included
3. Promise of $0.50 on return of completed questionnaire
4. Pen included
5. Promise of pen on return of completed questionnaire
6. Inclusion in share of winning from 5 Super Lotto lottery tickets
7. Promise of inclusion in share of 5 Super Lotto lottery tickets on return of completed questionnaire All sent same questionnaire, mailing envelope, computer‐printed label and return envelope. Cover letters varied only in stating the amount of incentives. |
|
| Outcomes | Response within 25 days | |
| Topic | Non‐health: general area of energy conservation | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author. Informed that allocation concealment was adequate | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Galesic 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 3472 participants accessed survey through banners on 2 major job‐search websites | |
| Comparisons | Respondents were told: "the survey lasts 10 minutes" vs. "20 minutes" vs. "30 minutes". | |
| Outcomes | Started questionnaire; completed questionnaire | |
| Topic | Health (quality of life, subjective health, attitudes, and behaviours of unemployed people in Croatia) | |
| Mode of Administration | Web survey | |
| Notes | The questionnaire, programmed in WARP‐IT software (RM Plus 2003), consisted of 10 screening questions on demographics, followed by about 180 questions divided into 20 blocks. Each question block occupied approximately one screen and contained questions on a related topic, e.g. on everyday activities or the respondents' financial situation. The study was conducted within a web survey on quality of life, subjective health, attitudes, and behaviours of unemployed people in Croatia. The survey was advertised via banners briefly describing the survey topic on two major job‐search sites. The respondents were volunteers who visited the sites and clicked on the banner. Respondents were randomly assigned to three different conditions regarding the announced length. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Numbers of participants who started and completed questionnaire reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Garcia 2014.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Rheumatoid arthritis patients, Southern California, US | |
| Comparisons | Mail with follow‐up letter vs. mail with follow‐up telephone call | |
| Outcomes | Response within one month (with one reminder after 2 weeks) | |
| Topic | Health (Health Assessment Questionnaire disability index and pain scale, EuroQol 5) | |
| Mode of Administration | Postal | |
| Notes | 7‐page survey. Patients were given the option to decline participation, and those who received mail surveys were also sent an "opt‐out" postcard should they choose not to participate. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | Participants and personnel were not blinded. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gaski 2004a.
| Study characteristics | ||
| Methods | Random allocation: using coin toss | |
| Data | US "mass‐market" dealers of the Gillette company's paper mate division | |
| Comparisons | 1. Dissertation referencing in the cover letter 2. No dissertation referencing in the cover letter |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: behavioural relations between manufacturer and its distributor | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Gaski 2004b.
| Study characteristics | ||
| Methods | Random allocation: using coin toss | |
| Data | Wholesalers serving stationery/ office supply and school supply stores | |
| Comparisons | 1. Dissertation referencing in the cover letter 2. No dissertation referencing in the cover letter |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: behavioural relations between a manufacturer and its distributor | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Gates 2009.
| Study characteristics | ||
| Methods | Quasi‐randomisation: sequentially numbered | |
| Data | 2144 participants in the Managing Injuries of the Neck Trial (MINT), presenting to ED with whiplash injuries | |
| Comparisons | Non‐monetary incentive (£5 gift voucher) with follow‐up vs. no incentive | |
| Outcomes | Response after 1 reminder and 3 telephone calls | |
| Topic | Health (neck injury management) | |
| Mode of Administration | Postal | |
| Notes | 49 questions; 15 A4 pages; consisted of the Neck Disability Index (NDI), two standard quality of life measures (SF‐12 and EQ‐5D), and questions on resource use and beliefs about neck pain. Questionnaire was sent out with a personalised covering letter and an SAE. A second copy of the questionnaire was sent after 2 weeks, followed by up to 3 attempts to make contact by telephone to request return of the questionnaire. Finally, participants were offered the option to provide the most important outcome data by telephone. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Quasi‐randomisation: sequentially numbered |
| Allocation concealment? | Yes | Quasi‐randomisation: sequentially numbered |
| Blinding of participants and personnel | No | Neither participants nor personnel were blinded. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 1 reminder and 3 telephone calls reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gattellari 2001.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | All active fellows of the Royal Australasian College of Surgeons (RACS) | |
| Comparisons | 1. Promise of a $A10 donation to RACS for every returned questionnaire 2. No offer of donation | |
| Outcomes | Response period not specified | |
| Topic | Health: need for evidence‐based clinical practice guidelines for the management of colorectal cancer | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Gattellari 2004.
| Study characteristics | ||
| Methods | Random allocation: using block randomisation | |
| Data | Men from general practice surgeries in Sydney, Australia | |
| Comparisons | 1. Mention of deadline to return the questionnaire within 1 week 2. No mention of deadline |
|
| Outcomes | Response period not specified | |
| Topic | Health: prostate cancer screening | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Gattellari 2012.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | 1000 randomly selected Australian family physicians | |
| Comparisons | Fax pre‐contact vs. mail pre‐contact Label affixed to the seal of the envelope with printed request (Attention: to be opened by doctor only) vs. blank label Non‐responders re‐randomised: final reminder more personalised vs. less | |
| Outcomes | Response after 3 reminders (day 209) | |
| Topic | Health (management of nonvalvular atrial fibrillation) | |
| Mode of Administration | Postal | |
| Notes | Each questionnaire was printed in blue ink on a sand‐coloured 24‐page, saddle‐stitched, A4 sized booklet. All questionnaires were mailed in a yellow‐coloured envelope, with institutional title, logo, and return address printed on the top left‐hand corner. A business reply‐paid envelope was included. Faxed prompts were sent 8‐15 days before the mailout of questionnaires, and mailed advance prompts were sent 7 days before questionnaires were mailed. The first author prepared all mailouts, including the advance mailed prompt letters, whereas administrative assistants were responsible for faxing prompt letters. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gendall 1996.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | New Zealanders aged 18 and above, selected from the New Zealand electoral rolls | |
| Comparisons | 1. Cover with simple graphic design in black letters 2. Cover with complex design in black and red letters 3. Cover with different complex design in black and red letters 4. Inclusion of a picture or a photo 5. Without a picture or a photo |
|
| Outcomes | Response rate at 12 weeks | |
| Topic | Health: demography ‐ family and changing gender roles | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Gendall 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals on the electoral roll (New Zealand) | |
| Comparisons | 1. Control
2. High quality foil‐wrapped tea bag included
3. $1 coin included 2 follow‐ups sent |
|
| Outcomes | — | |
| Topic | Non‐health: role of government, attitudes to work orientations | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gendall 2005a.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | New Zealanders aged 18 and above, selected from the New Zealand electoral rolls | |
| Comparisons | 1. Personalised cover letter 2. Non‐personalised cover letter |
|
| Outcomes | Response period not specified | |
| Topic | Health: environmental issues, demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gendall 2005b.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | New Zealanders aged 18 and above, selected from the New Zealand electoral rolls | |
| Comparisons | 1. Cover design ‐ circle 2. Cover design ‐ blocks 3. Cover design ‐ no graphics |
|
| Outcomes | Response period not specified | |
| Topic | Health: demographics, disability issues, families and friends, experiences of funerals | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gendall 2005c.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | New Zealanders aged 18 and above, selected from the New Zealand electoral rolls | |
| Comparisons | 1. Two 45‐cent postage stamp 2. Foil‐wrapped Dilmah tea bag 3. Small foil‐wrapped gold coin with a 20 cent denomination 4. Large foil‐wrapped gold coin with either a 50 cent or $2 denomination 5. No incentives |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: citizenship in new land | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gendall 2008.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | New Zealand general public | |
| Comparisons | No incentive vs. two 45‐cent postage stamps vs. foil‐wrapped tea bag vs. foil‐wrapped gold chocolate coin vs. chocolate square | |
| Outcomes | Response after 2 reminders | |
| Topic | Non‐health (immigration, the role of government, advertising regulation, and work) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires for each survey not described The surveys involved an initial posting followed by two reminder letters to non‐respondents, the second with a questionnaire, the first without |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gibson 1999a.
| Study characteristics | ||
| Methods | Random allocation: randomisation sequence generated using random number function in SAS | |
| Data | Medicaid subjects from families that included at least 1 member who had been enrolled continuously in the respective programme from July‐Dec 1993 | |
| Comparisons | 1. Medicaid; no incentive
2. Medicaid; $1 incentive
3. Medicaid; $2 incentive
4. Basic Health Plan; no incentive
5. Basic Health Plan; $1
6. Basic Health Plan; $2 Non‐respondents after second mailing were randomised to receive third mailing by certified mail or by 2‐day priority mail. |
|
| Outcomes | — | |
| Topic | Health: access and use of health services, demographics | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. No information on allocation concealment provided | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gibson 1999b.
| Study characteristics | ||
| Methods | Random allocation: randomisation sequence generated using random number function in SAS | |
| Data | BHP subjects from all families that included at least 1 member who had been enrolled continuously in the respective programme from July‐Dec 1993 | |
| Comparisons | 1. Medicaid; no incentive
2. Medicaid; $1 incentive
3. Medicaid; $2 incentive
4. Basic Health Plan; no incentive
5. Basic Health Plan; $1
6. Basic Health Plan; $2 Non‐respondents after second mailing were randomised to receive third mailing by certified mail or by 2‐day priority mail. |
|
| Outcomes | — | |
| Topic | Health: access to health services, use of services, satisfaction with services, demographics | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. No information on allocation concealment provided. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gibson 1999c.
| Study characteristics | ||
| Methods | Random allocation: randomisation sequence generated using random number function in SAS | |
| Data | Non‐responding Medicaid subjects from families that included at least 1 member who had been enrolled continuously in the respective programme from July‐Dec 1993 | |
| Comparisons | 1. Certified mail 2. 2‐day priority mail | |
| Outcomes | — | |
| Topic | Health: access and use of health services, demographics | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. No information on allocation concealment provided | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Giles 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Faculty members | |
| Comparisons | 1. Combination format (CombF); satisfaction items first (S1st); 2 demographic items (DI)
2. CombF; S1st; 4DI
3. CombF; S1st; 6DI
4. CombF; S1st; 8DI
5. CombF; S1st; 10DI
6. CombF; Demographic items first (D1st); 2DI
7. CombF; D1st; 4DI
8. CombF; D1st; 6DI
9. CombF; D1st; 8DI
10. CombF; D1st; 10DI
11. Categorical Format (CategF); S1st; 2DI
12. CategF; S1st; 4DI
13. CategF; S1st; 6DI
14. CategF; S1st; 8DI
15. CategF; S1st; 10DI
16. CategF; D1st; 2DI
17. CategF; D1st; 4DI
18. CategF; D1st; 6DI
19. CategF; D1st; 8DI
20. CategF; D1st; 10DI No follow‐ups used |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: job satisfaction | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gillpatrick 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Engineers identified from the subscriber list of a major trade journal | |
| Comparisons | 1. $1 incentive 2. No incentive 3. Pre‐contact 4. No pre‐contact | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: market perceptions about CAD workstations | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gitelson 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Spectators at the Pennsylvania Farm Show who had not responded to 3 previous mailings of the questionnaire | |
| Comparisons | 1. Non‐personalised questionnaire; regular post 2. Personalised questionnaire; regular post 3. Personalised questionnaire; certified post | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: economic impact of the farm show | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gjostein 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in a colonoscopy screening study for colorectal cancer | |
| Comparisons | No incentive vs. unconditional non‐monetary incentive (lottery scratch card) Unconditional non‐monetary incentive (lottery scratch card) vs. conditional non‐monetary incentive (prize draw for an iPad) |
|
| Outcomes | Response after one reminder | |
| Topic | Health (questionnaire on risk factors for colon cancer) | |
| Mode of Administration | Mixed‐mode | |
| Notes | One‐page questionnaire: the questionnaire contained four domains: height and weight, self‐reported diagnoses, smoking and family history of colorectal cancer. Information letter (which also detailed the terms of consent for participation), questionnaire and an SAE. The questionnaire could be completed online. After 3 weeks, non‐respondents were contacted by telephone. Response rate could be influenced by two factors. Firstly, by the study group (those invited for screening and the control group). The incentive arm represented the other factor that could influence the response rate. six different groups ‐ three study arms with different incentives for those invited for screening and the control group respectively |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Unclear | Unclear if response rates adjusted for exclusions (54 postal returns) |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Glidewell 2012a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Study a: random sample of dental practitioners in Scotland | |
| Comparisons | Study a: Longer questionnaire vs. longer questionnaire plus unconditional non‐monetary incentive (£20 book voucher) vs. shorter questionnaire | |
| Outcomes | First response | |
| Topic | Health (psychological frameworks which would be predictive of evidence‐based clinical behaviour) | |
| Mode of Administration | Postal | |
| Notes | 10‐page full length (81 questions) questionnaire Participants were mailed an invitation pack (letter of invitation, questionnaire, a form requesting consent to allow the research team to access the respondent's radiograph or prescribing data from centrally held databases, a study newsletter, and a reply‐paid envelope). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Secretaries recording receipt of RCTA and RCTB survey packs were blinded to group assignment. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Glidewell 2012b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Study b: Random sample of general practitioners in the UK who were non‐responders to a previous postal questionnaire (n = 847) | |
| Comparisons | Study b: questionnaire reminder vs. postcard reminder | |
| Outcomes | First response | |
| Topic | Health (psychological frameworks which would be predictive of evidence‐based clinical behaviour) | |
| Mode of Administration | Postal | |
| Notes | 10‐page full length (81 questions) questionnaire Participants were mailed an invitation pack (letter of invitation, questionnaire, a form requesting consent to allow the research team to access the respondent's radiograph or prescribing data from centrally‐held databases, a study newsletter, and a reply‐paid envelope). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Secretaries recording receipt of RCTA and RCTB survey packs were blinded to group assignment. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Glisan 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Farmers from 6 geographical regions | |
| Comparisons | 1. Incentive ‐ monetary 2. Incentive ‐ results promised 3. Incentive ‐ control 4. Colour ‐ tan 5. Colour ‐ blue 6. Colour ‐ white 7. Stamp ‐ commemorative 8. Stamp ‐ regular | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: farm operations and costs | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Godwin 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals in 60 countries | |
| Comparisons | 1. No incentive
2. $25
3. $50 Participants were requested to return the questionnaire within 3 weeks. After 2 weeks, a single follow‐up letter with a copy of the questionnaire was sent to all respondents. |
|
| Outcomes | Response period not specified | |
| Topic | Health: family planning programmes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Goldstein 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Subscribers to a travel magazine | |
| Comparisons | 1. Postcard format first wave; postcard format second wave 2. Form first wave; form second wave 3. Postcard format first wave; form second wave 4. Form first wave; postcard format second wave | |
| Outcomes | Response period not specified | |
| Topic | Non‐health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Goodstadt 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Readers of Addictions Magazine | |
| Comparisons | 1. 25 cent incentive 2. Free book incentive 3. Promise of free book 4. No incentive | |
| Outcomes | — | |
| Topic | Non‐health: reading habits, magazine function served, the range and depth of subjects covered, overall design | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Goodwin 2020.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Parents of a child born in Cumbria, UK 2014‐15, who had not responded to 2 waves of a survey | |
| Comparisons | Postcard reminder vs. telephone reminder vs. questionnaire reminder | |
| Outcomes | Final response | |
| Topic | Health (children's oral and general health) | |
| Mode of Administration | Postal | |
| Notes | ||
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Goulao 2020a.
| Study characteristics | ||
| Methods | Random allocation: automated, central randomisation service | |
| Data | Regular attenders to the dentists and with overall good oral health | |
| Comparisons | Study a: Sticker added to the top left corner of envelope vs. no sticker | |
| Outcomes | Response after 6 weeks | |
| Topic | Health (patient‐reported outcomes in oral health and dentistry) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires were issued with a cover letter using a semi‐automated process; if not returned within 3 weeks of issue of the first questionnaire, a reminder letter and second questionnaire were sent. As well as testing whether the BCTs incorporated in a different format to the cover letter (i.e. a newsletter) encouraged return of questionnaires, we were able to test a second research question: does the timing of delivery of a newsletter affect response rates? The intervention group received the newsletter before the first questionnaires and the control group received it with the second (reminder) or after return of the first questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: automated, central randomisation service |
| Allocation concealment? | Yes | Random allocation: automated, central randomisation service |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Goulao 2020b.
| Study characteristics | ||
| Methods | Random allocation: automated, central randomisation service | |
| Data | Regular attenders to the dentists and with overall good oral health | |
| Comparisons | Study b: Standard cover letter vs. letter with behaviour change techniques in the text | |
| Outcomes | Response after 6 weeks | |
| Topic | Health (patient‐reported outcomes in oral health and dentistry) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires were issued with a cover letter using a semi‐automated process; if not returned within 3 weeks of issue of the first questionnaire, a reminder letter and second questionnaire were sent. As well as testing whether the BCTs incorporated in a different format to the cover letter (i.e. a newsletter) encouraged return of questionnaires, we were able to test a second research question: does the timing of delivery of a newsletter affect response rates? The intervention group received the newsletter before the first questionnaires and the control group received it with the second (reminder) or after return of the first questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: automated, central randomisation service |
| Allocation concealment? | Yes | Random allocation: automated, central randomisation service |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Goulao 2020c.
| Study characteristics | ||
| Methods | Random allocation: automated, central randomisation service | |
| Data | Regular attenders to the dentists and with overall good oral health | |
| Comparisons | Study c: Pre‐contact study newsletter with behaviour change techniques in the text vs. newsletter with reminder | |
| Outcomes | Response after 6 weeks | |
| Topic | Health (patient‐reported outcomes in oral health and dentistry) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires were issued with a cover letter using a semi‐automated process; if not returned within 3 weeks of issue of the first questionnaire, a reminder letter and second questionnaire were sent. As well as testing whether the BCTs incorporated in a different format to the cover letter (i.e. a newsletter) encouraged return of questionnaires, we were able to test a second research question: does the timing of delivery of a newsletter affect response rates? The intervention group received the newsletter before the first questionnaires and the control group received it with the second (reminder) or after return of the first questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: automated, central randomisation service |
| Allocation concealment? | Yes | Random allocation: automated, central randomisation service |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Green 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Teachers chosen from the Wyoming State Department of Education list of educators | |
| Comparisons | 1. Personalised cover letter 2. Non‐personalised cover letter |
|
| Outcomes | — | |
| Topic | Non‐health: courses taken in tests and measurement, attitudes towards standardised and classroom testing, interest in topics for inservice training | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Green 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Inservice teachers from the states of Wyoming and Nebraska | |
| Comparisons | 1. Offer of a summary of results vs none 2. Personalisation vs no personalisation | |
| Outcomes | — | |
| Topic | Non‐health: application of research methods and findings to classroom teaching | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Green 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Randomly selected US social workers | |
| Comparisons | 1. Demographic items placed at the beginning of the questionnaire 2. Demographic items placed at the end of the questionnaire | |
| Outcomes | — | |
| Topic | Health: attitudes and beliefs about roles of family interaction and biological factors in mental illness | |
| Mode of Administration | Postal | |
| Notes | Mean age: 44.5 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Greer 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Senior sales executives (US) | |
| Comparisons | 1. University sponsor; white questionnaire
2. University sponsor; yellow questionnaire
3. University sponsor; pink questionnaire
4. University sponsor; green questionnaire
5. Commercial research sponsor; white questionnaire
6. Commercial research sponsor; yellow questionnaire
7. Commercial research sponsor; pink questionnaire
8. Commercial research sponsor; green questionnaire
9. Academic honour society sponsor; white questionnaire
10. Academic honour society sponsor; yellow questionnaire
11. Academic honour society sponsor; pink questionnaire
12. Academic honour society sponsor; green questionnaire
13. No sponsor (PO Box); white questionnaire
14. No sponsor (PO Box); yellow questionnaire
15. No sponsor (PO Box); pink questionnaire
16. No sponsor (PO Box); green questionnaire Follow‐up sent after 3 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: company's programme for sales people | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Griffin 2011.
| Study characteristics | ||
| Methods | Random allocation: random numbers | |
| Data | Non‐respondents to a face‐to‐face survey of US veterans | |
| Comparisons | Smaller unconditional monetary incentive ($2) vs. larger unconditional monetary incentive ($5) | |
| Outcomes | First response and final response after two reminders (4 weeks) | |
| Topic | Non‐health (survey designed to characterise non‐respondents) | |
| Mode of Administration | Postal | |
| Notes | 10‐item questionnaire (one page) Surveys were mailed using first‐class postage, including a cover letter, an SAE. A reminder postcard was mailed approximately one week after the first packet. A second questionnaire packet without an incentive was mailed to any subject who did not return a blank or completed survey within 3‐4 weeks of the first mailing. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random numbers |
| Allocation concealment? | Yes | Random allocation: random numbers |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response and final response after two reminders (4 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Griffith 1999.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General medical internists in 5 Canadian provinces | |
| Comparisons | 1. Open‐ended questionnaire format 2. Close‐ended questionnaire format | |
| Outcomes | — | |
| Topic | Health: career satisfaction | |
| Mode of Administration | Postal | |
| Notes | Mean age: 51.9 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Groeneman 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People listed in the telephone directories of Toronto, Montreal, Vancouver and Winnipeg, Canada selected using 'distinctive Jewish name sampling' | |
| Comparisons | 1. $1 bill enclosed 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: travel experience and attitudes towards future trips | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Groves 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Therapeutic recreation co‐ordinators in the US | |
| Comparisons | 1. Stamped addressed return envelope included 2. Self‐adhering return address level (no envelope or postage) included | |
| Outcomes | Response period not specified | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gueguen 2003a.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | University students | |
| Comparisons | 1. Attractive photo in the email 2. Medium attractive photo in the email 3. No photo in the email 4. Male signature 5. Female signature |
|
| Outcomes | Response period not specified | |
| Topic | Health: dietary habits | |
| Mode of Administration | Electronic: email | |
| Notes | Equal males and females; language of publication is French. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Gueguen 2003b.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | Sample of individuals with email addresses ending in ".fr" picked up randomly from the Internet using specialised software | |
| Comparisons | 1. Attractive photo in the email 2. Medium attractive photo in the email 3. Less attractive photo in the email 4. No photo in the email 5. Male signature 6. Female signature |
|
| Outcomes | Response period not specified | |
| Topic | Health: dietary habits | |
| Mode of Administration | Electronic: email | |
| Notes | Language of publication is French. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Gullahorn 1959.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Former Fulbright & Smith‐Mundt grantees who had not responded to the earlier mailing of the questionnaire | |
| Comparisons | 1. Follow‐up mailings by special delivery 2. Follow‐up mailings by standard mail | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: bibliography of works emanating form Fulbright and Smith‐Mundt awards | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Gullahorn 1963.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Former Fulbright and Smith‐Mundt grantees | |
| Comparisons | 1. Questionnaire printed on green paper, sent by first‐class mail, with business‐reply return envelope 2. Green paper; first‐class, stamped return envelope 3. Green paper, third‐class mail, business‐reply return envelope 4. Green paper, third‐class mail, return envelope stamped 5. White paper, first‐class mail, business‐reply return envelope 6. White paper, first‐class, return envelope stamped 7. White paper, third‐class mail, business‐reply return envelope 8. White paper, third‐class mail, return envelope stamped | |
| Outcomes | — | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Guo 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Randomly selected community‐dwelling adults in British Columbia | |
| Comparisons | Shorter vs. longer (LC incentive vs. LC short) No incentive vs. non‐monetary incentive (instant lottery) vs. monetary incentive group ($2 prepaid coin) vs. non‐monetary incentive plus monetary incentive (both instant lottery plus $2 prepaid coin) | |
| Outcomes | Response after 3 reminders | |
| Topic | Health (general health, quality of life, and use of health services, with an emphasis on osteoarthritis) | |
| Mode of Administration | Online | |
| Notes | Short (10 minutes); longer (30 minutes). Invitation letters sent (with experimental incentive conditions) followed by 3 reminders The instant lottery was for 10 prizes of $100 (with odds of 1 in 800), and a grand prize of $1000 (with odds of 1 in 8000). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Gupta 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Medical practitioners | |
| Comparisons | 1. Telephone prompt by medical researcher 2. Telephone prompt by an experienced non‐medical research assistant | |
| Outcomes | — | |
| Topic | Health: views about clinical practice guidelines | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Göritz 2004a.
| Study characteristics | ||
| Methods | Random allocation: using computerised random number generation | |
| Data | Panellists from the German commercial online access panel | |
| Comparisons | 1. 7 X 100 (700) German Mark (DM) money lottery 2. 14 X 50 (700) DM money lottery 3. 5 X 100 (500) DM money lottery 4. 10 X 50 (500) DM money lottery 5. 3 X 100 (300) DM money lottery 6. 6 X 50 (300) DM money lottery 7. 1 X 100 (100) DM money lottery 8. 2 X 50 (100) DM money lottery 9. 8 Bonus point (BP) (1 BP is worth 50 DM) 10. 6 BP 11. 4 BP 12. 3 BP 13. Gift lottery (3 watches/5 CD‐jackets/5 alarm clocks/25 key‐ring torches). |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: personal Internet usage | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Göritz 2004b.
| Study characteristics | ||
| Methods | Random allocation: using computerised random number generation | |
| Data | Panellists from the German commercial online access panel | |
| Comparisons | 1. 2 X 90 (180) German Mark (DM) 2. 6 X 30 DM money lottery 3. 1 X 90 DM money lottery 4. 3 X 30 DM money lottery |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: evaluation of media contents | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Hackler 1973.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Mothers of ninth or tenth grade students living in 1 neighbourhood of Edmonton | |
| Comparisons | 1. No incentive
2. $1 bill incentive After 11 days, the no incentive group received $1 and the incentive group received a follow‐up phone call. |
|
| Outcomes | — | |
| Topic | Non‐health: community cohesiveness | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Hall 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 800 haematological cancer survivors (18‐80) diagnosed within last 3 years, from one Australian state cancer registry | |
| Comparisons | Enhanced invitation letter (more readable; shorter sentences, 8th grade reading level, sans serif typeface) vs. standard letter | |
| Outcomes | Response after one reminder (4 weeks) | |
| Topic | Health (survey of unmet needs and psychological disturbance of rural and urban haematological cancer survivors) | |
| Mode of Administration | Postal | |
| Notes | Included a number of standardised measures: the Survivor Unmet Needs Survey (SUNS), the Depression Anxiety and Stress Scale (DASS), the Distress Thermometer, and an adapted version of the Control Preferences Scale. Additional author‐derived questions assessing patient disease, treatment, sociodemographic, service utilisation, and Internet use Patients were contacted directly by the cancer registry without consent, as permitted by legislation and Human Research Ethics Committee approval. Initial contact involved the mailed invitation letter along with a study package that contained: an information statement, survivor questionnaire, non‐participation form, a brochure explaining the cancer registry, reply‐paid envelope, and a questionnaire package for their principal support person. The patient's physician was not involved in patient contact or recruitment. Survivors were assured that their decision to take part in this study was entirely their choice and their decision would not affect their access to care. Non‐responders were mailed a reminder letter and an additional study package approximately 4 weeks later. Return of the survey was taken as a voluntary consent to participate. Half were randomly allocated to receive the standard invitation letter (control group). The remaining half received a modified invitation letter, incorporating content and design characteristics recommended to improve written communication (intervention group). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported; 68 (31 from the enhanced letter group and 37 from the standard letter group) were later deemed ineligible as they were either unable to be contacted (n = 556), had died (n = 58) or were misdiagnosed (n = 54). |
| Selective reporting | Yes | Response after one reminder (4 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hall 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Facebook users who indicated that they were male, over 18 years of age, and interested in men | |
| Comparisons | No incentive vs. a conditional non‐monetary incentive ($20 Amazon voucher); altruistic incentive vs. none; dashboard incentive vs. none | |
| Outcomes | Survey completion during a 9‐day period of advertising on Facebook (advancing to completion screen, without skipping more than two consecutive questions) | |
| Topic | Health (HIV prevention and risk behaviours) | |
| Mode of Administration | Electronic | |
| Notes | Monetary incentive group were offered a $20 gift code to Amazon.com at the completion of the survey. Altruistic messaging group saw 8 banner messages throughout the survey, included facts related to HIV transmission (e.g. "Every 10.5 minutes, someone is infected with HIV in the United States") and statements to highlight the importance of the individual's participation (e.g. "By taking this survey, you are making your voice heard to help stop the HIV epidemic"). Dashboard group were shown a selection of participant responses from the survey and were offered a dashboard of their own data compared to responses by other men upon survey completion. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Ineligible people reported |
| Selective reporting | Yes | Response during a 9‐day period of advertising on Facebook reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Halpern 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General internists and family practitioners randomly selected from the American Medical Association's master file of physicians | |
| Comparisons | 1. $10, peppermint candy and large outgoing envelope 2. $10, no peppermint candy, large outgoing envelope 3. $10, peppermint candy, small outgoing envelope 4. $10, no peppermint candy, small outgoing envelope 5. $5, peppermint candy and large outgoing envelope 6. $5, no peppermint candy, large outgoing envelope 7. $5, peppermint candy, small outgoing envelope 8. $5, no peppermint candy, small outgoing envelope | |
| Outcomes | Response within 11 weeks | |
| Topic | Health: views about comparative merits of placebo‐controlled versus active‐controlled trials of antihypertensive drugs | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Halpern 2011a.
| Study characteristics | ||
| Methods | Random allocation: random number generator | |
| Data | 2477 critical care physicians | |
| Comparisons | Conditional non‐monetary incentive (lottery 0.001 chance of $5k) vs. conditional non‐monetary incentive (lottery 0.02 chance of $250) vs. no incentive | |
| Outcomes | Sent email reminders to non‐respondents at 5 and 10 days following initial invitation | |
| Topic | Health (organ donation after circulatory determination of death) | |
| Mode of Administration | Online survey | |
| Notes | Questionnaire completion required 5 minutes or fewer. Sent email reminders to non‐respondents at 5 and 10 days following the initial invitation. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator |
| Allocation concealment? | Yes | Random allocation: random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Halpern 2011b.
| Study characteristics | ||
| Methods | Random allocation: random number generator | |
| Data | 1000 critical care nurses | |
| Comparisons | Conditional non‐monetary incentive (lottery 0.0025 chance of $2k) vs. unconditional monetary incentive ($5) | |
| Outcomes | Single reminder sent Completed responses (> 80 items completed) | |
| Topic | Health (organ donation after circulatory determination of death) | |
| Mode of Administration | Postal survey | |
| Notes | Questionnaire completion required 5 minutes or fewer. Sent a single reminder | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator |
| Allocation concealment? | Yes | Random allocation: random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Halpern 2011c.
| Study characteristics | ||
| Methods | Random allocation: random number generator | |
| Data | 758 resident physicians | |
| Comparisons | Conditional non‐monetary incentive (lottery 0.004 chance of $2,500) vs. conditional monetary incentive ($10) | |
| Outcomes | Sent email reminders to non‐respondents at 5 and 10 days following initial invitation Completed responses (> 80 items completed) | |
| Topic | Health (physicians practice when obtaining informed consent for blood transfusion) | |
| Mode of Administration | Online survey | |
| Notes | Questionnaire completion required 5 minutes or fewer. Sent email reminders to non‐respondents at 5 and 10 days following the initial invitation |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator |
| Allocation concealment? | Yes | Random allocation: random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | No | It is possible that some of the reported results were influenced by participants communicating with each other regarding their assigned incentives. Although such contamination is unlikely to have affected the national samples used in Trials 1 and 2, the residents sampled at three hospitals in Trial 3 could indeed have communicated with each other. |
Hammink 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 880 patients of a general practice cooperative for out‐of‐hours care | |
| Comparisons | (1) Pre‐notification and follow‐up vs. (2) pre‐notification only vs. (3) follow‐up only | |
| Outcomes | First response (within 9 days) and final response (within 1 month) after one reminder | |
| Topic | Health (patients' experiences with quality aspects of care in GP cooperatives) | |
| Mode of Administration | Postal | |
| Notes | 7 double‐sided pages, 91 items. Pre‐notification letter (in the pre‐contact arm) or the questionnaire, accompanied by a cover letter signed by the director of the GP co‐operative, and a prepaid envelope (in the other arms) were sent 2‐5 days after contact with the GP cooperative; after 5‐7 days, the questionnaire was sent to subjects who had only received a pre‐notification. The follow‐up letter, without the inclusion of a copy of the questionnaire, was delivered to non‐responders 7‐9 days after mailing of the questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | Blinding of personnel not described. Participants were not blinded to intervention. |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Han 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in the National Household Education Surveys | |
| Comparisons | Lower unconditional monetary incentive ($2) vs. higher unconditional monetary incentive ($5) FedEx/priority mail vs. first‐class mail No incentive vs. unconditional monetary incentive ($5, $10, $15, $20) | |
| Outcomes | Response after 2 reminders | |
| Topic | Non‐health (educational activities of children and families in the US) | |
| Mode of Administration | Postal | |
| Notes | A screener survey was used to identify households with eligible children. Items collected on the screener instrument included the age, gender, school enrolment, and grade for each person of age 20 or younger living at the sampled address. A topical questionnaire was sent to the parents/guardians of the sampled child to collect data on the care and education of the sampled child. All the sampled addresses were mailed an initial screener questionnaire, an information letter, and an SAE. A thank‐you/reminder postcard was mailed to all addresses. Non‐respondents to the initial mailing were mailed a second screener packet, and the remaining non‐respondents were mailed a final screener packet. The initial mailing and first non‐response follow‐up mailing were sent through first‐class mail. The second non‐response follow‐up mailing was sent using either FedEx delivery or priority mail (randomly assigned). No monetary incentive was provided during the two follow‐up mailings. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were not reported. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | No | Likely confounding of study, and unclear randomisation ‐ 'It is worth noting that the effects of the second follow‐up mailing were due in part to Priority Mail, and a different pattern might hold if First Class Mail had been used'. |
Hancock 1940.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed on the personal tax records of the county assessors | |
| Comparisons | 1. Questionnaire and cover letter 2. As above with 25 cents incentive 3. As above with promise of 25 cents on return of questionnaire 4. Personal interview | |
| Outcomes | Response period not specified | |
| Topic | — | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hansen 1980a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in the telephone directory (Columbus, Ohio) | |
| Comparisons | 1. No pre‐contact; short form (SF) 2. No pre‐contact; long form (LF) 3. Yes/no foot in the door; SF 4. Yes/no foot in the door; LF 5. Probe foot in the door; SF 6. Probe foot in the door; LF | |
| Outcomes | Response within 35 days | |
| Topic | Non‐health: consumer's attitudes towards recent new car purchases | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hansen 1980b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Safety engineers employed by firms that require employees to wear safety hardhats | |
| Comparisons | 1. 25 cent incentive 2. Pen incentive 3. Control group | |
| Outcomes | Response within 38 days | |
| Topic | Non‐health: product evaluation and information | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hardigan 2012.
| Study characteristics | ||
| Methods | Not specified | |
| Data | 6000 dentists taken from the Florida Department of Health, Board of Dentistry | |
| Comparisons | Choice (mail or web‐based), postal mail, or web‐based | |
| Outcomes | Survey, 2‐week follow‐up with additional survey, 1 week later reminder postcard by mail | |
| Topic | Tobacco use by dental patients | |
| Mode of Administration | Postal/electronic (email and web) | |
| Notes | 28 questions; 4 pages; A4 Dentists who were randomised to Group A received a mailing which contained a cover letter describing the study. The envelope also contained the Florida Tobacco Control Survey 2009; a pre‐paid, self‐addressed return envelope; and a refusal postcard. Dentists were given the choice to complete the survey via mail or online. They were provided the website address, as well as a unique survey number to type in on the home page of the online survey. After entering their survey number on the homepage, the respondents were directed through a series of questions. A response to each question was required in order for the survey to proceed to the next question. Once the survey was completed, results were stored in a master database. If no response was obtained by 2 weeks after the first mailing, an additional survey was sent by mail, which the dentist again had the option of completing online. The website was displayed at the top of the first page, along with the dentists' unique survey number. If no response was obtained 1 week later, a reminder postcard was sent via mail. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation ‐ method unspecified |
| Allocation concealment? | Unclear | Random allocation ‐ method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Stated outcomes reported |
| Other sources of bias | Yes | Potential sources of bias considered |
Hardigan 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random sample of 7200 US practicing pharmacists | |
| Comparisons | Shorter vs. longer questionnaire; demographic items first vs. last; postal vs electronic; email invitation to web survey vs. postal ('hybrid') invitation to web survey | |
| Outcomes | Final response (after 2 reminders) | |
| Topic | Non‐health (job satisfaction) | |
| Mode of Administration | Postal and electronic | |
| Notes | Longer questionnaire was 60 questions and 4 pages; shorter questionnaire was 36 questions and 2 pages. Pharmacists in the postal group were sent an envelope containing a letter describing the study, a questionnaire, an SAE, and a refusal postcard. If a response was not received within 2 weeks after the first mailing, another questionnaire was sent by mail. If no response was received 2 weeks after the second mailing, a reminder postcard was mailed. Pharmacists in the email group were sent an email inviting them to partake in the online survey. The message provided a URL directing them to the survey, as well as a refusal link if they preferred not to participate, or be contacted again. If the link to the survey was chosen, the participant was directed to the questionnaire. A response to each question was not required in order for the survey to proceed to the next question. Once the survey was completed, results were stored in a master database. If a response was not received within 2 weeks, a second email message was sent providing a survey link as well as a refusal link. If a response was not received 2 weeks later, a final email reminder was sent. Pharmacists in the hybrid group were mailed a postcard describing the study. This postcard provided a URL directing them to the survey, as well as a refusal link if they preferred not to participate or be contacted again. Once the survey was completed, results were stored in a master database. If a response was not received within 2 weeks after the first mailing, another postcard directing participants to the online survey was sent by mail. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hardy 2016.
| Study characteristics | ||
| Methods | Random allocation: computer random number generation | |
| Data | First‐time mothers who chose to have an epidural, UK | |
| Comparisons | Conditional non‐monetary incentive (£10 gift voucher) with first mailing vs. with reminder mailings | |
| Outcomes | Response after one mailing (incentive with first contact group); response after 2 reminders (incentive with reminder group) | |
| Topic | Health (women's health, well‐being and health service use one year following the birth of their baby) | |
| Mode of Administration | Postal/electronic | |
| Notes | 12‐page questionnaire. Cover letter included a sentence explaining that the voucher was to thank participants for their time and effort. For the incentive reminder letter group, the cover letter sent at first mailout did not mention the incentive. If the questionnaire was not returned, all reminder letters detailed the promise of a £10 gift voucher on return of a completed questionnaire. For both groups, women were additionally contacted electronically and via text message if the contact details were available. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer random number generation |
| Allocation concealment? | Yes | Random allocation: computer random number generation |
| Blinding of participants and personnel | No | BUMPES trial staff were aware of the allocation due to the nature of the interventions, and the practicalities involved in sending the letters and the vouchers. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | 8 exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Harris 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A randomly selected sample of respondents | |
| Comparisons | 1. Business‐reply return envelope enclosed 2. Stamped‐reply envelope enclosed | |
| Outcomes | Response within 4 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Harris 2008.
| Study characteristics | ||
| Methods | Random allocation: random number tables | |
| Data | 1156 major trauma patients | |
| Comparisons | Conditional non‐monetary incentive (AUS $4 instant lottery ticket) vs. no incentive | |
| Outcomes | Response at 4 weeks after initial mailing and after 6 months, at the end of the study | |
| Topic | Health (outcomes after major trauma) | |
| Mode of Administration | Postal | |
| Notes | 7‐page questionnaire containing 34 questions pertaining to general health (and possible demographic and socioeconomic predictors of health); took approximately 20 minutes to complete The major prize was AU$50,000 per year, for 20 years. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number tables |
| Allocation concealment? | Yes | Random allocation: random number tables |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Harrison 2002.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Adults selected from a Health Authority Register (North West England) | |
| Comparisons | 1. Reply envelope with first‐class stamp 2. Pre‐paid business‐franked reply envelope | |
| Outcomes | — | |
| Topic | Health: health questionnaire | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly 18‐45 years; equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Harrison 2004.
| Study characteristics | ||
| Methods | Random allocation: using random number generation, method unspecified | |
| Data | Patients referred to a community‐based exercise referral scheme | |
| Comparisons | 1. Pre‐warning letter 2.No pre‐warning letter |
|
| Outcomes | Response rate at 6 weeks | |
| Topic | Health: quality of services offered at the community‐based referral scheme | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: using random number generation, method unspecified |
| Allocation concealment? | Unclear | Random allocation: using random number generation, method unspecified |
| Blinding of participants and personnel | Yes | Participants remained unaware as to group allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Harvey 1986.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | A random sample of people living in the West Midlands, UK, listed on the electoral register | |
| Comparisons | 1. Reply envelope with first‐class stamp 2. Reply envelope with second‐class stamp | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: interest in fine art | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Hatch 2017.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Patients from 26 UK ICUs | |
| Comparisons | 4 pages vs. 8 pages | |
| Outcomes | First response 3 months after ICU discharge | |
| Topic | Health (quality of life, the incidence of depression, and the incidence of post‐traumatic stress disorder following at least 24 h of treatment at an ICU) | |
| Mode of Administration | Postal | |
| Notes | 4 pages vs. 8 pages, all pages were single‐sided and numbered Initial packs sent at 3 months contained a personally‐addressed letter inviting participation, a three‐page study information leaflet and a consent form. All documents prepared using a high‐quality laser printer, with invitation letter on Oxford University‐headed paper. Trial co‐ordinator signed each letter. We printed each questionnaire on different coloured paper and bound them with a removable clip, all pages single‐sided and numbered. Used a uniform design, large font size and generous spacing. All packs contained a freepost return envelope. All packs included an ICON branded pen and tea bag as incentives; the tea bag label invited participants to enjoy a cup of tea whilst completing questionnaire. We gave all patients a letter introducing the study at ICU discharge: it explained that they might receive mail from the study team. Patients were eligible if they received level 3 care (as defined by the Intensive Care Society, London) in an ICU for at least 24 h. We excluded patients if they were under 16 years old. The group A pack contained 4 questionnaire pages (one page EuroQol 5 dimensions‐3 level (EQ‐5D‐3 L) questionnaire, two pages each containing a single visual analogue scale, and a single page demographics questionnaire); the group B pack contained 8 questionnaire pages (the group A pack, plus a two‐page Hospital Anxiety and Depression Scale (HADS) questionnaire and a two‐page Post‐traumatic stress disorder Check List‚ Civilian version (PCL‐C) questionnaire |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hathaway 2021a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Cancer centre population: participants were those diagnosed with invasive and in situ cancer, benign diseases, and patients who were screened without a cancer diagnosis, US | |
| Comparisons | Study a: concise vs. wordy text in web survey email | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (cancer centre patients experience during COVID‐19 pandemic) | |
| Mode of Administration | Electronic | |
| Notes | 143 total items across 26 webpages. Email sent with a survey link for each trial condition. Up to two reminder emails were sent in 4‐day intervals. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions/attrition not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hathaway 2021b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Cancer centre population: participants were those diagnosed with invasive and in situ cancer, benign diseases, and patients who were screened without a cancer diagnosis, US | |
| Comparisons | Study b: unconditional non‐monetary incentive vs. no incentive | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (cancer centre patients experience during COVID‐19 pandemic) | |
| Mode of Administration | Electronic | |
| Notes | 143 total items across 26 webpages. Email sent with a survey link for each trial condition. Up to two reminder emails were sent in 4‐day intervals. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions/attrition not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hathaway 2021c.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Cancer centre population: participants were those diagnosed with invasive and in situ cancer, benign diseases, and patients who were screened without a cancer diagnosis, US | |
| Comparisons | Study c: conditional non‐monetary incentive vs. no incentive | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (cancer centre patients experience during COVID‐19 pandemic) | |
| Mode of Administration | Electronic | |
| Notes | 143 total items across 26 webpages. Email sent with a survey link for each trial condition. Up to two reminder emails were sent in 4‐day intervals. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions/attrition not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hathaway 2021d.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Cancer centre population: participants were those diagnosed with invasive and in situ cancer, benign diseases, and patients who were screened without a cancer diagnosis, US | |
| Comparisons | [Study d: mailed pre‐notification letter vs. pre‐notification postcard | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (cancer centre patients experience during COVID‐19 pandemic) | |
| Mode of Administration | Electronic | |
| Notes | 143 total items across 26 webpages. Email sent with a survey link for each trial condition. Up to two reminder emails were sent in 4‐day intervals. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions/attrition not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hauw‐Berlemont 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | ICU providers (physicians and advanced practice providers) at a tertiary academic centre, NY, US | |
| Comparisons | Survey sent from more senior person (medical director) vs. sent from less senior (hospital administrator) | |
| Outcomes | Response after 3 reminders (6 weeks) | |
| Topic | Health (Readiness‐for‐change survey for ICU providers) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire comprised 30 items; 5 minutes to complete The first email and subsequent reminders were sent to each randomised group at the same time. Access to the survey was available for 57 days: three reminders were sent on days 15, 32, and 46. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 3 reminders (6 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hawkins 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Eugene residences listed in the Eugene‐Springfield telephone directory | |
| Comparisons | 1. Department store sponsor; standard 2. Department store sponsor; disclosure 3. Research firm sponsor; standard 4. Research firm sponsor; disclosure 5. University sponsor, standard 6. University sponsor, disclosure | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: women's attitudes to shopping, demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hawley 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Mental health providers, US | |
| Comparisons | No incentive vs. unconditional non‐monetary incentive (therapy magnet) vs. unconditional $1 vs. unconditional $2 vs. unconditional $5 | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (mental health assessment and treatment practices) | |
| Mode of Administration | Postal | |
| Notes | 7‐page questionnaires. Personally addressed and hand‐signed cover letters with first‐class stamps on both the individually addressed outgoing envelope and the return envelope, photographs of children to increase salience and help the survey stand out from other mail, user‐friendly design (e.g. important words were bolded or italicised and each section of the survey was grouped using borders; return address information was placed on both the front and back cover of the survey), two follow‐up mailings including a thank you/reminder postcard sent to the entire sample and a 2nd survey sent to non‐respondents, both of which were also personally addressed and hand‐signed. In addition, a separate postage‐paid postcard was included that respondents could return with their completed address if they wished to receive a summary of the survey findings. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | 6 surveys were undeliverable. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Heaton 1965.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals living in the Philadelphia, Pennsylvania area who had purchased a new 1959 Chevrolet within the previous 12‐16 weeks | |
| Comparisons | 1. Preliminary letter 2. No preliminary letter | |
| Outcomes | Response within 2 weeks | |
| Topic | Non‐health: information on automobile ownership, shopping behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Heerwegh 2005a.
| Study characteristics | ||
| Methods | Random allocation: using SAS RANUNI function | |
| Data | 1st year students at the Katholieke Universiteit Leuven, Belgium | |
| Comparisons | 1. Personalised salutations 2. Non‐personalised salutations |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: adolescents' attitudes towards marriage and divorce | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Method of allocation ascertained through contact with author; age: 17‐20 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Heerwegh 2005b.
| Study characteristics | ||
| Methods | Random allocation: using SAS RANUNI function | |
| Data | 1st year students at the Katholieke Universiteit Leuven, Belgium | |
| Comparisons | 1. Personalised salutations 2. Non‐personalised salutations |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: adolescents' attitudes towards marriage and divorce | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Heerwegh 2006.
| Study characteristics | ||
| Methods | Random allocation: using SAS RANUNI function | |
| Data | Freshmen at the Katholieke Universiteit Leuven, Belgium | |
| Comparisons | 1. Personalised salutations 2. Non‐personalised salutations |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards immigrants and asylum seekers | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Hendrick 1972.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in the city directory (Akron, Ohio) | |
| Comparisons | 1. 1‐page questionnaire; solicitor ingratiate (SI); respondent ingratiate (RI) 2. 1‐page questionnaire, SI; respondent no ingratiate (RNI) 3. 1‐page questionnaire; solicitor no ingratiate (SNI); RI 4. 1‐page questionnaire; SNI; RNI 5. 7‐page questionnaire; SI; RI 6. 7‐page questionnaire; SI; RNI 7. 7‐page questionnaire; SNI; RI 8. 7‐page questionnaire; SNI; RNI | |
| Outcomes | — | |
| Topic | Health: repression ‐ sensitisation personality scale | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hendriks 2001.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | 784 consecutively discharged patients from 8 randomly chosen hospital wards at the Academic Medical Center, Amsterdam | |
| Comparisons | 1. 10‐step evaluation scale (E10) 2. 5‐step evaluation, tick box scale (E5‐B) 3. 5‐step evaluation, circle answer scale (E5‐W) 4. 5‐step satisfaction, tick box scale (S5‐B) 5. 5‐step satisfaction, circle answer scale (S5‐W) | |
| Outcomes | Response period not specified | |
| Topic | Health: satisfaction with hospital care | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Henley 1976.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Fort Worth, Texas | |
| Comparisons | 1. 1 by 4‐inch slip of paper saying 'Please return by April 7th' stapled to the questionnaire 2. No deadline slip | |
| Outcomes | Response within 14 days | |
| Topic | Non‐health: civil issues | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hensley 1974.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Members of the National Forensic League | |
| Comparisons | 1. Outer‐envelope (OE) commemorative Inner‐envelope (IE) commemorative 2. OE commemorative; IE regular 3. OE commemorative; IE metered 4. OE regular; IE commemorative 5. OE regular; IE regular 6. OE regular; IE metered 7. OE metered; IE commemorative 8. OE metered; IE regular 9. OE metered; IE metered | |
| Outcomes | Response period not specified | |
| Topic | Non‐health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Hewett 1974.
| Study characteristics | ||
| Methods | Random allocation: coin toss | |
| Data | Individuals listed in a telephone directory | |
| Comparisons | 1. Hand‐stamped outgoing envelope; hand‐stamped return envelope 2. Hand‐stamped outgoing envelope; first‐class postal permit business‐reply envelope | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Hickey 2021.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated randomisation | |
| Data | A random sample of 500 emergency physicians in Canada | |
| Comparisons | Postal pre‐notification letter vs. no pre‐notification letter | |
| Outcomes | Response after 6 weeks (4 reminders) | |
| Topic | Health (attitudes regarding organ donation) | |
| Mode of Administration | Postal | |
| Notes | 24 questions; 4 sections; double‐sided; 2 sheets; demographic and practice information, attitudes regarding organ donation, acceptability of using the emergency department to promote organ donation and registration and related perceived facilitators and barriers All physicians received an unconditional incentive of a $3 coffee card and an SAE with the survey. In both groups, non‐respondents were sent reminder surveys approximately every 2 weeks for a total of 6 weeks and a special contact using Xpress post during the final contact attempt. Pre‐notification letters were hand‐signed by the principal investigator and sent approximately 1 week prior to the first questionnaire mailout. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated randomisation |
| Allocation concealment? | Yes | Random allocation: computer‐generated randomisation |
| Blinding of participants and personnel | Yes | Personnel were blind but participants were not. |
| Blinding of outcome assessment | Yes | Using blinded outcome assessment, physician responses were analysed. |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 6 weeks (4 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hoffman 1998.
| Study characteristics | ||
| Methods | Random allocation: using terminal digit of study number or house number | |
| Data | Individuals who had previously participated in a campaign to collect blood for a specimen bank | |
| Comparisons | Study 1:
1. Short questionnaire
2. Long questionnaire Study 2: 1. No incentive 2. Newspaper article 3. Pencil 4. Pencil and newspaper article Study 3: 1. Postcard reminder 2. Second questionnaire and letter |
|
| Outcomes | — | |
| Topic | Health: Family history of cancer, reproductive history, medical and vitamin use, history of medical conditions and surgery | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hohwu 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random allocation: method unspecified | |
| Comparisons | Non‐monetary incentive vs. no incentive (Web/tablet) vs. (Web); electronic vs choice (postal/electronic) (Web) vs. (paper/Web); postal vs choice (postal/electronic) (paper) vs. (paper/Web) | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (children's health and welfare) | |
| Mode of Administration | Postal/electronic | |
| Notes | NordChild questionnaire, 73 questions with sub‐questions; the paper version was 28 pages long. All 3200 were invited by mail. Two reminders were mailed to all those who had not responded within 4 and 12 weeks. The Web‐based questionnaire was a multi‐page design using SurveyXact and had the same questions as the paper version. The respondents of the Web‐based questionnaire could answer the questions in several rounds, and submit it after the last question. A 12‐character log‐in code to the Web‐based questionnaire had to be keyed in every time if it was not completed in a single round. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Hopkins 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Professional school and public librarians | |
| Comparisons | 1. $1 incentive
2. No incentive Non‐responders followed‐up after 1 month |
|
| Outcomes | — | |
| Topic | Non‐health: attitudes and practices having a book in Spanish in the library | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Horn 2010.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Parents and carers of children and adolescents involved with CAMHS, Kent, UK | |
| Comparisons | No reminders vs. reminder letter with questionnaire vs. reminder letter with questionnaire plus telephone call to non‐responders 2 weeks after postal reminder | |
| Outcomes | Final response | |
| Topic | Health (experience of Service Questionnaire with Strengths and Difficulties Questionnaire) | |
| Mode of Administration | Postal | |
| Notes | Strengths and Difficulties Questionnaire (SDQ) and Experience of Service Questionnaire (ESQ). Package not described. The experimental interventions were randomly allocated to three Community Child and Adolescent Mental Health Services (CAMHS) teams. These teams were configured to have a broadly equivalent staff mix of mental health nurses, psychologists, psychiatrists and other therapists, weighted in proportion to the population and referrals to each team. CAMHS mapping returns suggest that the teams were not markedly different in the crude case‐mix referred, although Team A served a less deprived population. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method not specified |
| Allocation concealment? | Unclear | Random allocation: method not specified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | No | Randomisation was clustered at CAMHS‐team level, with some differences between populations served that may have been associated with questionnaire response. |
Hornik 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a telephone directory (Chicago, US) | |
| Comparisons | 1. Given time cue of 20 mins 2. Given time cue of 40 mins 3. Not given time cue | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: attitudes to TV advertising | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hornik 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a telephone directory (Chicago, US) | |
| Comparisons | 1. Ingratiation appeal made in pre‐notification telephone call (IA) ‐ male telephone pre‐notified to male respondent (M/M) 2. IA ‐ M/F 3. IA ‐ F/M 4. IA ‐ F/F 5. Polite imperative (PI) ‐ M/M 6. PI ‐ M/F 7. PI ‐ F/M 8. PI ‐ F/F 9. Rhetorical question (RQ) ‐ M/M 10. RQ ‐ M/F 11. RQ ‐ F/M 12. RQ ‐ F/F 13. Statement (S) ‐ M/M 14. S ‐ M/F 15. S ‐ F/M 16. S ‐ F/F 17. No pre‐notification | |
| Outcomes | — | |
| Topic | Non‐health: people's attitudes to television and advertising | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Horowitz 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Faculty members of the University of Maryland (US) | |
| Comparisons | 1. Status of researcher 'professor' (P); ink Signature (I); reproduction photocopied (R‐P) 2. Graduate student (GS); I; R‐P 3. P; non‐Ink (N‐I); R‐P 4. GS; N‐I; R‐P 5. P; I; Reproduction mimeographed (R‐M) 6. GS; I; R‐M 7. P; N‐I; R‐M 8. GS; N‐I; R‐M 9. P; I; R‐T 10. GS; I; R‐T | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: College professors Questionnaire | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Houston 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | New car buyers in Scott County, Iowa (US) | |
| Comparisons | 1. Personalised letter and questionnaire; ballpoint pen incentive 2. Personalised letter and questionnaire; no incentive 3. Non‐personalised; ballpoint pen incentive 4. Non‐personalised; no incentive | |
| Outcomes | — | |
| Topic | Non‐health: sources of information used by the respondent in purchasing their new car | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Houston 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households listed in a telephone directory (Madison) | |
| Comparisons | 1. University sponsor; Social Utility Appeal 2. Commercial sponsor, Social Utility Appeal 3. University sponsor, Help the Sponsor Appeal 4. Commercial sponsor, Help the Sponsor Appeal 5. University sponsor, Egoistic Appeal 6. Commercial sponsor, Egoistic Appeal 7. University sponsor, Combined Appeal 8. Commercial sponsor, Combined Appeal | |
| Outcomes | Response within 1 month | |
| Topic | Non‐health: tap consumer images and behaviour with respect to 5 Madison‐area shopping | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hubbard 1988a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a major midwestern metropolitan area | |
| Comparisons | 1. No incentive 2. Promise of $1 donation to charity of respondent's choice 3. 25 cents cash enclosed 4. $1 cash enclosed 5. Opportunity to win $200 cash prize | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: satisfaction with banking and financial services | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hubbard 1988b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of a major midwestern metropolitan area | |
| Comparisons | 1. Control 2. Pre‐paid 25 cent incentive 3. Pre‐paid $1 incentive 4. Opportunity to win cash prize of $50 5. Opportunity to win cash prize of $100 6. Opportunity to win cash prize of $150 7. Opportunity to win cash prize of $200 8. Opportunity to win cash prize of $250 | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: satisfaction with banking and financial services | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Huck 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students living in residence halls at the University of Tennessee | |
| Comparisons | 1. First mailing with a 25 cent incentive 2. Second mailing (to non‐respondents) with a 25 cent incentive 3. Third mailing (to non‐respondents) with a 25 cent incentive 4. First, second and third mailings without a 25 cent incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Non‐health: Rokeach Dogmatism scale | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Hyett 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residential telephone subscribers | |
| Comparisons | 1. Double‐sided questionnaire
2. Single‐sided questionnaire After 2 weeks, all non‐responders received another questionnaire. 1 week later, all those who still had not responded were followed up by telephone. |
|
| Outcomes | — | |
| Topic | Non‐health: not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Iglesias 2000.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Women aged 70 years and over | |
| Comparisons | 1. 4‐page questionnaire 2. 5‐page questionnaire 3. 7‐page questionnaire | |
| Outcomes | — | |
| Topic | Health: clinical questionnaire, EuroQoL, SF‐12 | |
| Mode of Administration | Postal | |
| Notes | Age: Above 70 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Iglesias 2001.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Women aged 70 years or over selected from 2 general practices in North Yorkshire | |
| Comparisons | 1. Questionnaire with an individual item format 2. Questionnaire with a stem & leaf format | |
| Outcomes | Response period not specified | |
| Topic | Health: SF‐12 | |
| Mode of Administration | Postal. | |
| Notes | Age: Above 70 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Iversen 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients aged 16 years and older registered with a GP, Norway | |
| Comparisons | A pen‐and‐paper questionnaire with the option to answer electronically (mixed) vs. purely electronic protocol | |
| Outcomes | Response after 2 reminders (6 weeks) | |
| Topic | Health (user experiences with healthcare). | |
| Mode of Administration | Postal or electronic | |
| Notes | Norwegian Patient Experiences with General Practitioner Questionnaire; 47 questions on 6 pages. Additional page was included to allow comments. Mailed invitation with both pen‐and‐paper and electronic response options. The invitation included a cover letter describing the purpose of the study, a paper questionnaire, an SAE, and information and a login code to be able to respond electronically. The patients in Group B received an email invitation with an electronic response option only. The email invitation included information about the purpose of the study, a link to the online survey and a login code. Two reminders were sent to non‐respondents in both samples using the same contact mode as the first invitation. The first reminder was sent to both groups around 3 weeks after the first contact. The second reminder was sent around 6 weeks after the first contact. All reminders to Group A were sent by mail and included a new invitation, the paper questionnaire, the SAE and the login code to enable electronic responses. Group B were sent a new email invitation with a link to the survey and a login code in both reminders. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 2 reminders (6 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Jacob 2012.
| Study characteristics | ||
| Methods | Random allocation: assigned a random number to all eligible principals in each strata and then sorted by random number within strata and assigned each quarter to different strata. Randomisation method unclear | |
| Data | High school principals, Michigan, US | |
| Comparisons | Email pre‐notification letter vs. paper pre‐notification letter; unconditional $10 monetary incentive vs. no incentive; electronic vs. postal | |
| Outcomes | Response after 2 reminders (2 weeks) | |
| Topic | Non‐health (online learning and virtual education) | |
| Mode of Administration | Electronic (web‐based) or postal | |
| Notes | 42 questions; 15 mins completion time All four groups were sent a copy of the advance letter (either by mail or email). Surveys sent between 1 (postal) and 2 (email) weeks later. Both groups then received two follow‐up emails/postcards reminding them of the incentive (if they received one) that had been provided and asking them to return the questionnaire. We designed the format of the web survey to match the format of the paper survey as closely as possible; and both versions had identical questions. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unclear |
| Allocation concealment? | Unclear | Random allocation: method unclear |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions (ineligible and undeliverable) reported in full |
| Selective reporting | Yes | Response after 2 reminders (2 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Jacobs 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Public school teachers (Indiana, US) | |
| Comparisons | 1. Short questionnaire; optical scan form
2. Short questionnaire; instructed to respond directly to questionnaire
3. Long questionnaire; optical scan form
4. Long questionnaire; instructed to respond directly to questionnaire Postcard follow up after 2 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes and opinions concerning discipline in the public schools | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jacoby 1990.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals from 10 parliamentary areas (ISSMC questionnaires) Individuals from the electoral register (FPC questionnaires) |
|
| Comparisons | 1. Long questionnaire; sent by ISSMC
2. Long questionnaire; sent by FPC
3. Short questionnaire; sent by ISSMC
4. Short questionnaire; sent by FPC 1. Questionnaire included sensitive question; sent by ISSMC 2. Questionnaire did not include sensitive question; sent by ISSMC 3. Questionnaire included sensitive question; sent by FPC 4. Questionnaire did not include sensitive question; sent by FPC |
|
| Outcomes | — | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
James 1990a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Cable television subscribers (Fairfax County, Virginia, US) | |
| Comparisons | 1. No incentive
2. $0.25
3. $50
4. $1
5. $2 3 follow‐up reminders sent without further monetary incentive at 3‐week intervals |
|
| Outcomes | — | |
| Topic | Non‐health: personal information | |
| Mode of Administration | Postal | |
| Notes | Author contacted: on the third follow up, participants were randomised to receive the questionnaire by first‐class or certified mailing but no data given for results. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
James 1990b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Cable television subscribers who had failed to respond to 2 previous follow‐up attempts | |
| Comparisons | 1. Reminder by certified mail 2. Reminder by first‐class mail | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: personal information | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
James 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of a national trade association of owners of construction subcontracting companies who were not currently enrolled in the association's health insurance programme | |
| Comparisons | 1. No incentive
2. $1 cash
3. $5 cash
4. $5 cheque
5. $10 cheque
6. $20 cheque
7. $40 cheque
8. Promise of $50 1‐page questionnaire, cover letter and business reply envelope. Reminders sent to non‐respondents at 3‐week intervals |
|
| Outcomes | — | |
| Topic | Health: health insurance | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
James 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1154 US physicians who had not responded to two waves of a survey | |
| Comparisons | Monetary incentive vs. non‐monetary incentive; unconditional vs. conditional non‐monetary incentive ($25 cheque); cheque not requiring social security number (SSN) vs. cheque requiring SSN | |
| Outcomes | Final response | |
| Topic | Health (ethical and moral beliefs of physicians) | |
| Mode of Administration | Postal | |
| Notes | 8‐page questionnaire. The mailing of all survey materials in the third wave was co‐ordinated and carried out by our external vendor. Physicians in all four groups received a cover letter printed on Mayo Clinic letterhead signed by the principal investigator; the survey; and a stamped, pre‐addressed return envelope that routed all completed surveys to the Mayo Clinic Survey Research Center. To avoid institutional constraints, we contracted with an external vendor to provide the cash, immediate checks, and promised checks that did not require an SSN. The promised checks requiring an SSN were processed and disbursed by the Mayo Clinic accounting department. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | The mailing of all survey materials in the third wave was co‐ordinated and carried out by our external vendor. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
James 2019.
| Study characteristics | ||
| Methods | Random allocation: generated using STATA | |
| Data | Participants in a trial of occupational therapist‐led home assessment and modification for the prevention of falls (aged over 65 years at risk of falling) | |
| Comparisons | Pen vs. no pen Standard letter vs. letter emphasising to the participant that their questionnaire responses were noted (social incentive text cover letter) | |
| Outcomes | First response | |
| Topic | Health (falls in the elderly) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. An unconditional £5 note was included with the questionnaire for all participants. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: generated using STATA |
| Allocation concealment? | Yes | Random allocation: generated using STATA |
| Blinding of participants and personnel | Yes | Participants were blind to their participation. Research administrators and research team members posting the questionnaire packs were not blind to the intervention; however, administrators who recorded the outcome data were blind to allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Jamtvedt 2008.
| Study characteristics | ||
| Methods | Random allocation: block randomisation by computer‐generated table | |
| Data | Norwegian physiotherapists from private practice | |
| Comparisons | 1. Dark chocolate 2. Control group |
|
| Outcomes | Response period within 9 months | |
| Topic | Health: treatment provided to 1 patient with osteoarthritis of knee through 12 treatment sessions | |
| Mode of Administration | Postal | |
| Notes | Randomisation was generated by Doris Tove Kristoffersen, who was not involved with any other aspect of the trial. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 9 months reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Jenkinson 2003.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Recently discharged patients from 2 English inner city NHS Trusts | |
| Comparisons | 1. 4‐page questionnaire 2. 12‐page questionnaire |
|
| Outcomes | Response after 4 weeks (2 reminders) | |
| Topic | Health: Picker Patient Experience Questionnaire | |
| Mode of Administration | Postal | |
| Notes | Shorter (4‐page) vs. longer (12‐page) questionnaire The four‐page questionnaire contained the PPE‐15 nested within 31 questions covering demographics, health status and other aspects of patient experience. The 12‐page questionnaire contained the PPE‐15 nested within 108 questions; i.e. almost three and a half times as many items as on the four‐page version. Reminders were sent out after 2 weeks if no reply had been received; a second questionnaire was sent after a further 2 weeks if questionnaires remained unreturned. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 4 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Jensen 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Female graduates from the doctoral program in education from a private west‐coast university (US) | |
| Comparisons | 1. Open‐ended questions first; closed questions next; demographic questions last
2. Open; demographic; closed
3. Closed; open; demographic
4. Closed; demographic; open
5. Demographic; open; closed
6. Demographic; closed; open Reminders sent at 6 and 12 weeks. Some graduates were living out of the country at the time of the study. They were sent postal vouchers and an envelope instead of a stamped envelope on the initial mailing and first follow‐up. On the second follow‐up, US citizens received a telephone call while overseas received another postal mailing. |
|
| Outcomes | — | |
| Topic | Non‐health: Graduate school experiences | |
| Mode of Administration | Postal | |
| Notes | Age: 31‐65; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jepson 2005a.
| Study characteristics | ||
| Methods | Random allocation: using random number generated in Excel | |
| Data | US Primary care physician members of the American Medical Association | |
| Comparisons | 1. Word count ‐ 849 2. Word count ‐ 1145 3. Word count ‐ 1163 4. Word count ‐ 1164 5. Word count ‐ 1215 6. Word count ‐ 1216 7. Word count ‐ 1234 8. Word count ‐1423 9. Word count ‐ 1424 10. Word count ‐ 1447 11. Word count ‐ 1449 12. Word count ‐ 1461 13. Word count ‐ 1462 14. Word count ‐ 1494 15. Word count ‐ 1496 16. Word count ‐ 1519 17. Word count ‐ 1520 18. Word count ‐ 1560 19. Word count ‐ 1561 20. Word count ‐ 1703 21. Word count ‐ 1706 22. Word count ‐ 1737 23. Word count ‐ 1744 24. Word count ‐ 1756 25. Word count ‐ 1776 26. Word count ‐ 1785 27. Word count ‐ 1788 28. Word count ‐ 1807 29. Word count ‐ 1855 30. Word count ‐ 1867 |
|
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards cost quality trade‐offs in clinical practice | |
| Mode of Administration | Postal | |
| Notes | Short length: from word count 849 ‐ 1234; long length: from word count 1423 ‐ 1867; method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Jepson 2005b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | US Primary care physician members of the American Medical Association | |
| Comparisons | 1. Word count ‐ 564 2. Word count ‐ 574 3. Word count ‐ 649 4. Word count ‐ 703 5. Word count ‐ 711 6. Word count ‐ 715 7. Word count ‐ 719 8. Word count ‐730 9. Word count ‐ 749 10. Word count ‐ 753 11. Word count ‐ 754 12. Word count ‐ 762 13. Word count ‐ 782 14. Word count ‐ 849 15. Word count ‐ 905 16. Word count ‐ 988 |
|
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards cost quality trade‐offs in clinical practice | |
| Mode of Administration | Postal | |
| Notes | Short length: from word count 564 to 730; long length: from word count 749 to 905; method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Jobber 1983.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Textile companies listed in the Kompass‐Directory of UK Companies and 'Times Top 500' | |
| Comparisons | 1. Prior letter; white questionnaire 2. Prior letter; blue questionnaire 3. No prior letter; white questionnaire 4. No prior letter; blue questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: information about the marketing strategies employed by the company | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jobber 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Senior marketing executives | |
| Comparisons | 1. Cover letter contained offer of a free copy of results as the final paragraph of the body of the letter 2. Same cover letter but offer made in typed postscript 3. Same cover letter but offer made in handwritten postscript 4. Cover letter with no offer | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: explore the design and extent of implementation of marketing information system | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jobber 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Building Society chief executives | |
| Comparisons | 1. 20 pence incentive; no booklet 2. 20 pence incentive; booklet explaining survey included 3. No incentive; no booklet 4. No incentive; booklet explaining survey included | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: ascertain management practices, and contextual and structural characteristics of societies | |
| Mode of Administration | Postal | |
| Notes | Number of subjects allocated to each intervention group ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jobber 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Industrial goods companies | |
| Comparisons | 1. Short questionnaire; 1‐sided printing
2. Short questionnaire; 2‐sided printing
3. Long questionnaire; 1‐sided printing
4. Long questionnaire; 2‐sided printing The long questionnaire comprised 2 different versions of a short questionnaire. The 2 versions were allocated randomly between treatments. |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: selling approach and orientations used by the sample firms, evaluate the sale persons, size of firm, industry category, number of sales persons employed | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jobber D 1985.
| Study characteristics | ||
| Methods | Random allocation: systematic random sampling | |
| Data | Quality control managers of textile companies randomly selected from a directory of UK companies | |
| Comparisons | 1. No pre‐notification 2. Telephone pre‐notification | |
| Outcomes | Response prior to second wave of the experiment | |
| Topic | Non‐health: quality management systems used by UK textile companies | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Johansson 1997a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Norwegian citizens aged 16‐79 years | |
| Comparisons | 1. No reward offered
2. Reward offered 1 reminder sent after 4 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Health: Quantitative Food Frequency Questionnaire (QFFQ) | |
| Mode of Administration | Postal | |
| Notes | Mean age: 42‐47 | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Johansson 1997b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Norwegian citizens aged 16‐79 years | |
| Comparisons | 1. No reward offered
2. Reward offered 1 reminder sent after 4 weeks |
|
| Outcomes | Response period not specified | |
| Topic | Health: Quantitative Food Frequency Questionnaire (QFFQ) | |
| Mode of Administration | Postal | |
| Notes | Mean age: 42‐47 | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Johansson 1997c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Norwegian citizens aged 16‐79 years who had not responded to a questionnaire | |
| Comparisons | 1. Follow‐up by telephone 2. Follow‐up by post | |
| Outcomes | Response period not specified | |
| Topic | Health: Quantitative Food Frequency Questionnaire (QFFQ) | |
| Mode of Administration | Postal | |
| Notes | Mean age: 42‐47 | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
John 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Cosmetologists aged 22 to 36 years | |
| Comparisons | 1. $1 incentive in first mailing
2. $1 incentive in second mailing
3. No incentive 2‐page questionnaire, cover letter, survey fact sheet and stamped addressed envelope. Reminder postcard sent 1 week after first mailing |
|
| Outcomes | Response period not specified | |
| Topic | Health: screening questions ‐ recent health problems, reproductive history; outcome of the most recent pregnancy | |
| Mode of Administration | Postal | |
| Notes | Age: 22‐36; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Joinson 2005a.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Students at the Open University, UK | |
| Comparisons | 1. Salutation ‐ 'Dear Student' 2. Salutation ‐ 'Dear Open University Student' 3. Salutation ‐ 'Dear Forename' (e.g. Dear John) 4. Salutation ‐ 'Dear Forename Surname' (e.g. Dear John Doe) |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: volunteering to become a member of a survey panel (PRESTO) | |
| Mode of Administration | Electronic: email | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Joinson 2005b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Students at the Open University, UK | |
| Comparisons | 1. Salutation ‐ 'Dear Student' 2. Salutation ‐ 'Dear Open University Student' 3. Salutation ‐ 'Dear Forename' (e.g. Dear John) 4. Salutation ‐ 'Dear Forename Surname' (e.g. Dear John Doe) |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: inviting the existing panel members to exit the panel | |
| Mode of Administration | Electronic: email | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Joinson 2005c.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Students at the Open University, UK | |
| Comparisons | 1. Salutation ‐ 'Dear Student' 2. Salutation ‐ 'Dear Forename' (e.g. Dear John) 3. Salutation ‐ 'Dear Forename Surname' (e.g. Dear John Doe) 4. High Power ‐ "From Professor (name), Pro‐Vice chancellor, (strategy, planning and partnerships), the OU 5. Neutral Power ‐ "From (name), (strategy, planning and partnerships), the OU |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: inviting the panel members to complete the survey | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Joinson 2007a.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Members of an online student panel at the Open University, UK | |
| Comparisons | 1. High Power ‐ "From Professor (name), Pro‐Vice chancellor, (strategy, planning and partnerships), the OU 2. Neutral Power ‐ "From (name), (strategy, planning and partnerships), the OU 3. Salutation ‐ 'Dear Forename' (e.g. Dear John) 4. Salutation ‐ 'Dear Presto panel member' |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: socioeconomic status | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author; mean age: 41.8 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Joinson 2007b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Members of an online student panel at the Open University, UK | |
| Comparisons | 1. Personalised URL (unique URL with identifier encoded in the link) 2. Authentication required (URL requires logon to access the survey) |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: part‐time student costs and fees | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author; mean age: 43.6 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Jones 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals who had planned group conventions and/or meetings | |
| Comparisons | 1. Science appeal (SA); commemorative stamp (CS); J&L sponsor (J&L) 2. SA; CS; University sponsor (US) 3. SA; CS; Government sponsor (GS) 4. SA; regular stamp (RS); J&L 5. SA; RS; US 6. SA; RS; GS 7. SA; business‐reply envelope (BR); J&L 8. SA; BR; US 9. SA; BR; GS 10. User appeal (UA); CS; J&L 11. UA; CS; US 12. UA; CS; GS 13. UA; RS; J&L 14. UA; RS; US 15. UA; RS; GS 16. UA; BR; J&L 17. UA; BR; US 18. UA; BR; GS 19. Resort park appeal (RA); CS; J&L 20. RA; CS; US 21. RA; CS; GS 22. RA; RS; J&L 23. RA; RS; US 24. RA; RS; GS 25. RA; BR; J&L 26. RA; BR; US 27. RA; BR; GA | |
| Outcomes | Response within 6 weeks | |
| Topic | Non‐health: characteristics of the group, respondent attitudes towards meeting facilities, demographic factors | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Jones 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adult patients admitted for treatment between 14/09/98 and 12/12/98 | |
| Comparisons | 1. No incentive 2. $2 3. $5 4. SF‐36 5. SF‐12 6. MH‐5 7. MH‐1 |
|
| Outcomes | Response period not specified | |
| Topic | Health: health status survey | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Junghans 2005.
| Study characteristics | ||
| Methods | Random allocation: using minimisation software | |
| Data | 2 general practices in England | |
| Comparisons | 1. Opt‐in (asked to actively signal willingness to participate in research) 2. Opt‐out (contacted repeatedly unless they signalled unwillingness to participate) |
|
| Outcomes | Response period within 2 weeks | |
| Topic | Health: patients with angina | |
| Mode of Administration | Postal | |
| Notes | The identity of the trial was kept in a sealed envelope and was known only to the research assistant. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Juszczak 2021.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Parents of preterm babies from participating neonatal units, UK | |
| Comparisons | Conditional non‐monetary incentive (£15 voucher) vs. unconditional non‐monetary incentive (£15 voucher) | |
| Outcomes | Response after one reminder | |
| Topic | Health (neurodevelopmental disability at 2 years of age) | |
| Mode of Administration | Mixed | |
| Notes | Questionnaire not described. Questionnaires were sent to all parents where infant(s) vital status and address could be confirmed by both post and as a link to an online submission form via email and text message, where these contact details were available. Parents were also reminded to complete the questionnaire via text and/or email during the follow‐up window. All parents were offered the option of completing the questionnaire online or, as a last resort, via telephone. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | SIFT office staff at the NPEU Clinical Trials Unit were aware of allocation due to the nature of the interventions and the practicalities involved in sending out the letters and the vouchers. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Kahle 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Psychiatrists and clinical psychologists | |
| Comparisons | Experiment 1:
1. Dillman's 3‐wave mailing design
2. As (1) except first 2 waves received non‐profit bulk rate permit number printed where stamp had been
3. As (2) except pre‐printed labels used to address envelopes rather than addresses typed individually on envelopes Experiment 2: As experiment 1 but in final wave questionnaire sent by: 1. Certified mail 2. First‐class mail |
|
| Outcomes | Response period not specified | |
| Topic | Health: involuntary civil commitments | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kalafatis 1995.
| Study characteristics | ||
| Methods | Random allocation: using random number generation | |
| Data | Danish participants in a non‐price‐based promotion that utilised an American sporting theme | |
| Comparisons | 1. No incentives 2. Unconditional 5% value of coupon 3. Unconditional 10% value of coupon 4. Unconditional 15% value of coupon 5. Conditional 5% value of coupon 6. Conditional 10% value of coupon 7. Conditional 15% value of coupon 8. Free gift 9. No free gift |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: sports ‐ promotional offers, viewing patterns of sports programmes, shopping habits of sports goods and perceptions of different sports | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kalantar 1999.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Residents of Western Sydney, Australia | |
| Comparisons | 1. Long questionnaire (7 pages) 2. Short questionnaire (1 page) 3. Scratch lottery worth $1 to win up to $2500 4. No lottery |
|
| Outcomes | Response period not specified | |
| Topic | Health: bowel function and faecal incontinence | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Kaplan 1970a.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Residents of Boston and Brockton, Massachusetts, USA | |
| Comparisons | 1. Long questionnaire 2. Short questionnaire 3. Impersonal letter (no inside address and the salutation is 'Dear Madam') 4. Personal letter (with complete address and the salutation is 'Dear Mrs. name') 5. Stamped return envelope 6. Franked return envelope 7. Non‐specific signer 8. Jewish signer 9. Irish signer |
|
| Outcomes | Response period not specified | |
| Topic | Health: reproductive history and the use of oral contraceptives | |
| Mode of Administration | Postal | |
| Notes | Age: 20‐70 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Kaplan 1970b.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Residents of Boston and Brockton, Massachusetts, USA | |
| Comparisons | 1. Irish signer 2. Irish, Professor signer 3. Non‐specific signer |
|
| Outcomes | Response period not specified | |
| Topic | Health: reproductive history and the use of oral contraceptives | |
| Mode of Administration | Postal | |
| Notes | Age: 20‐70 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Kaplowitz 2004.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Residential and agricultural landowners in the Sycamore creek watershed, USA | |
| Comparisons | 1. Survey instrument ‐ colour 2. Survey instrument ‐ black and white |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: homeowner preferences for watershed management practices | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Kasprzyk 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Sample of the general internists listed on the American Medical Association files who spend time on direct patient care, deal with STD diagnosis and have a listed mailing address | |
| Comparisons | 1. First‐class mailing; no incentive 2. First‐class mailing; $15 cash 3. First‐class mailing; $25 cash 4. FedEx mailing; no incentive 5. FedEx mailing; $15 cash 6. FedEx mailing; $25 cash | |
| Outcomes | Response after final reminder mailing, 8 weeks after initial survey | |
| Topic | Health: physician and practice characteristics, STD diagnosis. treatment and control practice, opinions about STD reporting requirements and partner notification | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kawash 1971.
| Study characteristics | ||
| Methods | Random allocation: using table of random numbers | |
| Data | Faculty members of University of Illinois | |
| Comparisons | 1. Personal signature 2. Mimeographed facsimile |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards audiovisual instructional materials | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Keating 2008.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Physicians caring for patients in the Cancer Care Outcomes Research and Surveillance (CanCORS) Consortium | |
| Comparisons | Lower non‐monetary incentive ($20 cheque) vs. higher non‐monetary incentive ($50 cheque) | |
| Outcomes | Response after 13 weeks (2 postal reminders and one phone call) | |
| Topic | Health (physicians' beliefs regarding treatments, their style of practice, barriers to accessing care for their patients, practice characteristics, financial arrangements, and demographics) | |
| Mode of Administration | Postal (optional online response) | |
| Notes | 10‐13 pages, 10‐15 minutes to complete. Cover letter was printed on letterhead from the Northern California Cancer Center and was signed by the centre's Chief Scientific Officer and co‐signed by the Director of the National Cancer Institute and the Medical Director of the American Cancer Society. Each packet also included one or more letters of endorsement matched to the recipient's specialty. The surveys were mailed by priority mail with a stamped, pre‐addressed return envelope. Physicians were also given the option of responding to the survey via a secure website, after logging in with a username and password. Three weeks after the initial mailing, another copy of the survey and cover letter (without another cheque) was sent by first‐class mail to all non‐responders. Approximately 2 weeks later, a research assistant placed phone calls to the offices of non‐responding physicians to verify that the survey had been received, encourage completion, and offer to mail or fax a replacement questionnaire. Up to 10 attempts were made to reach each non‐responding physician. After another 6‐8 weeks, a third mailing of the survey and cover letter was sent to non‐responding physicians with another incentive (of the same amount as the first). | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 13 weeks (2 postal reminders and one phone call) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Keding 2016a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Consenting participants within the Acupuncture and Depression (ACUDep) trial from primary care practices in Yorkshire and the North of England | |
| Comparisons | Pre‐notification SMS vs. no pre‐notification | |
| Outcomes | Response after 13 weeks | |
| Topic | Health (quality of life measures) | |
| Mode of Administration | Postal | |
| Notes | 12 A4 pages long; contained quality of life measures, including Patient Health Questionnaire 9 (PHQ‐9) and EuroQoL. Pre‐notification text messages were sent on the day the postal questionnaire was sent out to participants. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants did not know that they were part of an RCT of text messaging so they were blind to the study hypothesis. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 13 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Keding 2016b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Consenting participants within the Acupuncture and Depression (ACUDep) trial from primary care practices in Yorkshire and the North of England. | |
| Comparisons | Pre‐notification SMS vs. post‐notification | |
| Outcomes | Response after 13 weeks. | |
| Topic | Health (quality of life measures) | |
| Mode of Administration | Postal | |
| Notes | 12 A4 pages long; contained quality of life measures, including Patient Health Questionnaire 9 (PHQ‐9) and EuroQoL. Pre‐notification text messages were sent on the day the postal questionnaire was sent out to participants. Post‐notification text messages were sent 4 days after the postal questionnaire was sent out. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants did not know that they were part of an RCT of text messaging so they were blind to the study hypothesis. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 13 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Keding 2016c.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Consenting participants within the Acupuncture and Depression (ACUDep) trial from primary care practices in Yorkshire and the North of England. | |
| Comparisons | Post‐notification SMS vs. no notification | |
| Outcomes | Response after 13 weeks. | |
| Topic | Health (quality of life measures) | |
| Mode of Administration | Postal | |
| Notes | 12 A4 pages long; contained quality of life measures, including Patient Health Questionnaire 9 (PHQ‐9) and EuroQol. Post‐notification text messages were sent 4 days after the postal questionnaire was sent out. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants did not know that they were part of an RCT of text messaging so they were blind to the study hypothesis. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 13 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Keeter 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Attorneys, clinical social workers, college and university faculty, staff and students, employees and employers in business organisations and a sample of physicians | |
| Comparisons | 1. White questionnaire 2. Pink questionnaire 3. Green questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Health: purchase of major medical equipment Non‐health: housing market, parking and ridesharing, workload, distribution of time, attitudes |
|
| Mode of Administration | Postal | |
| Notes | Results of 7 different studies all examining the same intervention over a 14‐month period | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kenyon 2005.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Mothers of the MRC ORACLE Trial that evaluated the use of antibiotics to improve neonatal outcome after preterm labour/preterm rupture of the membrane | |
| Comparisons | 1. £5 voucher 2. No voucher |
|
| Outcomes | Response period not specified | |
| Topic | Health: child's health and development | |
| Mode of Administration | Postal | |
| Notes | 12 pages, A4 size Letter with the questionnaire was individualised for the child concerned and the parents. Envelope was franked, including an SAE. Six weeks after the first questionnaire, a reminder was sent to those who had not responded and included a questionnaire and a £5 voucher incentive (or not) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Keown 1985a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Japanese business executives | |
| Comparisons | 1. $1 incentive 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards business risk | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Keown 1985b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Business executives (Hong Kong) | |
| Comparisons | 1. $1 incentive 2. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards business risk | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kephart 1958.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Women who had passed their Pennsylvania State Nursing Board exams | |
| Comparisons | 1. Regular stamp; no preview or follow‐up 2. Preview sent 1 week prior to questionnaire 3. Follow‐up (duplicate questionnaire, letter and return envelope) 4. Preview and follow‐up 5. Airmail stamp 6. Special delivery mail 7. Incentive of a penny 8. Incentive of a nickel 9. Incentive of a dime 10. Incentive of a quarter | |
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards nursing profession | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kereakoglow 2013.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Oncology physicians and nurses | |
| Comparisons | Glossy paper with colour vs. standard paper without colour | |
| Outcomes | Response after 8 weeks (3 reminders) | |
| Topic | Health (practices, preferences, and attitudes surrounding the concept of offering results of clinical trials to study participants) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Each study packet included a cover letter, an SAE, outer envelope, and questionnaire. The cover letter, explaining the primary purpose of the study was printed on Cancer and Leukemia Group B (CALGB) research group letterhead to encourage increased response from the CALGB members; To maximise response, facsimile (fax) and electronic mail (email) reminders were sent 3 weeks after the initial materials were sent. Clinicians who did not return the survey within 4 weeks of the initial mailing were contacted, once again, by telephone, email, or fax. Clinicians who had not responded by 8 weeks following the initial mailing and who were able to be located were resent the study materials (either enhanced or standard, according to their original randomisation allocation). | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | The potential participants did not know there were two versions of the survey, and did not know they were randomised to receive one of the versions. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 8 weeks (3 reminders) reported in full |
| Other sources of bias | No | Results potentially confounded between glossy vs. standard paper and colour vs. white paper |
Kerin 1976.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Corporate presidents from 'Fortune 500' firms | |
| Comparisons | 1. Individual cover letter; altruistic appeal; stamp on return envelope 2. Individual; altruistic; no stamp 3. individual; egoistic appeal; stamp 4. individual; egoistic; no stamp 5. Form cover letter; altruistic; stamp 6. Form cover letter; altruistic; no stamp 7. Form; egoistic; stamp 8. Form; egoistic; no stamp | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: product recall practices | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kerin 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Senior marketing executives | |
| Comparisons | 1. Offered results 2. Not offered results | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: interaction between sales and advertising functions in the design and execution of promotion strategy | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kernan 1971.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Cincinnati | |
| Comparisons | 1. Personalised address; first‐class 2. Personalised address; bulk rate 3. Occupant address; first‐class 4. Occupant address; bulk rate | |
| Outcomes | Response within 3 weeks | |
| Topic | Non‐health: community's general interest in new sports stadium | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Khadjesari 2011a.
| Study characteristics | ||
| Methods | Random allocation: Computer‐generated randomisation in Java | |
| Data | Participants in the 'Down Your Drink' online trial of a Web‐based intervention to reduce alcohol consumption | |
| Comparisons | Conditional non‐monetary incentive (£5 Amazon voucher) vs. £5 donation to charity vs. entry in a £250 prize draw vs. no incentive | |
| Outcomes | Response after 1 reminder | |
| Topic | Health (alcohol consumption, dependence and mental health) | |
| Mode of Administration | Electronic | |
| Notes | Participants were emailed a request to provide follow‐up data. The email contained a URL to the study questionnaires, stressed the importance of providing follow‐up data, and conveyed gratitude to participants for providing this information. The first incentive study was undertaken with participants in the DYD pilot who did not respond to an email invitation to provide follow‐up data within 1 week at its final (3‐month) follow‐up point. The second study was undertaken with all participants in the main DYD trial at its final (12‐month) follow‐up point during a defined time period of approximately 9 months. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated randomisation in Java |
| Allocation concealment? | Yes | Random allocation: computer‐generated randomisation in Java |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 1 reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Khadjesari 2011b.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated randomisation in Java | |
| Data | Participants in the 'Down Your Drink' online trial of a Web‐based intervention to reduce alcohol consumption | |
| Comparisons | Conditional non‐monetary incentive (£10 Amazon voucher) vs. no incentive | |
| Outcomes | Response after 1 reminder | |
| Topic | Health (alcohol consumption, dependence and mental health) | |
| Mode of Administration | Electronic | |
| Notes | Participants were emailed a request to provide follow‐up data. The email contained a URL to the study questionnaires, stressed the importance of providing follow‐up data, and conveyed gratitude to participants for providing this information. The first incentive study was undertaken with participants in the DYD pilot who did not respond to an email invitation to provide follow‐up data within 1 week at its final (3‐month) follow‐up point. The second study was undertaken with all participants in the main DYD trial at its final (12‐month) follow‐up point during a defined time period of approximately 9 months. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated randomisation in Java |
| Allocation concealment? | Yes | Random allocation: computer‐generated randomisation in Java |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 1 reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Kilsdonk 2015.
| Study characteristics | ||
| Methods | Random allocation: computer generated | |
| Data | 750 adult childhood cancer survivors, NL | |
| Comparisons | Web‐based vs. choice (web or paper‐based questionnaire) at first contact vs. choice (web or paper‐based questionnaire) at second contact vs. choice (web or paper‐based questionnaire) at third contact | |
| Outcomes | First response and response after one reminder | |
| Topic | Health (medical history, disease symptoms, medication use, lifestyle, and quality of life). | |
| Mode of Administration | Postal and web‐based | |
| Notes | The questionnaires for male and female cancer survivors contained 97 and 112 questions, respectively. All CCSs received a postal package including a cover letter signed by the local physician responsible for CCSs follow‐up care in which the login procedure for the Web‐based questionnaire was explained and login details were given. An information sheet, an informed consent form, a refusal form, and a pre‐stamped return envelope were included. Paper‐based questionnaires were added to the invitation at various time points depending on the study arm. CCSs either received the paper‐based questionnaire at first contact (study arm 3), second contact (study arm 2), or third contact (study arm 1). All CCSs receiving the Web‐based questionnaire at any of the time points had the option to apply for a copy of the paper‐based questionnaire by contacting the study co‐ordinator through email or telephone. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response and response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Kindra 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households listed in a telephone directory (Montreal, Canada) | |
| Comparisons | 1. Pre‐contact; lottery incentive 2. No pre‐contact; lottery incentive 3. Pre‐contact; no lottery incentive 4. No pre‐contact; no lottery incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: elicit consumer response to product advertising | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
King 1978.
| Study characteristics | ||
| Methods | Random allocation: systematic sampling procedure with random start | |
| Data | Registered bank holding companies | |
| Comparisons | 1. Cover letter most personalised 2. Cover letter least personalised | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Koloski 2001.
| Study characteristics | ||
| Methods | Random allocation: random block procedure | |
| Data | People aged 18 years and above listed on the 1996 Local Government electoral roll, Penrith, Australia | |
| Comparisons | 1. Short (28‐page) questionnaire; lottery card included 2. Short questionnaire; no lottery card 3. Long questionnaire (32 pages); lottery card included 4. Long questionnaire; no lottery card | |
| Outcomes | Response after 8 phases of follow‐up | |
| Topic | Health: questions on common health problems especially on stomach and bowel, Delusions Symptoms States Inventory, SF‐12 | |
| Mode of Administration | Postal | |
| Notes | Age: 41.9‐46.6 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Koloski 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in a population‐based study on functional gastrointestinal disorders in the community, Australia | |
| Comparisons | Unconditional non‐monetary incentive ($1 lottery ticket) vs. conditional non‐monetary incentive ($1 lottery ticket) vs. no incentive | |
| Outcomes | Response after the first mail out and after week‐1 reminder letter | |
| Topic | Health (gastrointestinal disorders) | |
| Mode of Administration | Postal | |
| Notes | 32‐page questionnaire. The cover letter included several elements designed to increase the subjects' personal interest in the study. These included a personal salutation, a scanned version of the investigator's handwritten signature, an explanation of the nature and importance of the research, and reassurance of confidentiality. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported; the sample size was reduced by 69 ineligibles (n = 50 return to senders and n = 19 deaths). |
| Selective reporting | Yes | Response after the first mail out and after week 1 reminder letter reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Koo 1995.
| Study characteristics | ||
| Methods | Random allocation: random function in Microsoft Excel programme | |
| Data | Girls recruited by volunteers from the Canadian Cancer Society | |
| Comparisons | 1. Real signature on cover letter 2. Printed signature | |
| Outcomes | Response within 105 days | |
| Topic | Health: dietary and lifestyle determinants of the onset of menarche | |
| Mode of Administration | Postal | |
| Notes | Allocation was not concealed; age: 7.5‐14.9 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Koo 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Girls recruited by volunteers from the Canadian Cancer Society who had not responded in a previous study | |
| Comparisons | 1. Regular reminder letter 2. Reminder letter with telephone reminder indicated 3. Reminder letter with telephone interview indicated | |
| Outcomes | Response within 16 days (prior to telephone interview) | |
| Topic | Health: dietary and lifestyle determinants of the onset of menarche | |
| Mode of Administration | Postal | |
| Notes | Age: 8.7‐16.2 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kost 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2228 volunteers from ResearchMatch (US research volunteer registry) | |
| Comparisons | Ultrashort vs. short vs. long Conditional non‐monetary incentive (smaller $10 Amazon voucher vs. larger $20) | |
| Outcomes | e‐login and e‐completed | |
| Topic | Non‐health (understanding of research participant experience ‐ motivation and satisfaction) | |
| Mode of Administration | Web survey | |
| Notes | Research Participant Perception Survey, RPPS: ultrashort (13 questions), short (25 questions), and long (72 questions) Volunteers were randomised to receive an email from the investigator providing a personalised hyperlink to one of the 3 surveys. Individuals clicking on the survey link encountered informed consent information including an estimate of the time required to complete the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Kropf 2005.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of the Health Maintenance Organizations (HMOs) in Maryland | |
| Comparisons | 1. $5 incentive 2. No incentive 3. Cover letter ‐ norms of co‐operation (answering the survey would help many other people) 4. Cover letter ‐ norms of self‐interest (co‐operation would help the survey respondent himself or herself) |
|
| Outcomes | Response period not specified | |
| Topic | Health: healthcare and other current issues | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kurth 1987.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Employees of the Maricopa Community Colleges with email accounts | |
| Comparisons | 1. Type‐written; sensitive question 2. Type‐written; no sensitive question | |
| Outcomes | Response within 30 days | |
| Topic | Non‐health: supervisory management | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kuskowska‐Wolk 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Women aged 40‐70 years from 2 medium‐sized towns in Uppsala Health Care Region invited for mammography over the period 13 October 1986 to 20 March 1987 | |
| Comparisons | 1. Increasing order of food frequencies; no column on portion sizes; no extra page of questions 2. Decreasing order of food frequencies; no column on portion sizes; no extra page of questions 3. Increasing order of food frequencies; column on portion sizes; no extra page of questions 4. Decreasing order of food frequencies; column on portion sizes; no extra page of questions 5. Increasing order of food frequencies; no column on portion sizes; extra page of questions 6. Decreasing order of food frequencies; no column on portion sizes; extra page of questions 7. Increasing order of food frequencies; column on portion sizes; extra page of questions 8. Decreasing order of food frequencies; column on portion sizes; extra page of questions | |
| Outcomes | Response period not specified | |
| Topic | Health: Food Frequency Questionnaire | |
| Mode of Administration | Postal | |
| Notes | Age: 54.9‐55.6 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Kypri 2003.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Tertiary students at the University of Otago | |
| Comparisons | 1. Ballpoint pen worth $0.50 2. Pen + cookie voucher worth $1 3. Pen + lunch voucher worth $5 4. Pen + lunch voucher worth $5 on completion of the survey |
|
| Outcomes | Response after one week (1 reminder) | |
| Topic | Health (alcohol consumption) | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Age: 16‐29 years; mainly females A personally addressed and signed letter on university letterhead was mailed to sampled students, inviting them to participate in a confidential Alcohol Use Survey via the Web. The letter notified the recipients that in 2 days time an email message would be sent to their student email address, and that a hypertext link contained in the message, when clicked, would open their computer web browser at the site hosting the survey. One week after the first email message was sent, the survey database was checked to determine whether the student had responded. A polite personalised reminder email was sent to students who had not yet responded. This also contained a hypertext link to the web questionnaire in case the previous email had been deleted. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method not specified |
| Allocation concealment? | Unclear | Random allocation: method not specified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after one week (1 reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Kypri 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Individuals drawn at random from Maori electoral roll and individuals drawn at random from general NZ electoral roll | |
| Comparisons | Conditional non‐monetary incentive (entry into prize draw for a $500 supermarket voucher) vs. no incentive; conditional non‐monetary incentive ($5 donation to charity) vs. no incentive | |
| Outcomes | First response | |
| Topic | Health (alcohol consumption and problems) | |
| Mode of Administration | Postal | |
| Notes | 8‐page booklet containing 44 questions requiring tickbox (or checkbox) or short‐text responses. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
La Garce 1995.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Goodyear tyre and rubber dealers | |
| Comparisons | 1. Standard questionnaire printed in black and white 2. Standard questionnaire printed in blue and yellow 3. User‐friendly format questionnaire printed in black and white 4. User‐friendly format questionnaire printed in blue and yellow | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: industry | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Labarere 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 400 people recently discharged from hospital | |
| Comparisons | 1. Postal questionnaire, no follow‐up 2. Postal questionnaire with follow‐up | |
| Outcomes | Response within 2 months | |
| Topic | Health: patient satisfaction | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Labrecque 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Service customers of a marina | |
| Comparisons | 1. Owner's signature (OS); personalised (P); commemorative stamp (CS) 2. Service manager's signature (SMS); P; CS 3. OS; not personalised (NP); CS 4. SMS; NP; CS 5. OS; P; No CS 6. SMS; P; No CS 7. OS; NP; No CS 8. SMS; NP; No CS | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: reaction of customers to the performance of its service department | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Lagerros 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 637 people from the population register at Statistics Sweden who had agreed to participate in a study on physical activity | |
| Comparisons | Postal vs. Web vs. SMS | |
| Outcomes | Final response after 1‐3 reminders | |
| Topic | Health (physical activity) | |
| Mode of Administration | Postal/Web/SMS | |
| Notes | 4 questions (body weight, height and two questions on physical activity). In the postal group, the four questions were mailed to their home address. In the web group, an email was sent to the participant with a link to a website together with a username and a password. The participants were asked to log on to the website and answer the four questions. In the SMS group, the participant got one initial SMS explaining that she or he would soon receive the questions; after a few minutes, the four questions were sent in four separate SMS messages with 5 to 10 mins between them. All non‐responders in the three groups were reminded in a sequence that was considered appropriate for the technique. Thus, one reminder was sent out to the postal group (a letter after 3 weeks), three reminders were sent out to the web group (emails 2, 3 and 6 days after the first email, respectively), and two reminders were sent out to the SMS group (an SMS 1 and 2 days after the first SMS, respectively). | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Langenderfer‐Magruder 2020.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated random numbers using Microsoft Excel | |
| Data | Non‐respondents to Wave 2 of the Florida Study of Professionals for Safe Families (a longitudinal study of child welfare workforce retention), US. | |
| Comparisons | SMS reminder including web‐survey link (condition 2) vs. SMS reminder without survey link (condition 1) vs. SMS reminder with offer of SMS including web‐survey link (condition 3) | |
| Outcomes | Response after 3 reminders (44 days) | |
| Topic | Health (worker personal or organisational characteristics that may impact job satisfaction and retention). | |
| Mode of Administration | Online survey | |
| Notes | 45‐60 minutes to complete. Reminder messages were sent at 5 days and at 10 days for those who did not complete the survey. At 14 days, participants who had not yet opened the survey link were emailed to ensure that the survey emails were not sent to a spam folder. If there was no response to the individual email, project staff telephoned the non‐respondents. At 21 days, project staff attempted to email or call the non‐respondents. The publication also reports results of a second RCT with the same participants and is thus not independent of the first study; it has thus not been included in the 2023 review update. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated random number using Microsoft Excel |
| Allocation concealment? | Yes | Random allocation: computer‐generated random number using Microsoft Excel |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders (44 days) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Lavelle 2008.
| Study characteristics | ||
| Methods | Random allocation: computer generated using SPSS | |
| Data | Patients attending breast clinics in Greater Manchester between 1/10/2002 ‐ 31/7/2003 | |
| Comparisons | 1. First‐class stamp on addressed reply envelope 2. Pre‐paid addressed reply envelope |
|
| Outcomes | Response period not specified | |
| Topic | Health: functional health status ‐ ELPHS ADL; generic health status ‐ SF‐12; health‐related quality of life ‐ EORTC QLQ‐C30 | |
| Mode of Administration | Postal | |
| Notes | 6 pages, package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Leece 2004.
| Study characteristics | ||
| Methods | Quasi‐random allocation: alternately assigned members to receive a postal or an Internet questionnaire. | |
| Data | 442 surgeon‐members of the Orthopaedic Trauma Association | |
| Comparisons | Postal vs. electronic | |
| Outcomes | Response after 22 weeks (2 reminders) | |
| Topic | Health (preferences and practice patterns of orthopaedic traumatologists in the operative treatment for femoral neck fractures) | |
| Mode of Administration | Postal and electronic | |
| Notes | 8 pages. The Web questionnaire was 6 pages and took approximately 5 minutes to complete, and had 38 questions. Advanced notification by post (mail group) or email (Internet group) 2 to 5 days prior to receiving the survey; then a mailed copy of the survey, or an email with a link to the Internet survey; then another mailed copy or email with link to the survey at 6 weeks; then a further copy or link at 12 weeks; and finally a copy of the survey sent by mail only to all non‐respondents in both groups (22 weeks for the mail group and 19 weeks for the Internet group) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Quasi‐random allocation: alternately assigned members to receive a postal or an Internet questionnaire |
| Allocation concealment? | No | Quasi‐random allocation: alternately assigned members to receive a postal or an Internet questionnaire |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 22 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Leece 2006a.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Surgeon members of the Orthopaedic Trauma Association | |
| Comparisons | 1. Standard cover letter 2. Test cover letter (more personal) |
|
| Outcomes | Response period 6 weeks | |
| Topic | Health: preferences in the treatment of femoral neck fractures | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Leece 2006b.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Surgeon members of the Orthopaedic Trauma Association | |
| Comparisons | 1. Standard cover letter 2. Test cover letter (more personal) |
|
| Outcomes | Response period 6 weeks | |
| Topic | Health: preferences in the treatment of femoral neck fractures | |
| Mode of Administration | Electronic: email | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Leigh Brown 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Patients who had already responded a questionnaire about hospital attendance | |
| Comparisons | 1. Aware of monthly prize draw offering £25 gift voucher 2. Unaware of monthly prize draw offering £25 gift voucher | |
| Outcomes | Response period not specified | |
| Topic | Health: health status, satisfaction with orthopaedic referral | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Leung 2002.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Physicians randomly selected from the full and limited registration lists of the Hong Kong Medical Council | |
| Comparisons | 1. No incentive 2. $10 cash 3. $20 cash 4. $40 cash 5. Entry into $1000 lottery 6. Entry into $2000 lottery 7. Entry into $4000 lottery | |
| Outcomes | Response within 30 days | |
| Topic | Health: nature of practice, remuneration, clinical and administrative task | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Leung 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Physicians randomly selected from the full and limited registration lists of the Hong Kong Medical Council | |
| Comparisons | 1. Prepayment HK$20 2. Post‐payment HK$20 |
|
| Outcomes | Response within 60 days | |
| Topic | Health: computerisation of clinical and administrative tasks | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Final response after 2 postal reminders and one telephone call reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Levy 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 800 dermatologists, US | |
| Comparisons | Personalised handwritten note on letter vs. no note Non‐monetary incentive (mint sweets) vs. no incentive Personalised reminder postcard vs. pre‐printed reminder postcard | |
| Outcomes | Final response after 6 weeks (2 reminders) | |
| Topic | Health (physician attitudes and beliefs surrounding dysplastic nevi) | |
| Mode of Administration | Postal | |
| Notes | 4 pages. Letter and questionnaire initially sent. Reminder postcard sent 1 week later, and a second mailing of the questionnaire to those who had not yet responded approximately 6 weeks after the initial mailing. The initial cover letter included the recipient's name and address and a brief summary of the study, and it concluded with preprinted signatures of the investigators. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Lewis 2017.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | 611 participants who were due to be sent a 4‐month follow‐up questionnaire for the CASPER and CASPER SHARD trials | |
| Comparisons | Post‐it note with printed request to respond vs. no Post‐it note | |
| Outcomes | Response after 8 weeks (2 reminders: one postal, one telephone) | |
| Topic | Health (healthcare‐related study with older people suffering from depression) | |
| Mode of Administration | Postal | |
| Notes | PHQ‐9 (9 questions on 1 page). After 4 weeks, non‐respondents were sent a reminder letter and questionnaire; if no response, a follow‐up phone call was given after a further 4 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 8 weeks (2 reminders: one postal, one telephone) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Lewis 2017a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in the 2015 Federal Employee Viewpoint Survey, US | |
| Comparisons | Initial email invitation and all reminders sent on Tuesday morning ('traditional') vs. emails sent cycling around Tuesday p.m., Wednesday a.m., Wednesday p.m., Thursday a.m., Thursday p.m. ('rotating') vs. emails sent according to multinomial logistic regression model prediction of optimal day ('dynamic adaptive') | |
| Outcomes | Response after 6 reminder emails | |
| Topic | Non‐health (range of employee perceptions, attitudes, and behaviours, serving as a valuable tool for human resource managers to determine which aspects of an organisation are working well and which may require intervention) | |
| Mode of Administration | Web survey | |
| Notes | 88‐item survey (20 demographic questions and 68 items that were grouped into eleven topic headings including personal work experience, leadership, employee satisfaction, work‐life, employment demographics). The data collection protocol begins by sending all sampled individuals an initial invitation to participate. Thereafter, non‐respondents are sent weekly reminder emails. These notifications are typically sent on Tuesday mornings. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Linsky 1965.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Nurses | |
| Comparisons | 1. Characteristics of cover letter: personalised (P); social utility appeal (SU); explanation of place and importance of respondent in study (RP); an appeal to help researchers of study (HR) 2. Not P; SU; RP; HR 3. P; Not SU; RP; HR 4. Not P; Not SU; RP; HR 5. P; SU; Not RP; HR 6. Not P; SU; Not RP; HR 7. P; SU; RP; Not HR 8. Not P; SU; RP; Not HR 9. P; Not SU; Not RP; HR 10. Not P; Not SU; Not RP; HR 11. P; Not SU; RP; Not HR 12. Not P; Not SU; RP; Not HR 13. P; SU; Not RP; Not HR 14. Not P; SU, Not RP; Not HR 15. P; Not SU; Not RP; Not HR 16. Not P; Not SU; Not RP; Not HR | |
| Outcomes | Response within 3 weeks | |
| Topic | Health: not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Little 1990.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Respondents to a national magazine clip ad promotion | |
| Comparisons | 1. 25 cents 2. Pan‐scrapper 3. Control |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceptions of the product and follow‐up service to competing products | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Loban 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in the second wave of a cohort study on health and well‐being amongst the population of Yorkshire, UK | |
| Comparisons | Electronic with postal follow‐up vs. postal with electronic follow‐up | |
| Outcomes | Response after one month (one reminder) | |
| Topic | Health (general health and well‐being) | |
| Mode of Administration | Postal and electronic | |
| Notes | 8‐page questionnaire The electronic completion arm was contacted by email with a URL to complete the questionnaire online. If no responses were received within a month, a questionnaire containing the same questions was sent by post; the control group initially received an identical questionnaire by post; if after a month no response had been obtained, a reminder was sent via email with a URL to complete the questionnaire online. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after one month (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
London 1990a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Electronics design engineers | |
| Comparisons | 1. Standard cover letter 2. As (1) but also told would be entered into a prize draw for 3 calculators if responded 3. As (2) but also told that all respondents would receive a special gift from the sponsor | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: potential customers needs, firm usage, sources of transformers and inductors | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
London 1990b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Electronics design engineers | |
| Comparisons | 1. No incentive 2. $1 incentive | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: potential customers needs, firm usage, sources of transformers and inductors | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Lorenzi 1988.
| Study characteristics | ||
| Methods | Random allocation: methods not specified | |
| Data | Business executives, state legislators, and director of chambers of commerce from the Midwestern United States | |
| Comparisons | 1. Unconditional $1 payoff 2. Conditional $2 payoff 3. Lottery to win $50, $30, or $20 4. No incentives |
|
| Outcomes | Response within 14 days | |
| Topic | Non‐health: finance ‐ financial investment scenario, behavioural self‐description measure of propensity for risk in personal and business investments | |
| Mode of Administration | Postal | |
| Notes | Mean age: 49.7 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Lund 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Norwegian women aged 34‐49 years | |
| Comparisons | 1. Questionnaire entitled 'Women Lifestyle & Health'; 4 pages 2. Questionnaire entitled "Women & Cancer"; 2 pages 3. Questionnaire entitled "Women & Cancer"; 4 pages 4. Questionnaire entitled "Women & Cancer"; 6 pages 5. Questionnaire entitled "Oral Contraceptives & Cancer"; 2 pages | |
| Outcomes | Response period not specified | |
| Topic | Health: diet, sunbathing habits, occupational exposure, pharmaceutical drugs | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Lusinchi 2007.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 601 electronics engineers and engineering managers, US | |
| Comparisons | Pre‐notification email vs. none Scrollable web page vs. multiple web pages | |
| Outcomes | Final response after 3 weeks (3 reminders) | |
| Topic | Non‐health (integrated circuit design) | |
| Mode of Administration | Web survey | |
| Notes | 26 questions. Emails sent, followed by three reminders: the first was sent two days after the beginning of the field period; the second was sent four days after the first; and the third was sent a week after the second reminder. The scroll‐type version had 2 pages: the home page and the questionnaire page; the multiple‐page version consisted of 30 pages, including the home page and the contact information page. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
MacLennan 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients with type 2 diabetes participating in the RECORD trial who had not responded to the one‐year follow‐up questionnaire | |
| Comparisons | Pre‐notification telephone call vs. no pre‐notification | |
| Outcomes | Response within 21 days | |
| Topic | Health (diabetes) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response within 21 days reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Maheux 1989a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians who had failed to respond to a previous questionnaire (Quebec, UK) | |
| Comparisons | 1. Follow‐up letter with handwritten postscript 2. Follow‐up letter with no postscript | |
| Outcomes | Response within 6 months | |
| Topic | Health: support for patient care issues | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Maheux 1989b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians who had failed to respond to 2 mailings of a questionnaire (Quebec, UK) | |
| Comparisons | 1. Personalised mailout package 2. Non‐personalised mailout package | |
| Outcomes | Response within 6 months | |
| Topic | Health: support for patient care issues | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mallen 2008.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Patients aged 50 and over from the Central Cheshire general practices who consulted their GP for non‐inflammatory musculoskeletal pain between September 2006–April 2007 | |
| Comparisons | 1. Small font size ‐ Arial 12 2. Large font size ‐ Arial 16 3. Thin paper ‐ 80 g 4. Thick paper ‐ 100 g |
|
| Outcomes | Response period not specified | |
| Topic | Health: prognosis of older people with joint pain in general practice | |
| Mode of Administration | Postal | |
| Notes | 7 questions. Questionnaire booklets A4‐sized, mailed first class in white A4‐sized envelope. Participants received identical information sheets and a prepaid envelope to return their questionnaire. Those not responding to the initial questionnaire were sent a reminder postcard at 2 weeks and a further copy of the same questionnaire at 4 weeks. 2 x 2 factorial design based on two different font sizes (Arial size 12 [small font] vs. Arial size 16 [largefont]), and two paper thicknesses (80 g [thin paper] vs.100 g [thick paper]) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Man 2011.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants in an RCT investigating the role of yoga for the treatment of lower back pain | |
| Comparisons | Electronic prompt (email or SMS) vs. no prompt | |
| Outcomes | Response after 42 days (2 reminders) | |
| Topic | Health (yoga for the treatment of lower back pain) | |
| Mode of Administration | Postal | |
| Notes | 20 pages. Questionnaire with instructions to complete and return using the SAE. All participants also received £5 as an incentive to complete the questionnaire. Non‐responders were sent reminder letters after 2 and 4 weeks, up to a total trial follow‐up period of 42 days. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 42 days (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mann 2005.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Registered voters in Maryland, New York, and Pennsylvania | |
| Comparisons | 1. Advance letter 2. No advance letter |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: voting behaviour | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mann 2008.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Parents of 292 young adults eligible for the Hutchinson Smoking Prevention Project, Washington, US | |
| Comparisons | Smaller unconditional monetary incentive ($1) vs. larger unconditional monetary incentive ($2) vs. no incentive | |
| Outcomes | First and final responses (after reminder mailings and phone calls) | |
| Topic | Health (smoking) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Used a mixed‐mode procedure involving multiple mailings and telephone follow‐up of non‐responders | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First and final responses (after reminder mailings and phone calls) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Marcus 2007.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | Owners of personal websites | |
| Comparisons | 1. High topic salience ‐ motives and personality of personal website owners 2. Low topic salience ‐ psychological aspects of Internet usage 3. Long survey ‐ 359 items, 30‐60 minutes for completion 4. Short survey ‐ 91 items, 10‐20 minutes for completion 5. Lottery to win 2 Internet book store vouchers of 25 euro each 6. No lottery 7. Personalised feedback of the results (individual profile of the results) 8. Generalised (study results) or no feedback |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: Internet competence | |
| Mode of Administration | Electronic: Web survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Marrett 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents with histologically confirmed renal cell carcinoma (Ontario, US) | |
| Comparisons | 1. Lottery ticket incentive 2. No incentive | |
| Outcomes | — | |
| Topic | Health: history of urinary tract infection, use of analgesic and diuretic medication, demographics | |
| Mode of Administration | Postal | |
| Notes | Allocation was not concealed from the person sending out the letters; age: 25‐69 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Marsh 1999.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Parents of children aged 3‐12 months from general practices involved in a cluster‐randomised trial in Nottingham, UK who had responded to a previous questionnaire | |
| Comparisons | 1. Promise of a £2 voucher for a local children's store on return of the questionnaire (postal) 2. No incentive (postal) | |
| Outcomes | Response period not specified | |
| Topic | Health: near miss and minor injuries | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Martin 1970.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a telephone directory (Washington, US) | |
| Comparisons | 1. Personalised letter (PL); appeal to importance (AI); commemorative stamp (CS); easy questionnaire (EQ) first 2. PL; AI; CS; EQ not first 3. PL; AI; business reply frank (BRF) instead of CS 4. PL; AI; BRF; EQ not first 5. PL; no AI; CS; EQ first 6. PL; no AI; CS; EQ not first 7. PL; no AI; BRF; EQ first 8. PL; no AI; BRF; EQ not first 9. Letter not personalised (NPL); AI; CS; EQ first 10. NPL; AI; CS; EQ not first 11. NPL; AI; BRF; EQ first 12. NPL; AI; BRF; EQ not first 13. NPL; no AI; CS; EQ first 14. NPL; no AI; CS; EQ not first 15. NPL; no AI; BRF; EQ first 16. NPL; no AI; BRF; EQ not first | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: public and judicial attitudes toward various aspects of the legal machinery | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Martin 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | University students | |
| Comparisons | 1. Pre‐notification (PN); Follow up (FU); Personalised (PS); Stamped reply envelope (SRE) 2. PN; no FU; PS; SRE 3. PN; FU; no PS; SRE 4. PN; no FU; no PS; SRE 5. PN; FU; PS; business reply envelope (BRE) 6. PN; no FU; PS; BRE 7. PN; FU; no PS; BRE 8. PN; no FU; no PS; BRE 9. No PN; FU; PS; SRE 10. No PN; no FU; PS; SRE 11. No PN; FU; no PS; SRE 12. No PN; no FU; no PS; SRE 13. No PN; FU; PS; BRE 14. No PN; no FU; PS; BRE 15. No PN; FU; no PS; BRE 16. No PN; no FU; no PS; BRE | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: information on the perceived attributes of the university | |
| Mode of Administration | Postal | |
| Notes | Mean age: 30 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Martin 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Participants of a large international amateur bowling tournament | |
| Comparisons | 1. High‐interest questionnaire 2. Low‐interest questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: interpersonal relationships with other customers in service environment | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Martinson 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adolescents aged 14‐17 years in the Minneapolis/St Paul metropolitan area | |
| Comparisons | 1. $2 included with questionnaire 2. $15 promised on completion and return of questionnaire 3. Promise of entry into 10 drawings for 10 $200 cash prizes on completion and return of questionnaire 4. No incentive | |
| Outcomes | — | |
| Topic | Health: attitudes towards smoking, behavioural health‐related items | |
| Mode of Administration | Postal | |
| Notes | Reminder and second questionnaire sent to non‐responders 1 week and 3 weeks after initial mailing, respectively; age: 14‐17 years; equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mason 1961.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Teachers | |
| Comparisons | 1. Long form; name and address on form 2. Long form; code number on form 3. Short form; name and address on form 4. Short form; code number on form | |
| Outcomes | — | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Matteson 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of a national organisation | |
| Comparisons | 1. Semi‐personalised letter; white questionnaire 2. Semi‐personalised letter; pink questionnaire 3. Form letter; white questionnaire 4. Form letter; pink questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: significant contribution of literature in their field | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mauz 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Children and adolescents registered in the local resident registries of 20 municipalities in 5 federal states of Germany, participating in the third wave of the 'German Health Interview and Examination Survey for Children and Adolescents' | |
| Comparisons | Choice (electronic/postal) vs. only postal response; postal vs. electronic; pre‐selected choice vs. choice (electronic/postal) | |
| Outcomes | Response after 1 reminder | |
| Topic | Health (physical and mental health as well as parent‐ or self‐reported information regarding the subjective health status, health behaviour, health care utilisation, social and migration status, living conditions, and environmental determinants of health). | |
| Mode of Administration | Postal/electronic | |
| Notes | Sociodemographic characteristics and a broad range of health indicators for children and adolescents were compared by survey design. Individuals mailed invitations. They were sent a cover letter with the invitation to participate, information about the study and data privacy, and an informed consent form. Depending on the allocated mode, the invitation comprised a username and password for participation through the Web option, along with a paper questionnaire for those allocated to the concurrent mixed‐mode design, only a paper questionnaire in the single‐mode design, or only the access data for the online questionnaire in the sequential mixed‐mode design. The SAQ‐Web questionnaire was only optimised for desktop computers. A reminder was sent by mail to respondents who had not replied within 3 weeks of the initial invitation. Participants who did not respond to the reminder were telephoned up to 5 times 4 weeks after the initial invitation. As an additional motivation for prospective participants, each parent and adolescent who had completed a questionnaire received a shopping voucher to the value of EU 10. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Maxwell 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Population‐based sample of colorectal cancer cases and their first‐degree relatives | |
| Comparisons | Monetary incentive vs. no incentive; non‐monetary incentive vs. no incentive; certified/special delivery vs. regular outward mailing | |
| Outcomes | Final response after telephone reminders | |
| Topic | Health (colorectal cancer screening) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Initial recruitment of both cases and relatives was conducted via mail, followed by up to 10 telephone attempts if no response was received within 10 days. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | Although participants were unaware of incentive structures for other invitees, interviewers who did the telephone follow‐up attempts were aware of the incentive status of all subjects. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Final response after telephone reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McCaffery 2019.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Potential elderly participants in the OTIS trial of falls prevention, UK | |
| Comparisons | Handwritten name vs. printed name | |
| Outcomes | First response | |
| Topic | Health (screening questionnaire for the OTIS trial of falls prevention) | |
| Mode of Administration | Postal | |
| Notes | 2 pages, 8 questions. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McCambridge 2011.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants in the DYD‐RCT (Down Your Drink), a large trial of online intervention to help hazardous drinkers reduce their alcohol consumption | |
| Comparisons | Longer questionnaire vs. shorter; more salience/relevant (to alcohol problems) vs. less (mental health) | |
| Outcomes | Response within 40 days (after 3 reminders) | |
| Topic | Health (alcohol consumption) | |
| Mode of Administration | Electronic | |
| Notes | 23 questions (longer); 10 questions (shorter). Participants were sent email requests for follow‐up data after 1 and 3 months (study 1) and after 3 and 12 months (study 2). Up to three reminders were sent at 7‐day intervals to non‐responders. Study 1, 1‐month time point, selected for inclusion in review Hypotheses: (1) longer questionnaires (23 or 34 versus 10 items included in secondary outcome measures) will produce lower rates of follow‐up and (2) more relevant questionnaires (defined as assessing alcohol problems rather than mental health) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Blinding of personnel not described. Participants answered two questions on confidence and intentions before arriving at a final questionnaire prior to being told their parent trial group allocation. Without their knowledge, participants had been randomly allocated to one of four different questionnaires (described below) to be completed as this final questionnaire. Participants were thus blinded to the conduct of this study. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response within 40 days (after 3 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McColl 2003a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adults with angina from 62 family practices in Northeast England | |
| Comparisons | 1. Version 1: Condition‐specific questionnaires (Seattle Angina Questionnaire) first, followed by generic questionnaires (SF‐36 & EQ‐5D) 2. Version 2: Generic questionnaires first, followed by condition‐specific questionnaires |
|
| Outcomes | Response period not specified | |
| Topic | Health: patient‐based outcome measures | |
| Mode of Administration | Postal | |
| Notes | Reminder and second questionnaire sent to non‐responders 3 weeks and 6 weeks after initial mailing, respectively; mean age: 69.1 years; mainly male | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McColl 2003b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adults with asthma from 62 family practices in Northeast England | |
| Comparisons | 1. Version 1: Condition‐specific questionnaires (Newcastle Asthma Symptoms Questionnaire & Asthma Quality of Life Questionnaire) first, followed by generic questionnaires (SF‐36 & EQ‐5D) 2. Version 2: Generic questionnaires first, followed by condition‐specific questionnaires |
|
| Outcomes | Response period not specified | |
| Topic | Health: patient‐based outcome measures | |
| Mode of Administration | Postal | |
| Notes | Reminder and second questionnaire sent to non‐responders 3 weeks and 6 weeks after initial mailing, respectively; mean age: 48.6 years; mainly female | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McConochie 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Males aged 18‐34 | |
| Comparisons | 1. 50 cents incentive 2. $2 incentive 3. $5 incentive | |
| Outcomes | Response within 1 week | |
| Topic | Non‐health: measurement of radio listening | |
| Mode of Administration | Postal | |
| Notes | Age: 18‐34 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McCormack 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 520 rural women followed by the South Dakota State University Study Call Center regarding eligibility for the National Children's Study | |
| Comparisons | Unconditional monetary incentive ($2) vs. no incentive | |
| Outcomes | Response within 75 days | |
| Topic | Health (pregnancy status and probability of becoming pregnant) | |
| Mode of Administration | Postal | |
| Notes | One page. Questionnaire sent with a business‐reply paid envelope | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response within 75 days reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McCoy 2007.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Institute of Public Relations (IPR) members in Northern Ireland | |
| Comparisons | 1. Handwritten address 2. Computer‐printed address 3. Brown envelope 4. White envelope |
|
| Outcomes | Deadline for return provided | |
| Topic | Non‐health: practices and attitudes towards public relations evaluation | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Random allocation: using alternation |
| Allocation concealment? | No | Random allocation: using alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Final response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McDaniel 1980.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Major‐appliance purchasers | |
| Comparisons | 1. 25‐cent incentive 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: product warranty questionnaire | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McDaniel 1981.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Major‐appliance purchasers in Midwestern US | |
| Comparisons | 1. Anonymous (no name requested and no name given) 2. Non‐anonymous (name requested and given at the beginning of questionnaire) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: major appliance warranties and warranty performance | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McGonagle 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2473 non‐respondents in the U.S. Panel Study of Income Dynamics | |
| Comparisons | Larger monetary incentive (US $10) vs. smaller monetary incentive (US $5) vs. no incentive | |
| Outcomes | First response | |
| Topic | Non‐health (childhood experiences) | |
| Mode of Administration | Web or choice | |
| Notes | 20 minutes (292 items) For both web and choice groups, the study invitation included the web address of the survey and provided login credentials that were unique and randomly generated. The invitation letter sent to the choice group also stated that the survey could be completed on a paper questionnaire that would be mailed to their address after two weeks. To encourage the use of the web to complete the survey, no mention of a paper questionnaire was made in the initial invitation letter sent to the web group. In the incentive treatment conditions, a US bill in the amount of US $5 or US $10 was paper‐clipped to the top of the paper questionnaire to ensure visibility. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
McKee 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of a national non‐profit professional organisation | |
| Comparisons | 1. Coded
2. Not coded In coded group, only non‐respondents received follow‐up. In non‐coded group, all received follow‐up. |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: programme of the organisation | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McKenzie‐McHarg 2005.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Members and fellows of the Royal College of Obstetricians and Gynaecologists in the UK | |
| Comparisons | 1. Handwritten signature in the cover letter 2. Scanned and printed signature in the cover letter |
|
| Outcomes | Response period not specified | |
| Topic | Health: surgical techniques used in caesarean section operation in the UK | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McKillip 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Underclass men from a large rural Midwestern university (US) | |
| Comparisons | 1. Utility cover letter appeal 2. Value expression appeal 3. Knowledge appeal | |
| Outcomes | Response period not specified | |
| Topic | Health: evaluation activities for an alcohol education project | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McLaren 2000a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 700 Victorian general practitioners selected from a database held by Australasian Medical Publishing Company | |
| Comparisons | 1. Telephone pre‐notification 2. Postcard pre‐notification | |
| Outcomes | Response within 8 weeks | |
| Topic | Health: management of early pregnancy, bleeding and miscarriage, referral, diagnostic methods | |
| Mode of Administration | Postal | |
| Notes | Equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McLaren 2000b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 700 Victorian general practitioners selected from a database held by Australasian Medical Publishing Company | |
| Comparisons | 1. Promise of entry into a prize draw for a holiday on response 2. No incentive | |
| Outcomes | Response within 8 weeks | |
| Topic | Health: management of early pregnancy, bleeding and miscarriage, referral, diagnostic methods | |
| Mode of Administration | Postal | |
| Notes | Equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
McLean 2014.
| Study characteristics | ||
| Methods | Random allocation: random number generator in Microsoft Excel | |
| Data | 3010 adults from the state of Victoria, Australia, randomly selected from 11 metropolitan and 6 regional electorates of the Australian Electoral Roll | |
| Comparisons | Pre‐notification postcard vs. no pre‐notification postcard Envelope teaser vs. no envelope teaser | |
| Outcomes | First response and final response after one month (1 reminder) | |
| Topic | Health (bulimia nervosa) | |
| Mode of Administration | Postal | |
| Notes | 260 items. Questionnaires were sent with a personalised letter of invitation that fully explained the procedures of the study. Participants were offered a $10 shopping voucher, contingent on questionnaire return. Reminder questionnaires were mailed to non‐responders 1 month after the original questionnaire had been posted. Pre‐notification postcards were mailed 1 week before the initial mailing of the questionnaire. The envelope teaser was placed on the original and reminder envelopes. The 'teaser' sticker contained the text "You can share valuable information to help people with eating disorders". |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator in Microsoft Excel |
| Allocation concealment? | Yes | Random allocation: random number generator in Microsoft Excel |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response and final response after one month (1 reminder) reported in full |
| Other sources of bias | No | No grounds for concern about other sources of bias from reading the study report |
Meadows 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 600 diabetes patients aged 18 years or over selected from the patient register of a hospital outpatient diabetes centre in North England | |
| Comparisons | 1. High‐frequency response alternatives; horizontal orientation of response options 2. Medium‐frequency response alternatives; horizontal orientation of response options 3. High‐frequency response alternatives; vertical orientation of response options | |
| Outcomes | Response period not specified | |
| Topic | Health: diabetes health profile | |
| Mode of Administration | Postal | |
| Notes | The high‐frequency response alternatives are: most days, once a week, once a month, less often, never
The medium‐frequency response alternatives are: once a week or more often, once a month, about every few months, less often, never Mean age: 52.2 years |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Meuleman 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Ghanian university students | |
| Comparisons | Unconditional non‐monetary incentives (EUR 1.20, 2.40 or 4.80 telephone credits) vs. conditional non‐monetary | |
| Outcomes | Students who started the survey and students who completed the survey | |
| Topic | Non‐health (the extent to which Ghana‚ National Service Scheme programme contributes to improving intergroup relations and fostering stronger national identities amongst its participants). | |
| Mode of Administration | Electronic (web survey) | |
| Notes | Questionnaire not described 5570 students who filled out the background questionnaire were invited by email and text message to participate in an online survey. For students receiving an unconditional incentive, the mobile phone top‐up‚ together with a text message indicating that the top‐up was meant as a token of gratitude for their participation in the survey‚ was sent to the respondents' phones just before they received the survey invitation by email. Respondents on a conditional incentive condition received a text message saying that they would receive a top‐up upon completing the survey. Numbers of students who started the survey and the numbers of students who completed the survey by incentive condition provided by the first author. The Ghanaian social context offered an interesting opportunity: quasi‐cash incentives as mobile phone credit, so‐called top‐up. In Ghana, top‐ups are easily transmittable and used almost universally as a mode of economic exchange. Top‐ups, thus, are a functional equivalent of cash in Ghana. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Two hundred and fifty five students did not provide a valid email address, and 1130 invitation emails bounced, leaving us with a sample of 4440 students. |
| Selective reporting | Yes | Numbers of students who started the survey and the numbers of students who completed the survey by incentive condition provided by the author |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Millar 2011a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Highly Internet‐literate population with full Internet access. 2800 undergraduate students at the main campus of Washington State University | |
| Comparisons | Choice (mail or Web) vs. mail only vs. Web only | |
| Outcomes | Final response after one reminder | |
| Topic | Non‐Health (students' opinions about a variety of issues related to their educational experiences at university) | |
| Mode of Administration | Electronic/postal | |
| Notes | Questionnaire contained 36 questions All groups were contacted initially via postal letters and given a $2 bill as an incentive. The choice group students received a paper questionnaire (with an SAE) as well as the Website and individualised access codes for responding online. The mail group students were given only the paper questionnaire with an SAE. The Web only groups were given only the website and individualised access codes, and no paper questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Millar 2011b.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Highly Internet‐literate population with full Internet access. A random sample of 4300 students of Washington State University | |
| Comparisons | Unconditional monetary incentive ($2) vs. no incentive | |
| Outcomes | Final response after one reminder | |
| Topic | Non‐health (how students have been affected by the recent economic downturn and the university's resulting budget cuts) | |
| Mode of Administration | Electronic/postal | |
| Notes | Questionnaire contained 33 questions. All groups were contacted initially via postal letters and given a $2 bill as an incentive. The choice group students received a paper questionnaire (with an SAE) as well as the Website and individualised access codes for responding online. The mail group students were given only the paper questionnaire with an SAE. The Web only groups were given only the website and individualised access codes, and no paper questionnaire. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Millar 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Adults with colorectal, breast, prostate, ovarian, and multiple myeloma cancers, reported in the Utah Cancer Registry, US | |
| Comparisons | Postal vs. Web Brochure describing the cancer registry vs. no brochure | |
| Outcomes | First and final (after 3 reminders) responses | |
| Topic | Health (current health, cancer recurrence, and willingness to participate in various kinds of cancer research) | |
| Mode of Administration | Postal vs. Web | |
| Notes | 35 items; formatted a paper questionnaire to visually resemble the web‐based instrument. On the paper questionnaire, each item was enclosed in a box to resemble the page‐by‐page display of the web instrument. The same imagery was used on the paper questionnaire cover and the welcome screen of the web instrument. For both survey modes, the initial mode of contact was postal mail, as email addresses are not routinely obtained in cancer registry reports. Potential participants received up to four mailings (pre‐notification letter with or without brochure, invitation packet with either questionnaire and stamped return envelope or web survey instructions, thank‐you/reminder letter, and a replacement packet). All mailings utilised official University of Utah letterhead and envelopes, as well as postage stamps for outgoing and return‐envelope postage. For the paper survey arm, each of these contacts requested response by paper questionnaire, and the web response option was not offered. For the web arm, all of these contacts only mentioned response via the web‐based questionnaire, and unlike the standard web‐push approach, a paper response option was never offered. We formatted a paper questionnaire to visually resemble the web‐based instrument as much as possible to reduce mode effects. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Miller 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Full‐time professors at doctorate granting or comprehensive universities | |
| Comparisons | 1. Incentive (decaffeinated coffee bag)
2. No incentive
3. Cover letter appeal: 'Your input into this matter is very important in determining what faculty consider scholarship to be'.
4. Cover letter appeal: 'It is important to ascertain what faculty consider scholarship to be, in order to develop models of scholarship and further knowledge'. Follow‐up at 3 and 6 weeks after initial mailing |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: faculty attitudes about the personal importance of scholarly activities, institutional importance of scholarly activities, attitudes about faculty workload | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mills 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Owners of agricultural or residential property, Michigan, US | |
| Comparisons | Single cash note ($2) vs. multiple notes (2 x $1) | |
| Outcomes | Response after 2 weeks (one reminder) | |
| Topic | Non‐health (effects of wind energy on rural landowners) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Personalised pre‐notification letter on colour letterhead in a stamped (rather than metered mail) envelope. One week later, all were mailed a questionnaire and a personalised survey invitation letter with $2 prepaid incentive (affixed with handwritten thank‐you sticker) along with an SAE. A week later, all were sent a postcard reminder. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 2 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mitchell 2011.
| Study characteristics | ||
| Methods | Quasi random allocation: alternation | |
| Data | Women aged 70‐85 years recruited from 100 GP practices into the SCOOP (SCreening Of Older women for fracture Prevention) trial | |
| Comparisons | Brown envelope vs. white envelope | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (self‐reported fractures over last 12 months) | |
| Mode of Administration | Postal | |
| Notes | Contained three health screening questions; York‐modified SF‐12, EQ‐5D and the State‐Trait Anxiety Inventory. The invitation was either in a brown or white envelope and contained a matching pre‐paid reply envelope. A study questionnaire was sent in brown or white envelopes 1 week after consenting to participate. A reminder was sent after 14 days. Telephone reminder 30 days after first mailing | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Random allocation: alternately allocated by alphabetical surname. This systematic method of allocation is as effective at producing equivalent groups as true randomisation if there is no relationship between sequence and prognostic variables and if the person sending out the envelopes is not aware of the prognostic characteristics of the participants. In this instance, both of these criteria were fulfilled. |
| Allocation concealment? | No | Quasi‐random allocation: alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mitchell 2012.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants of the Medical Research Council's SCOOP trial of screening older women (aged 70‐84) for fracture risk from Norwich and York centres (n = 2562), UK | |
| Comparisons | Pre‐notification newsletter vs. none | |
| Outcomes | Response after one reminder. | |
| Topic | Health (fracture incidence, quality of life and resource use) | |
| Mode of Administration | Postal | |
| Notes | EQ‐5D (2 pages), SF‐12 (3 pages), and State‐Trait Anxiety Index (2 pages). The newsletter took the form of an A5 single sheet, which was folded into a booklet. The newsletter gave the participants an update on the trials' progress, and reminded them about the importance of returning their questionnaires. On the back of the newsletter, there was a brief description, and photograph, of the local study team, with a reminder of contact details for any queries. The newsletter was sent out to the intervention participants approximately 6 weeks before they were due to receive their 24‐month questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported. A number of individuals were excluded from the analysis: died before or within 1 month of mailing (n = 16, intervention; n = 9, control n = 7); participant followed up by telephone only (n = 1, control participant); or lost to follow‐up (n = 1, intervention participant).. |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mitchell 2021a.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants in the Knee Replacement Bandaging Study (KReBS) RCT, UK | |
| Comparisons | Personalised text message reminder vs. non‐personalised text message reminder | |
| Outcomes | Final response | |
| Topic | Health (patient‐reported outcomes in total knee replacement patients) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Package not described. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | Neither personnel nor participants were blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Five participants died or withdrew following randomisation. |
| Selective reporting | Yes | Completion and return rate outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mitchell 2021b.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Follow‐up of participants in a clinical trial of compression bandaging following knee arthroplasty | |
| Comparisons | Pen (branded with the York Trials Unit and University of York logos) vs. no pen | |
| Outcomes | First response | |
| Topic | Health (outcomes following knee arthroplasty) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Questionnaire package not described. The incentive pen was branded with the York Trials Unit and University of York logos. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | No | Neither participants nor personnel were blinded. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mizes 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians specialising in allergy randomly selected from all physicians listed under allergy or allergy/immunology in the telephone directory yellow pages of major metropolitan areas across the US | |
| Comparisons | 1. No incentive; answer postcard 2. $1 cheque; answer postcard 3. $5 cheque; answer postcard 4. $1 cheque; answer cheque 5. $5 cheque; answer cheque |
|
| Outcomes | Response period not specified | |
| Topic | Health: incidence, treatment, and the success of treatment of rhinitis medicamentosa | |
| Mode of Administration | Postal | |
| Notes | Method of allocation confirmed through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mockovak 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Random sample of 1000 purchasers of the print copy of the Bureau of Labor Statistics Occupational Outlook Handbook, selected from a list provided by the Government Printing Office, US | |
| Comparisons | Cover letter redesigned using the principles of Information Mapping (bold headings as questions, e.g., 'What is the purpose of this survey?' and 'How long will this take?') vs. conventional cover letter | |
| Outcomes | Response rate after one mailing | |
| Topic | Non‐health (opinion on discontinuation of publication of the print version of the Bureau of Labor Statistics‚ Occupational Outlook Handbook) | |
| Mode of Administration | Postal/electronic | |
| Notes | 6 items. Respondents were contacted via mail and given the option of either mailing back a simple, 6‐item paper questionnaire or completing a Web version of the form. There was no pre‐survey notification, one mailed contact attempt, and no follow‐up attempts. Also, no incentives were used. Respondents were asked to complete and return the survey within 30 days. Respondents accessed the Web survey by entering a simple URL in their Web browser. The Web survey did not require use of either a username or password. The content of the one‐page cover letter in each group was almost identical. The primary differences were the word labels, which were bolded, and the general formatting used by the Information Mapping version. No colour was used on either version. The primary appeal for co‐operation was an egoistic one, since discontinuation of the printed copy could potentially lead to negative impacts on the users of the print version of the Handbook. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Mond 2004.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | Australian Capital Territory residents | |
| Comparisons | 1. Short questionnaire (8 pages long) 2. Long questionnaire (14 pages long) |
|
| Outcomes | Response after 2 reminders (8 weeks) | |
| Topic | Health (psychological distress, disability, and quality of life) | |
| Mode of Administration | Postal | |
| Notes | 8 pages vs. 14 pages. A first reminder letter was sent to non‐respondents 8 weeks after initial mailout. Replacement questionnaires were posted to individuals who received the initial questionnaire by hand delivery. Amongst non‐respondents who received the initial questionnaire by post, half received a replacement questionnaire by post and the remaining half received a second copy of the questionnaire by hand delivery. Remaining non‐respondents received a second reminder letter (and replacement questionnaire) by post after a further 8 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 2 reminders (8 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Morgan 2017.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants in the host RCT of Cool Little Kids Online were Australian parents of children aged 3 to 6 years who were assessed as high on temperamental inhibition. | |
| Comparisons | Conditional non‐monetary incentive (lottery with 1 in 20 chance of winning $50) vs. no incentive | |
| Outcomes | Response after 4 reminders | |
| Topic | Health (Alabama Parenting Questionnaire) | |
| Mode of Administration | Electronic | |
| Notes | Alabama Parenting Questionnaire (42 questions). The average duration to complete the questionnaire was 40 min. Participants were sent an email invitation with a link to complete the final study assessment 24 weeks after they had enrolled in the parent study. Non‐responders were sent an email reminder after 1 week, and a second reminder after a further week had passed. Those who had still not responded were telephoned 1 week later as a friendly reminder and to check if they had received the emails (a voicemail was left if the participant could not be reached). A final telephone contact was made after a further week or two had elapsed (by SMS if the participant had been reached by phone previously). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 4 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Morris 2013.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Women participating in a survey on experiences of fertility problems | |
| Comparisons | Electronic (web) vs. postal vs. telephone vs. choice | |
| Outcomes | Response after 3 reminders | |
| Topic | Health (fertility problems) | |
| Mode of Administration | Mixed, plus choice of telephone | |
| Notes | 44 questions, more than 16 pages. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Allocation to intervention was conducted by an external mailout company. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Morrison 2003.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | Local residents | |
| Comparisons | 1. Study feedback information booklet 2. No information booklet |
|
| Outcomes | Response period not specified | |
| Topic | Health: sociodemographics, travel behaviour, risk perception, attitudes to the local area and health | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mortagy 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Persons listed in electoral registers (Southampton and New Forest, UK) | |
| Comparisons | 1. Offered lottery ticket
2. Not offered lottery ticket Reminder sent to non‐respondents after 4 weeks |
|
| Outcomes | ||
| Topic | Health: respiratory symptoms such as breathlessness, wheezing, cough, phlegm, hyper‐irritability of the bronchi; family illness; smoking habits; drug treatment | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Moses 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Consultants identified from the Royal College of Obstetricians and Gynaecologists (RCOG) database | |
| Comparisons | 1. Prize draw incentive to win a personal digital assistant 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: current practice for the laparoscopic diagnosis and treatment of women with pelvic pain due to endometriosis | |
| Mode of Administration | Postal | |
| Notes | Single page; 10 questions. One reminder was sent to non‐responders after 3 months. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computerised random number generation |
| Allocation concealment? | Yes | Random allocation: computerised random number generation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Moss 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of the National Council for Educational Measurement | |
| Comparisons | 1. Typed salutation; metered return envelope 2. Typed salutation; non‐metered return envelope 3. Handwritten salutation; metered return envelope 4. Handwritten salutation; non‐metered return envelope | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: respondents belief about the frequency and credibility of criticisms of standardised test | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mullen 1987.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Non‐federal office‐based members of the American Academy | |
| Comparisons | 1. Blue and white sticker incentive only
2. Withdrawal provision only
3. Incentive and withdrawal provision
4. No treatment Non‐respondents followed up 3 times |
|
| Outcomes | — | |
| Topic | Health: counselling adult patients about smoking, weight, exercise, and stress, interest in continuing education | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Mullner 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Community hospitals registered with the AHA (US) | |
| Comparisons | 1. Questionnaire in booklet form (QBF); most salient and relevant question first (SRF); cover letter personal in tone (CLP); results promised (RP) 2. QBF; SRF; CLP; no RP 3. QBF; SRF; cover letter impersonal in tone (CLI); RP 4. QBF; SRF; CLI; no RP 5. QBF; salient and relevant questions last (SRL); CLP; RP 6. QBF; SRL; CLP; no RP 7. QBF; SRL; CLI; RP 8. QBF; SRL; CLI; no RP 9. Questionnaire in 2‐sided form style (QF); SRF; CLP; RP 10. QF; SRF; CLP; no RP 11. QF; SRF; CLI; RP 12. QF; SRF; CLI; no RP 13. QF; SRL; CLP; RP 14. QF; SRL; CLP; no RP 15. QF; SRL; CLI; RP 16. QF; SRL; CLI; no RP | |
| Outcomes | Response period not specified | |
| Topic | Health: corporate planning, risk management programmes, expenditures for hospital supplies, admitting privileges of physicians, programmes of special services for the elderly | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Munoz 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | A sample of 95 participants (63 English‐speakers and 32 Spanish‐speakers) at high‐risk for depression recruited online to participate in a Healthy Mood study, US | |
| Comparisons | (140) Telephone and email reminder vs. email only reminder | |
| Outcomes | First response (at 1 month) | |
| Topic | Health (depression) | |
| Mode of Administration | Online | |
| Notes | All participants received monetary incentives in the form of online gift certificates to a popular online megastore. Participants received US $10 for completing each of the three follow‐up assessments (1, 3, and 6 months after consenting), and a US $20 bonus if all three follow‐ups were completed. Thus, a participant could earn up to US $50. At each follow‐up point, all participants received up to three emails in one week, inviting them to complete follow‐up by following an embedded link. Response at one month (time point one) included in review Participants were randomised to two conditions: (1) Call: Those randomised to the Call condition were phoned (up to 10 attempts were made to reach them) and asked to complete the surveys by phone if they did not fill out the survey online; (2) No Call. Those randomised to the No Call condition received no phone calls. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | All participants were informed, via the consent form, that they may receive phone calls if they did not complete follow‐up surveys online; thus the participants were blind to condition. Blinding of personnel was not reported. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Murawski 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Veterans aged 60‐65 | |
| Comparisons | 1. Duke questionnaire
2. SF‐36 questionnaire
3. SIP questionnaire Follow‐up sent 1 and 4 weeks |
|
| Outcomes | — | |
| Topic | Health: health‐related quality of life (HRQoL) | |
| Mode of Administration | Postal | |
| Notes | Age: 60‐65 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Murdoch 2014.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 324 male Gulf War I era veterans who had applied for disability benefits, US | |
| Comparisons | Identifying feature on return vs. none Higher monetary incentive ($20) vs. lower monetary incentive ($10) | |
| Outcomes | Response after 6 weeks (3 reminders) | |
| Topic | Health (combat, unwanted sexual attention, and other lifetime and military experiences) | |
| Mode of Administration | Postal | |
| Notes | 25‐page questionnaire. For all groups, the initial mailing included a cover letter (printed on Minneapolis VA Medical Center letter‐head and listed the study's funding agency), the cash incentive, and questionnaire. At two‐week intervals, non‐respondents were mailed postcard reminder, second mailing of the survey, and final mailing of the survey via overnight mail (Federal Express). | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | Neither participants nor personnel were blind to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 6 weeks (3 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Murphy 1991.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | International freight forwarders (US) | |
| Comparisons | 1. Pre‐notification postcard
2. No pre‐notification postcard Follow‐up sent after 3 weeks |
|
| Outcomes | Response within 62 days | |
| Topic | Non‐health: US industrial firm check | |
| Mode of Administration | Postal | |
| Notes | Age: 45‐48 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Murphy 2020.
| Study characteristics | ||
| Methods | Random allocation: randomisation log generated by a biostatistician | |
| Data | Physicians from the American Medical Association MasterFile from haematology or oncology specialties | |
| Comparisons | Mixed vs. electronic | |
| Outcomes | Response after 6 months (2 reminders) | |
| Topic | Health (characteristics of physicians' practices; referral and recruitment of patients to clinical trials; and barriers to trial accrual). | |
| Mode of Administration | Postal/electronic | |
| Notes | 5‐min survey. Mail‐based recruitment included a survey packet with: (1) cover letter describing the survey and inviting participation; (2) paper copy of the survey and postage‐paid return envelope; and (3) a reminder postcard with web link after 2 wks; (4) final reminder paper survey after 2 wks.
Email‐based recruitment included an email describing the survey and inviting participation, along with the web link. Reminder email after 1 wk; reminder postcard 2 weeks later Most physicians assigned to mail‐based recruitment actually completed the survey online via the link provided in the cover letter, and those in email‐based recruitment did not respond until they received a reminder postcard by mail. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: randomisation log generated by a biostatistician |
| Allocation concealment? | Yes | Random allocation: randomisation log generated by a biostatistician |
| Blinding of participants and personnel | Yes | Study investigators were blind to randomised assignment. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after each reminder, and after 6 months (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Myers 1969.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households listed in a street order telephone directory (Los Angeles, US) | |
| Comparisons | 1. Pre‐contact letter 2. Questionnaire only 3. Questionnaire, then follow‐up letter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: reaction of public to various promotion efforts by the bank to establish the image of the bank | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Myhre 2019a.
| Study characteristics | ||
| Methods | Quasi randomisation: alternation | |
| Data | Mothers of 6‐month‐olds; participants in a longitudinal study assessing dietary habits in infants, Norway | |
| Comparisons | Conditional non‐monetary incentive (50 EUR voucher) vs. conditional lottery (500 EUR and 1000 EUR) Handwritten name and address vs. printed label | |
| Outcomes | Response after 3 weeks (2 reminders) | |
| Topic | Health (national dietary survey amongst infants) | |
| Mode of Administration | Electronic (paper reminder questionnaire) | |
| Notes | 15 pages, containing a total of 28‐127 questions (depended on previous choices when answering the questionnaire), 20 mins completion time For all the invitees, the invitation contained information about the study and a link to a web‐based questionnaire. Telephone reminder to non‐responders after 1 wk and written reminder after 3 weeks, including paper questionnaire |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Quasi‐randomisation: alternation |
| Allocation concealment? | No | Quasi‐randomisation: alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Myhre 2019b.
| Study characteristics | ||
| Methods | Quasi randomisation: alternation | |
| Data | Mothers of 12‐month‐olds; participants in a longitudinal study assessing dietary habits in infants, Norway | |
| Comparisons | Email invitation vs. postal | |
| Outcomes | Response after 3 weeks (2 reminders) | |
| Topic | Health (national dietary survey amongst infants) | |
| Mode of Administration | Electronic (paper reminder questionnaire). | |
| Notes | 12 months
23 pages, 247‐275 questions, 40 mins completion time For all the invitees, the invitation contained information about the study and a link to a web‐based questionnaire. Telephone reminder to non‐responders after 1 wk and written reminder after 3 weeks, including paper questionnaire |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Quasi‐randomisation: alternation |
| Allocation concealment? | No | Quasi‐randomisation: alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Nagata 1995.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Male owners of telephones (Gitu City, Japan) | |
| Comparisons | 1. 1‐page; cigarette smoking and drinking
2. 2 pages; cigarette smoking and drinking; medical history
3. 2 pages; cigarette smoking and drinking; family history
4. 2 pages; cigarette smoking and drinking; family history; consanguineous marriage
5. 3 pages; cigarette smoking and drinking; medical history; family history; consanguineous marriage
6. 2 pages; cigarette smoking and drinking; medical history; family history; consanguineous marriage Follow‐up in group 1 only |
|
| Outcomes | Response period not specified | |
| Topic | Health: medical history, family history, smoking, drinking | |
| Mode of Administration | Postal | |
| Notes | Age: mostly 46‐65 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nakai 1997.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | People aged 40‐64 | |
| Comparisons | 1. Short questionnaire (4 pages) 2. Long questionnaire (8 pages) | |
| Outcomes | — | |
| Topic | Health: health status, health‐related practice, smoking status | |
| Mode of Administration | Postal | |
| Notes | Age: 40‐64 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Nakash 2007.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Adults with severe ankle sprain enrolled in the CAST trial of ankle supports, UK | |
| Comparisons | User‐friendly Trial Calendar of prompts and reminders for trial participants vs. no calendar | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (Foot and Ankle Outcome Score (FAOS), SF‐12 and EQ‐5D) | |
| Mode of Administration | Postal | |
| Notes | 30‐45 minutes. Follow‐up in the CAST trial was conducted at 4 weeks, 12 weeks and 9 months. We extracted response data for the 4‐week outcome. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | No | Neither participants nor personnel were blind to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Nakazawa 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 4812 bereaved family members, Japan | |
| Comparisons | Pen vs no pen; postal follow‐up including vs. excluding questionnaire | |
| Outcomes | First response (pen), final response (after reminder questionnaire or letter alone) | |
| Topic | Health (evaluation of end‐of‐life care) | |
| Mode of Administration | Postal | |
| Notes | Three questionnaires: Good Death Inventory (18 domains representing concepts important to a good death in a Japanese patient with cancer), the Care Evaluation Scale (10 domains representing concepts important to EOL care), and the Caregiving Consequences Inventory to evaluate caregiver burden | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response (pen), final response (after reminder questionnaire or letter alone) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Napoles‐Springer 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | African‐American or white, who were at least 50 years old, and had once visited the primary care practices of an academic health centre during the previous year | |
| Comparisons | 1. Advance notice letter 2. No advance letter |
|
| Outcomes | Response period within 2 weeks | |
| Topic | Health: patient satisfaction in adult ambulatory care | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Nathenson 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 405 elementary education teachers in a large urban school district in the northeastern United States | |
| Comparisons | Emphasis on incentive (conditional $25) vs. no emphasis; motivational appeal stresses altruism vs. other appeals (achievement, affiliation, reciprocity, commitment and consistency) | |
| Outcomes | e‐click and e‐completion | |
| Topic | Non‐health (research on how students learn mathematics) | |
| Mode of Administration | Web survey | |
| Notes | Emails contained a link to the OGAP/NSF assessment as well as a unique survey code to access the assessment. The first email was sent on a Thursday at approximately 6:05 a.m. If a teacher did not complete the survey by the following Monday afternoon, they were sent a second email under the same motivation appeal at approximately 6:05 a.m. that Tuesday. Teachers were randomised to receive one of six motivational appeals and were re‐randomised to receive a different appeal each subsequent week, conditional on not having completed the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | e‐click and e‐Comction reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Nederhof 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | All members of the general population of a medium‐sized Dutch town | |
| Comparisons | 1. Telephone pre‐notification 2. Mail pre‐notification | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nederhof 1983a.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Group of members of the general public in Leyden, Netherlands | |
| Comparisons | 1. Computer‐printed address label 2. Handwritten address label 3. Ballpoint pen worth $0.35 4. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes towards suicide | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nederhof 1983b.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Group of members of the general public in Leyden, Netherlands | |
| Comparisons | 1. Computer‐printed address label 2. Handwritten address label |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes about females social roles and vegetarianism | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nederhof 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Biotechnologists living in the Netherlands | |
| Comparisons | 1. Graphic illustration on cover of questionnaire largely in white 2. Graphic illustration on cover of questionnaire largely in black | |
| Outcomes | Response period not specified | |
| Topic | Health: development in biotechnology in the Netherlands | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Neider 1981a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A sample of training and development directors who were members of the American Association for Training and Development | |
| Comparisons | 1. Hand‐addressed outgoing envelope 2. Typed outgoing envelope 3. Computer‐generated label on outgoing envelope | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Neider 1981b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A sample of Class I and II common carriers | |
| Comparisons | 1. Hand‐addressed outgoing envelope 2. Typed outgoing envelope 3. Computer‐generated label on outgoing envelope | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nesrallah 2014.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Practising nephrologists, Canada | |
| Comparisons | Non‐monetary incentive ($40 charitable donation) vs. no incentive | |
| Outcomes | Response after 4 weeks (2 reminders) | |
| Topic | Health (nephrologists' attitudes toward home dialysis) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. Pre‐notification, invitation, first reminder, and final reminder letters were sent by email to both groups simultaneously over a 4‐week period. Letters were identical for both groups except for the following phrase: "By completing the survey, and in compensation for your time, a charitable donation of $40 will be made, on your behalf, to the Kidney Foundation of Canada, by our study sponsors." | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 4 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Nevin 1975a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of university halls (US) | |
| Comparisons | 1. Given deadline of 5 days 2. Given deadline of 7 days 3. Given deadline of 9 days 4. No deadline given | |
| Outcomes | — | |
| Topic | Non‐health: attitudes about residence halls | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nevin 1975b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Non‐responders to earlier survey of university hall residents | |
| Comparisons | 1. Follow‐up letter with casual approach 2. Follow‐up letter with veiled threat | |
| Outcomes | Response within 18 days | |
| Topic | Non‐health: attitudes about residence halls | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Newby 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Businesses listed in Perth, Western Australia | |
| Comparisons | 1. Monetary incentive worth A $20 2. Pre‐notification by telephone 3. Control |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes and expectations of the self‐employed | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Newland 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in electoral register (Southampton, UK) | |
| Comparisons | 1. First‐class stamp on outgoing envelope; first‐class stamp on return envelope; white envelopes
2. Second‐class stamp on outgoing envelope; second‐class envelope on return; white envelope
3. Second‐class frank on outgoing envelope; second‐class business‐reply return envelope; white envelopes
4. First‐class stamp on outgoing envelope; first‐class stamp on return envelope; brown envelopes
5. Second‐class stamp on outgoing envelope; second‐class envelope on return; brown envelope
6. Second‐class frank on outgoing envelope; second‐class business‐reply return envelope; brown envelopes Follow up at 2 and 16 weeks, including another copy of the questionnaire |
|
| Outcomes | — | |
| Topic | Health: details of headache and accompanying symptoms, general health, demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nichols 1966.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | College students who had returned a similar questionnaire 1 year previously | |
| Comparisons | 1. Follow‐up postcard after 3 days; further follow‐up mailings 2. Not sent postcard after 3 days; further follow‐up mailings | |
| Outcomes | Response within 120 days | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Nichols 1988.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Individuals listed on the electoral roll (Southampton, UK) | |
| Comparisons | 1. Information booklet sent 5 weeks before questionnaire 2. No information booklet sent | |
| Outcomes | Response period not specified | |
| Topic | Health: nutritional health education leaflet | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Nicolaas 2015.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Patients registered with a GP practice, UK | |
| Comparisons | Pre‐notification letter vs. none Reminder postcard vs. none Shorter vs. longer questionnaire | |
| Outcomes | Final response (2 reminders) | |
| Topic | Health (the GP Patient Survey; patient experiences and attitudes) | |
| Mode of Administration | Postal | |
| Notes | 8 pages (4 pages in shorter version). Two reminder packs, each comprising a letter and a copy of questionnaire, sent at monthly intervals to those not yet replying. Patients could complete survey on paper, online or by phone helpline. Pre‐notice letter was sent about one week before the first questionnaire mailing. Postcard reminder was sent to all sample members one week after the initial questionnaire mailing. Could not evaluate the effect of re‐designed cover letter as it included multiple components (i.e. shorter, giving prominence to the NHS England logo, using a high‐status signatory, and including different motivational statements); hence, we only evaluated the pre‐notification letter and the reminder postcard. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Noel 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 4638 primary care physicians from the American Medical Association Physician Masterfile | |
| Comparisons | No incentive vs. smaller monetary incentive (US $2) vs. slightly larger monetary incentive (US $5) vs. larger monetary incentive (US $10) | |
| Outcomes | Response after 178 days. Participants received one mailed and one telephone reminder (after 1 month). | |
| Topic | Health (physicians' use of electronic health record (EHR) systems) | |
| Mode of Administration | Postal | |
| Notes | Short screener (7 questions). Non‐respondents received a second screener mailing and were called to complete the screener over the phone after 1 month. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 1 month (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
O'Connor 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1200 elderly married people (65‐81 years) randomly selected through the Danish Central Person Register | |
| Comparisons | Shorter vs. longer questionnaire; certified delivery vs. standard; non‐monetary incentive (gift voucher 50DKr/$10) vs. none | |
| Outcomes | First response | |
| Topic | Health (depression, social support, coping style, adult attachment, life satisfaction, and personality factors). | |
| Mode of Administration | Postal | |
| Notes | 133 items in the short questionnaire vs. 318 items in the full questionnaire. The letter had a university letterhead and was personally signed by researcher. No reminders were sent out. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | No | Confounding: exclusion of sensitive material in the short questionnaire may also have increased response‐rate and data quality. |
Ogborne 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Health and social service professionals who had not responded to an earlier mailing | |
| Comparisons | 1. Second questionnaires sent 2. Telephoned by a research assistant | |
| Outcomes | Response period not specified | |
| Topic | Health: evaluation of innovative addiction assessment/referral programme | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Olivarius 1995.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | GPs and specialists or consultants (Nordic countries) | |
| Comparisons | 1. Questionnaire received on a Friday (GPs)
2. Questionnaire received on a Monday (GPs)
3. Questionnaire received on a Friday (Specialists)
4. Questionnaire received on a Monday (Specialists) Follow‐up sent after 14 and 28 days |
|
| Outcomes | Response within 60 days | |
| Topic | Health: importance of GPs, treatment of general diseases | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Olsen 2012.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | 2400 adults randomly drawn from the Norwegian Population Register | |
| Comparisons | Non‐monetary incentive (3 EUR scratch card) vs. no incentive | |
| Outcomes | Response after 6 weeks (one reminder) | |
| Topic | Health (oral health) | |
| Mode of Administration | Postal | |
| Notes | 14 questions. A reminder‐questionnaire was mailed to non‐respondents in both groups after 6 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Random allocation: alternation |
| Allocation concealment? | No | Random allocation: alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 6 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Osborne 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General practitioners | |
| Comparisons | 1. Received pre‐contact telephone call from non‐medical research assistant 2. No pre‐contact | |
| Outcomes | Response within 60 days | |
| Topic | Health: views about pathological test ordering | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pace 2020.
| Study characteristics | ||
| Methods | Quasi‐randomisation: alternating allocation | |
| Data | 303 primary care providers (PCPs) nominated by study participants to disclose their BRCA1/2 mutation results obtained through the BFOR (BRCA Founder OutReach) study, US | |
| Comparisons | Unconditional non‐monetary incentive ($50 cheque) vs. unconditional non‐monetary incentive ($50 cash card) | |
| Outcomes | Response after 1st and 2nd reminders (3 and 6 weeks) | |
| Topic | Health (primary care physicians' knowledge of BRCA1/2 mutation and opinions on use of genetic testing in their practices) | |
| Mode of Administration | Postal (electronic option) | |
| Notes | 4 pages (< 10 mins). Each initial survey mailing included a personalised cover letter, and an unconditional $50 incentive. First and second reminders were sent via mail roughly 3 and 6 weeks, respectively, after the initial mailing. These reminders contained personalised letters, a second copy of the survey, and an SAE. Because cheques and registered cash cards can be tracked more easily than cash, they may be preferable to cash or non‐registered cash cards for institutional accounting. Registered cash cards have the additional benefits of being logistically more feasible and efficient than cheques, which must be generated individually for each clinician surveyed. The cash cards were reloadable debit cards that required activation by the study managers before use. GPs received instructions accompanying the card informing them that if they wished to activate the cash card they had to email a study manager with their card number and request card activation. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Quasi‐randomisation: alternating allocation |
| Allocation concealment? | No | Quasi‐randomisation: alternating allocation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Paolillo 1984.
| Study characteristics | ||
| Methods | Random allocation: systematic division | |
| Data | A sample of professionals from the midwestern US | |
| Comparisons | 1. Control group 2. $1 enclosed with questionnaire 3. $2 promised on return of questionnaire 4. Entry into a lottery for a cash prize promised on return of questionnaire | |
| Outcomes | Response within 6 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Parasuraman 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Commercial marketing research firms (US) | |
| Comparisons | 1. Brief cover letter 2. Detailed cover letter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: aspects of marketing research | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Parker 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Participants at 3‐month follow‐up in UK FROST trial of treatments for frozen shoulder in a hospital setting, UK | |
| Comparisons | SMS pre‐notification on day of mailing vs. SMS post‐notification 4 days following mailing | |
| Outcomes | Final response | |
| Topic | Health (Oxford Shoulder Score) | |
| Mode of Administration | Postal | |
| Notes | Oxford Shoulder Score (OSS) ‐ 12 questions. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Parkes 2000a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adults aged 20‐74 years who are cases or controls in a Canadian case‐control study of cancer | |
| Comparisons | 1. Enclosure of brochure with questionnaire which expands on the information provided in the covering letter about the survey 2. No brochure | |
| Outcomes | — | |
| Topic | Health: tobacco exposure, diet, physical activity, use of medications, reproductive history | |
| Mode of Administration | Postal | |
| Notes | A reminder postcard, a reminder letter and second copy of the questionnaire and a follow‐up phone call were made 1‐2,4 and 6 weeks after the initial mailing, respectively, to non‐responders. Age: 20‐74 years |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Parkes 2000b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adults aged 20‐74 years who are controls in a Canadian case‐control study of cancer | |
| Comparisons | 1. No incentive 2. $2 sent with questionnaire 3. $5 sent with questionnaire | |
| Outcomes | — | |
| Topic | Health: tobacco exposure, diet, physical activity, use of medications, reproductive history | |
| Mode of Administration | Postal | |
| Notes | A reminder postcard, a reminder letter and second copy of the questionnaire and a follow‐up phone call were made 1‐2,4 and 6 weeks after the initial mailing, respectively, to non‐responders. Age: 20‐74 years |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Parsons 1972a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Alumni from a Masters in Business Administration program at a private university | |
| Comparisons | 1. Pre‐notification 2. No pre‐notification | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: correlation between political opinions and religious belief | |
| Mode of Administration | Postal | |
| Notes | Allocation concealment ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Parsons 1972b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Leaders of 2 religious sects (US) | |
| Comparisons | 1. Pre‐notification 2. No pre‐notification | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: correlation between political opinions and religious belief | |
| Mode of Administration | Postal | |
| Notes | Allocation concealment ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Patrick 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 3000 randomly‐selected undergraduate students, participants of the Student Life Survey at large university in the midwest, US | |
| Comparisons | Smaller unconditional monetary incentive ($2) plus a larger conditional monetary incentive ($10) vs. larger unconditional monetary incentive ($10) only | |
| Outcomes | Responses (e‐logins and e‐completions) after 4 reminders | |
| Topic | Health (college student substance use and related behaviours) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. Students received a mailed pre‐notification letter inviting them to participate and informing them that they would receive an email containing a link to the web‐based survey. Up to 4 reminder emails were sent to non‐responders. Participants were randomly assigned to a condition. However, we note that it is possible that students saw the invitation letters of other students and compared the incentive structures. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | No | It is possible that students saw the invitation letters of other students and compared the incentive structures. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Responses (e‐logins and e‐completions) after 4 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Patrick 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 4950 12th grade students who had completed the national Monitoring the Future (MTF) baseline survey in 2012 or 2013 but had not been selected to participate in the main MTF follow‐up. | |
| Comparisons | Mail‐only vs. mail push (mail, mail/web reminder) vs. web push (web, web/paper reminder) vs. web push + email augmentation | |
| Outcomes | Final response | |
| Topic | Health (substance use amongst adolescents and adults in the US) | |
| Mode of Administration | Postal/electronic | |
| Notes | 4 pages. Mail‐only: MTF control (standard protocol), with a phone prompt for non‐respondents Mail push: (mail with web reminder) participants were sent the selection letter, newsletter, advance letter, paper questionnaire with a cheque for $25, and a reminder postcard. Each mailing mirrored the MTF main study (i.e. MTF control). The mail push reminder letter reminded participants of the paper questionnaire already sent and gave option to complete the survey online. Non‐response phone calls to all those who had not yet returned a questionnaire provided information about the paper and web response modes. A final mailing included a paper questionnaire and web‐survey option Web push condition: (web with choice reminder) participants were sent the selection letter and newsletter that mirrored the MTF control group, except language implying a paper survey was removed. Web push participants were then sent an advance letter stating that next week they would be sent an invitation to complete an online survey. A week later, they were sent web survey login information (i.e. survey URL and PIN) and a check for $25. The reminder postcard was the same as MTF control except it requested they do the web survey. The reminder letter reminded participants to do the online survey, and the option of completing the enclosed paper questionnaire instead. Non‐response phone calls to all those who had not yet returned a questionnaire provided information about the paper and web response modes. A final mailing included a paper questionnaire and information about the web survey. Web push + email condition (i.e. what Millar and Dillman 2011 call email augmentation), had identical procedures to web push with the addition of emailed versions of the advance letter, web‐survey login information, reminder postcard, and reminder letter. Participants who did not provide a usable email address received the same protocol as web push. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Paul 2005.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Pharmacists in NSW, Australia, who had sold nicotine replacement therapy (NRT) or bupropion in the last month | |
| Comparisons | 1. Gift voucher worth A$20 2. No voucher |
|
| Outcomes | First response and response after 6 weeks (2 reminders) | |
| Topic | Health (attitudes toward supporting smoking cessation in the pharmacy environment, and training received regarding nicotine replacement therapy and smoking cessation) | |
| Mode of Administration | Postal | |
| Notes | 28 items, 10 minutes to complete. The pharmacist in charge of each selected pharmacy was mailed a primer postcard followed by the questionnaire within the following 2 weeks. Non‐responders received one print reminder 4 weeks after receipt of the questionnaire. Telephone reminders were provided a further 2 to 6 weeks later. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generation |
| Allocation concealment? | Yes | Random allocation: random number generation |
| Blinding of participants and personnel | No | Neither participants nor personnel were blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response and response after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Pearson 2003.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | Alumni at Stanford University | |
| Comparisons | 1. Salutation ‐ generic (Dear Stanford Alumni) 2. Salutation ‐ familiar personalisation (Dear James) 3. Salutation ‐ familiar personalisation without the dear (James) 4. Salutation ‐ formal personalised (Dear Mr. Bond) |
|
| Outcomes | Response within 27 days | |
| Topic | Non‐health: Stanford University's logos, image, and branding | |
| Mode of Administration | Electronic: Online survey | |
| Notes | Method of allocation ascertained through contact with author; age: mostly 30‐49 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Peck 1981.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Men and women who had been high school juniors in spring 1973 (US) | |
| Comparisons | 1. Prepaid $3 incentive 2. Promised $3 incentive 3. No incentive | |
| Outcomes | Response within 5 weeks | |
| Topic | Non‐health: career plans, labour market, post‐high school educational experience | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pedersen 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 6162 adult members of a Danish non‐probability online panel survey | |
| Comparisons | Cash prize lottery incentive (300 DKK) vs. conditional charitable donation (3 DKK or 10 DKK) vs. egotistic text appeal vs. altruistic text appeal vs. no incentive | |
| Outcomes | Response within 2 weeks | |
| Topic | Various topics (e.g. healthcare, finance, education) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire not described. Email encouraging participation in a brief online survey. No further description of reminders etc. provided | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Pedrana 2008.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1550 general practitioners in Victoria, Australia | |
| Comparisons | Registered mail vs. standard mail | |
| Outcomes | Response after 2 reminders (8 weeks) | |
| Topic | Health (antenatal screening practice) | |
| Mode of Administration | Postal | |
| Notes | 10 questions. Reminder letters with a questionnaire and an SAE were sent to non‐responders after 4 weeks. A second reminder was sent to remaining non‐responders after a further 4 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Pejtersen 2020.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (Rand function in SAS) | |
| Data | Children and young people (aged 11‐28) from families with severe social problems, Denmark | |
| Comparisons | Unconditional non‐monetary incentive (Euro 15 voucher) vs. no incentive | |
| Outcomes | Response after 13 weeks (one reminder) | |
| Topic | Health (Strengths and Difficulties Questionnaire) | |
| Mode of Administration | Postal | |
| Notes | Approx. 90 items. The questionnaire was sent to both the intervention group and the control group together with a cover letter and an SAE. Addresses on envelopes were handwritten. After 3 weeks, non‐responders in both groups were sent a reminder together with a new copy of the questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Rand function in SAS) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (Rand function in SAS) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 13 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Perneger 1993.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Young adults enrolled in various insurance plans (US) | |
| Comparisons | 1. No incentive
2. Reminder card
3. Money offer
4. Both incentives Follow‐up with the incentive found to be best after 14 days |
|
| Outcomes | Response within 80 days | |
| Topic | Health: health status, risk‐taking behaviours, utilisation of health services, satisfaction with healthcare, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; age: mostly 26‐30 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Perry 1974.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Respondents to a previous questionnaire | |
| Comparisons | 1. Questionnaire sent in pre‐paid franked envelope 2. Questionnaire sent in hand‐stamped envelope | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Peters 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People aged 35 and over registered with a general practice (Bristol, UK) | |
| Comparisons | 1. Telephone number requested 2. Telephone number not requested | |
| Outcomes | Response period not specified | |
| Topic | Health: information about chronic conditions, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Peterson 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed in a telephone directory | |
| Comparisons | 1. University source (U); outgoing envelope (OE) metered; return envelope (RE) stamped; follow‐up postcard (FUP); address (A) typed 2. U; OE‐stamped; RE‐stamped; FUP; A‐typed 3. Business source (B); OE‐metered; RE‐stamped; FUP; A‐typed 4. B; OE‐stamped; RE‐stamped; FUP; A‐typed 5. U; OE‐metered; RE‐stamped; FUP; A‐label 6. U; OE‐stamped; RE‐stamped; FUP; A‐label 7. B; OE‐metered; RE‐stamped; FUP; A‐typed 8. B; OE‐stamped; RE‐stamped; FUP; A‐label 9. U; OE‐metered; RE‐stamped; no FUP; A‐typed 10. U; OE‐stamped; RE‐stamped; no FUP; A‐typed 11. B; OE‐metered; RE‐stamped; no FUP; A‐typed 12. B; OE‐stamped; RE‐stamped; no FUP; A‐typed 13. U; OE‐metered; RE‐stamped; no FUP; A‐label 14. U; OE‐stamped; RE‐stamped; no FUP; A‐label 15. B; OE‐metered; RE‐stamped; no FUP; A‐label 16. B; OE‐stamped; RE‐stamped; no FUP; A‐label 17. U; OE‐metered; RE‐Business reply (reply); FUP, typed 18. U; OE‐stamped; RE‐reply; FUP; A‐typed 19. B; OE‐metered; RE‐reply; FUP; A‐typed 20. B; OE‐stamped; RE‐reply; FUP; A‐typed 21. U; OE‐metered; RE‐reply; FUP; A‐label 22. U; OE‐stamped; RE‐reply; FUP; A‐label 23. B; OE‐metered; RE‐reply; FUP; A‐label 24. B; OE‐stamped; RE‐reply; FUP; A‐label 25. U; OE‐metered; RE‐reply; no FUP; typed 26. U; OE‐stamped; RE‐reply; no FUP; A‐typed 27. B; OE‐metered; RE‐reply; no FUP; A‐typed 28. B; OE‐stamped; RE‐reply; no FUP; A‐typed 29. U; OE‐metered; RE‐reply; no FUP; A‐label 30. U; OE‐stamped; RE‐reply; no FUP; A‐label 31. B; OE‐metered; RE‐reply; no FUP; A‐label 32. B; OE‐stamped; RE‐reply; no FUP; A‐label | |
| Outcomes | Response within 30 days | |
| Topic | Non‐health: banking and financial attitudes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Petrovčič 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2500 members of an online community in Slovenia | |
| Comparisons | Email sent from senior authority (Chief Editor) vs. no sender specified Email contains plea for help vs. no plea Email stresses benefits for the community vs. no stress | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (the role of the online community in their coping with health‐related issues in terms of access to expert and peer support) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire contained a brief informed consent page and four main sections of questions. Median length 16.45 minutes to complete An initial email invitation was sent out to all members informing them of the study, asking them to participate, and providing them with a link to the web survey. Reminders for the second and third contact attempts to non‐responders at 78 and 160 hours |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Phillips 1951.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Graduates of Fisk University in the classes of 1924 and 1939 | |
| Comparisons | 1. Follow‐up by first‐class mail 2. Follow‐up by special delivery mail | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pirotta 1999.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General practitioners | |
| Comparisons | 1. Sent primer postcard 5 days before questionnaire 2. Not sent primer postcard before questionnaire | |
| Outcomes | Response within 60 days | |
| Topic | Health: not specified | |
| Mode of Administration | Postal | |
| Notes | Author contacted: additional unpublished data provided was slightly different to the published report; author data included | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pit 2013.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | GPs aged over 45 years, Australia | |
| Comparisons | Pen vs. no pen | |
| Outcomes | First response and final response (after 2 reminders ‐ 4 weeks) | |
| Topic | Non‐health (how to prolong the working lives of GPs) | |
| Mode of Administration | Postal/electronic | |
| Notes | 3 pages; participants were sent an invitation package consisting of a letter of support from the local GP Network, a study information letter, a questionnaire, an online survey web‐address, and an optional invitation to take part in an interview. Because the surveys were returned anonymously, completed surveys were taken as consent. Two reminders were sent 2 and 4 weeks after the initial invitation. The "nice pen" had a mountain view with clouds, the university's name, and a statement, "Doctors working on" printed on it. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Participants were blinded because they were not made aware in advance that the trial was carried out. The sequence allocation was not concealed from the project manager or the GP Network staff. However, participants were unaware of treatment allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response and final response (after 2 reminders ‐ 4 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Poe 1988.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Relatives of people who had died and whose death certificates had been filed in September and October 1984 | |
| Comparisons | 1. 'Don't know' boxes included 2. 'Don't know' boxes not included | |
| Outcomes | Response period not specified | |
| Topic | Health: healthcare in the last year of life, health practices, socioeconomics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Porter 2003a.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | Non‐applicant high school students | |
| Comparisons | 1. Control 2. $50 gift voucher for Amazon.com 3. $100 gift voucher for Amazon.com 4. $150 gift voucher for Amazon.com 5. $200 gift voucher for Amazon.com |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: application to college | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Porter 2003b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | Non‐applicant high school students | |
| Comparisons | 1. Salutations impersonal (e.g. Dear Student) 2. Salutations personal (e.g. Dear Jane) 3. Title of signatory, high (Director) 4. Title of signatory, low (Administrative assistant) 5. Sponsorship, low‐profile office (Office of Institutional Research) 6. Sponsorship, high‐profile office (Office of Admission) 7. Source of email address, office (e.g. surveyresearch@institution.edu) 8. Source of email address, person (e.g. jsmith@institution.edu) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceptions of the college and the reasons for not applying | |
| Mode of Administration | Electronic: Online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Porter 2005a.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | High school seniors who did not apply to college | |
| Comparisons | 1. Subject‐line ‐ blank 2. Subject‐line ‐ survey 3. Subject‐line ‐ liberal arts university 4. Subject‐line ‐ request for assistance 5. Subject‐line ‐ survey, request for assistance 6. Subject‐line ‐ liberal arts university, request for assistance 7. Subject‐line ‐ liberal arts university, survey 8. Subject‐line ‐ liberal arts university, request for assistance, survey |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceptions of the school | |
| Mode of Administration | Electronic: online survey | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Porter 2005b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | Undergraduates currently enrolled at the institution | |
| Comparisons | 1. Subject‐line ‐ blank 2. Subject‐line ‐ survey 3. Subject‐line ‐ liberal arts university 4. Subject‐line ‐ request for assistance 5. Subject‐line ‐ survey, request for assistance 6. Subject‐line ‐ liberal arts university, request for assistance 7. Subject‐line ‐ liberal arts university, survey 8. Subject‐line ‐ liberal arts university, request for assistance, survey |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: abilities on various capabilities and types of knowledge | |
| Mode of Administration | Electronic: online survey | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Porter S 2003b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | Non‐applicant high school students | |
| Comparisons | 1. Selective statement in the email invitation 2. No selective statement in the email invitation 3. Mention of general deadline in at least 1 email 4. Mention of specific deadline in email 3 5. Mention of specific deadline in emails 2 and 3 6. Mention of specific deadline in emails 1,2, and 3 7. No general deadline 8. No specific deadline |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perceptions of the college and the reasons for not applying | |
| Mode of Administration | Electronic: online survey | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Pourjalali 1994.
| Study characteristics | ||
| Methods | Random allocation: random number table | |
| Data | Students who had participated in an investment game | |
| Comparisons | 1. Investigator perceived to be African‐American (AA); male investigator (MI); informal letter (IL); easier questions first (E1) 2. AA; MI; IL harder questions first (H1) 3. AA; female investigator (FI); IL; E1 4. AA; FI; IL; H1 5. AA; MI; formal letter (FL); E1 6. AA; MI; FL; H1 7. AA; FI; FL; E1 8. AA; FI; FL; H1 9. Investigator perceived to be Caucasian (Ca); MI; IL; E1 10. Ca; MI; IL; H1 11. Ca; FI; IL; E1 12. Ca; FI; IL; H1 13. Ca; MI; FL; E1 14. Ca; MI; FL; H1 15. Ca; FI; FL; E1 16. Ca; FI; FL; H1 17. Investigator perceived to be Hispanic (Hi); MI; IL; E1 18. Hi; MI; IL; H1 19. Hi; FI; IL; E1 20. Hi; FI; IL; H1 21. Hi; MI; FL; E1 22. Hi; MI; FL; H1 23. Hi; FI; FL; E1 24. Hi; FI; FL; H1 25. Investigator perceived to be 'foreign/alien' (Fo); MI; IL; E1 26. Fo; MI; IL; H1 27. Fo; FI; IL; E1 28. Fo; FI; IL; H1 29. Fo; MI; FL; E1 30. Fo; MI; FL; H1 31. Fo; FI; FL; E1 32. Fo; FI; FL; H1 | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: AT&T investment game | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; equal male and females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Powers 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | High school juniors | |
| Comparisons | 1. Feedback offered; long questionnaire 2. Feedback offered; short questionnaire 3. No feedback offered; long questionnaire 4. No feedback, short questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: students' reaction to the test administration and/or to the preparatory materials for SAT | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pressley 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Marketing research directors | |
| Comparisons | 1. Dime incentive included
2. No incentive
3. Cartoons
4. No cartoons
5. Yellow questionnaire
6. Blue questionnaire
7. Green questionnaire
8. White questionnaire Factorial design Follow‐up sent to non‐respondents after 3 weeks |
|
| Outcomes | Response within 6 weeks. | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pressley 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Executives employed by organisations located throughout the US | |
| Comparisons | 1. Postscript; deadline 2. No postscript; deadline 3. Postscript; no deadline 4. No postscript; no deadline | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Pressley 1985.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Executives at VP‐level in firms employing more than 500 (US) | |
| Comparisons | 1. Mailed on Friday 2. Mailed on Monday 3. Coding handwritten in black ink 4. Coding in invisible ink 5. Coding was typed room number. 6. Telephone pre‐notification without incentive 7. Postcard pre‐notification with $0.10 incentive 8. Sent in window envelope 9. Sent in regular envelope | |
| Outcomes | Response within 2 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Price 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A random sample of African‐American women from a midwestern university minority alumni membership list | |
| Comparisons | 1. Race‐specific stamp on return envelope 2. General stamp on return envelope | |
| Outcomes | Response period not specified | |
| Topic | Health: cervical cancer | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Price 2003.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Public health educators and university professors in health education who did not respond to the second mailing | |
| Comparisons | 1. Signed postcard 2. Unsigned postcard |
|
| Outcomes | Response period not specified | |
| Topic | Health: health education skills | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Price 2010.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | 750 school nurses selected from the National Association of School Nurses membership database, US | |
| Comparisons | Cover letter signed by one researcher vs. cover letter signed by three researchers | |
| Outcomes | First response and final response after 2 weeks (one reminder) | |
| Topic | Health (perceptions and practices of schools assisting students in obtaining public health insurance) | |
| Mode of Administration | Postal | |
| Notes | 30 items; closed format; 4 pages. Two mailings; both used techniques to maximise response rate including; limiting questionnaire length, demographic questions at the end and first mailing included one dollar monetary incentive and personalised the letter. After 2 wks, the follow‐up mailing was sent with the appropriate covering letters to non‐responders. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Unclear | Exclusions reported |
| Selective reporting | Yes | First response and final response after 2 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Price 2014.
| Study characteristics | ||
| Methods | Random allocation: computer generated (STATA ralloc command) | |
| Data | Parents of children diagnosed with autism spectrum disorder | |
| Comparisons | Unconditional non‐monetary incentive (chocolate frog) vs. no incentive | |
| Outcomes | Response after 5 weeks (2 reminders) | |
| Topic | Health (experiences of a child's diagnosis of autism spectrum disorder) | |
| Mode of Administration | Postal | |
| Notes | Non‐responders within 3 weeks after the survey was posted received a further survey. After 2 weeks, received up to two telephone reminders thereafter. Survey pack containing information about the study, a 10‐page parent survey and a reply‐paid envelope | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (STATA ralloc command) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (STATA ralloc command) |
| Blinding of participants and personnel | Yes | Families and the researchers involved in data collection and entry were blinded to group allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after 5 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Pucel 1971.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Graduates (Minnesota, US) | |
| Comparisons | 1. Control 2. Pencil incentive 3. Coffee incentive 4. Green questionnaire 5. Pre‐notification letter 6. Pencil; green questionnaire 7. Pencil; pre‐notification letter 8. Pencil; green questionnaire; pre‐notification letter 9. Coffee incentive; green questionnaire 10. Coffee incentive; pre‐notification letter 11. Coffee incentive; green questionnaire; pre‐notification letter | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: criteria in counselling applicants to post‐high school vocational technical schools | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Puffer 2004.
| Study characteristics | ||
| Methods | Random allocation: using random number generation in SPSS | |
| Data | Women who returned the risk factor questionnaire for osteoporotic fracture | |
| Comparisons | 1. Single booklet ‐ 3 sections stapled together 2. Multiple booklet 3. SIngle‐sided 4. Double‐sided |
|
| Outcomes | Response period not specified | |
| Topic | Health: patient‐based outcome measures concerned with quality of life (SF‐36, EQ‐5D) | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rach 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 3275 participants in the German National Cohort | |
| Comparisons | Invitation including a study leaflet (brochure) vs. no study leaflet | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (general health status, height and weight, selected disease symptoms, use of medication, smoking, menopausal status, and the occurrence of diseases (diagnosed by a physician)) | |
| Mode of Administration | Postal | |
| Notes | 16‐page questionnaire. Invitations sent by mail and included a pre‐stamped return envelope, reminder letters sent at 3, up to 5 telephone calls at week 5‐9 and 2nd final reminder letter | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Rath 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Members of the Truth Initiative Young Adult Cohort (adults aged 18 years and older across both the online and offline populations in the US) who had completed one or more surveys prior to Wave 5 | |
| Comparisons | Reminder email including 'humor plus statistics' vs. reminder email including 'humor' only vs. standard email reminder | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (tobacco use) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. Those who did not respond to the first reminder were sent a second reminder. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Recklitis 2009.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Physicians from the Department of Internal Medicine at the University of Colorado Denver School of Medicine, US | |
| Comparisons | Monetary incentive ($20 bill) vs. non‐monetary incentive (USB flash drive) vs. both monetary ($20 bill) and non‐monetary (USB flash drive) incentives | |
| Outcomes | Final response after 2 weeks (one reminder) | |
| Topic | Health (Caring for Cancer Survivors) | |
| Mode of Administration | Postal/electronic | |
| Notes | The survey was printed in a colour booklet titled 'Caring for Cancer Survivors: Challenge and Opportunity'. The cover letter stated the survey was for primary care physicians and asked participants to complete the paper survey or an online version at a web address provided. Four days later, an email was sent to all potential participants for whom an email address was known, with an invitation to complete the survey online with a web link provided in the e‐mail. Two weeks after the initial mailing, a reminder letter and a second survey were sent to non‐responders by US mail, and a reminder email was sent to non‐responders with a known email address. The study design did not include a 'No incentive' arm. Survey packets including a cover letter, survey, and incentives were sent via Federal Express 2nd Day Airmail. Further details of the package were not reported. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Rego 2020.
| Study characteristics | ||
| Methods | Random allocation: computer generated (Microsoft Excel's RAND function) | |
| Data | Adults who cared for at least one child between 6 and 60 months, had access to their own mobile phone in three informal settlements in Mwanza, Tanzania | |
| Comparisons | Unconditional non‐monetary incentive ($0¬∑4 US airtime payment) vs. no incentive Shorter (1 question) vs. longer (3 questions) Daily vs. fortnightly messaging | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (infant diarrhoea rates) | |
| Mode of Administration | SMS survey | |
| Notes | 1 question vs. 3 questions. A text message, formatted according to the randomisation schedule, was sent via SMS message to participants between 10 a.m. and 11 a.m. on days due. If participants did not respond or complete the survey, they would receive two reminders, one after 4 h, and the second after a further 4 h. Responses were not accepted beyond 12 h from the initial message. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Microsoft Excel's RAND function) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (Microsoft Excel's RAND function) |
| Blinding of participants and personnel | Yes | Participants were blinded to their arm allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Reinisch 2016.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Members of the American Association of Plastic Surgeons | |
| Comparisons | Postal vs. electronic; smaller ($1 bill) vs. larger monetary incentive ($5 bill) | |
| Outcomes | Response after 2 weeks and response after 10 weeks | |
| Topic | Non‐health (authorship issues) | |
| Mode of Administration | Postal/electronic | |
| Notes | Follow‐up after 2 weeks with reminder. After further 2‐week period, the remaining non‐responders contacted by phone, offered survey by fax or mail or email. After 2 additional weeks (6 weeks after initial contact), non‐responders, regardless of group assignment, were mailed a survey. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Renfroe 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Participants of the AVID trial, USA | |
| Comparisons | 1. Mailed out by overnight express (OE); certificate of appreciation included (CA); mailed early (E); signature of Principal Investigator on cover letter (PI) 2. OE; CA; E; signature of Study Coordinator on cover letter (SC) 3. OE; CA; mailed late (L); PI 4. OE; CA; L; SC 5. OE; No CA; E; PI 6. OE; No CA; E; SC 7. OE; No CA; L; PI 8. OE; No CA; L; SC 9. Mailed out by regular mail (RM); CA; E; PI 10. RM; CA; E; SC 11. RM; CA; L; PI 12. RM; CA; L; SC 13. RM; No CA; E; PI 14. RM; No CA; E; SC 15. RM; No CA; L; PI 16. RM; No CA; L; SC | |
| Outcomes | Response period not specified | |
| Topic | Health: patient satisfaction | |
| Mode of Administration | Postal | |
| Notes | Mean age: 63; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Riesenberg 2006.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Designated Institutional Official (DIO) | |
| Comparisons | 1. Priority stamps worth $3.85 2. First‐class stamps worth $0.60 |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: employment ‐ demographics, identification of roles and responsibilities, competencies, training and experience required by the DIO | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rikard‐Bell 2000.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Dentists practising within the central Sydney area, Australia in 1997 | |
| Comparisons | 1. Advance telephone prompt 2. Advance letter prompt | |
| Outcomes | Response within 65 days | |
| Topic | Health: not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Rimm 1990.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Male health professionals who had not responded to a previous questionnaire | |
| Comparisons | 1. Certified mail
2. United Parcel Service
3. Window envelope with personal return address
4. Typed address
5. Handwritten address
6. Window envelope with computer printed address Factorial design |
|
| Outcomes | — | |
| Topic | Health: medical history, current diet and lifestyle habits | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; age: 40‐75; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Robb 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 3872 people aged 45‐59 years, registered with one of 4 general practices in southEast England | |
| Comparisons | Shorter vs. longer questionnaire No incentive vs. conditional non‐monetary incentive (£2.50 voucher) vs. conditional non‐monetary incentive (£5 voucher) vs. conditional non‐monetary incentive (£250 voucher lottery) | |
| Outcomes | Response after one reminder | |
| Topic | Health (health and attitudes towards bowel cancer screening) | |
| Mode of Administration | Postal | |
| Notes | Shorter questionnaire of 4 A4 pages or longer one of 7 A4 pages. Participants were mailed a letter from their inviting GP, the study questionnaire, and a freepost reply envelope. Non‐responders were sent a reminder questionnaire after approximately 2 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Roberts 1978.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | General practitioners who were members of the American Dental Association | |
| Comparisons | 1. Personalised; social appeal; deadline 2. Personalised; social appeal; no deadline 3. Personalised; no social appeal; deadline 4. Personalised; no social appeal; no deadline 5. Not personalised; social appeal; deadline 6. Not personalised; social appeal; no deadline 7. Not personalised; no social appeal; deadline 8. Not personalised; no social appeal; no deadline | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Informed that allocation concealment was adequate | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Roberts 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adults listed on a family health services authority register who had not responded to a previous questionnaire | |
| Comparisons | 1. First reminder was another copy of questionnaire 2. First reminder was a postcard | |
| Outcomes | Response period not specified | |
| Topic | Health: health and lifestyle | |
| Mode of Administration | Postal | |
| Notes | Age: 16‐70 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roberts 1994.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Nurses (Auckland, New Zealand) | |
| Comparisons | 1. Brown re‐usable envelope out; brown re‐usable envelope return
2. Brown re‐usable envelope out; white non‐reusable envelope return
3. White non‐reusable envelope out; brown re‐usable envelope return
4. White non‐reusable envelope out; white non‐reusable envelope return Reminders sent using the same envelope combination as initially allocated |
|
| Outcomes | Response period not specified | |
| Topic | Health: prevalence of back pain | |
| Mode of Administration | Postal | |
| Notes | Mean age: 37.5 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roberts 2000.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 1000 English women aged 40 to 65 years | |
| Comparisons | 1. Entry into lottery for prize draw of £50 on response 2. Direct payment of £5 on response 3. Entry into lottery and direct payment of £5 on response 4. No incentive | |
| Outcomes | Response within 3 months | |
| Topic | Health: menopause services | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roberts 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | General practices in the North and West Birmingham area | |
| Comparisons | 1. Lottery to win high street shopping voucher worth £100 2. Control |
|
| Outcomes | Response period not specified | |
| Topic | Health: prevalence of IBS (Irritable Bowel Syndrome) using SF‐36, Rome II criteria | |
| Mode of Administration | Postal | |
| Notes | Mean age: 48 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Robertson 1978.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A systematic sample of Denver area residents listed in the Metropolitan area phone directory | |
| Comparisons | 1. Control; no incentive 2. Promise of $1 cash on return of questionnaire 3. Promise of $1 donation to charity on return of questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Robertson 2005.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Australian general practitioners and medical specialists | |
| Comparisons | 1. $ AU 2 scratch lottery ticket 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Heath: exploring new drug use by GPs and medical specialists | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Rodgers 2018.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Men and women aged over 65 who have fallen and live in the community, UK | |
| Comparisons | Study newsletter vs. no newsletter Personalised (handwritten) Post‐it vs. less personalised (printed) Post‐it vs. no Post‐it | |
| Outcomes | Response after 6 weeks (2 reminders) | |
| Topic | Health (falls prevention in elderly adults) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. The newsletter was posted to participants 3 weeks prior to posting the 12‐month questionnaire. Those participants randomised to not receive the newsletter were sent this eight weeks after the questionnaire was sent out. Date postal questionnaires sent was recorded and non‐responders within 2 weeks were sent up to two standard reminders, 2 weeks apart, by post, text or email according to the participant's preference, followed by a telephone reminder 1 week later. The newsletter contained information regarding trial progress, including the geographical location and number of participants recruited and what happens at the end of the study. The newsletter was posted to participants 3 weeks prior to posting the 12‐month questionnaire. Those participants randomised to not receive the newsletter were sent this 8 weeks after the questionnaire was sent out. The Post‐it note was placed on the top right hand corner of the questionnaire. Participants who did not return their questionnaire within 2 weeks were sent up to two reminders, 2 weeks apart, by post, text or email according to the participant's preference, followed by a telephone reminder 1 week later. All participants received an unconditional £5 note with their final follow‐up. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Rolnick 1989.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Women with sexually transmitted diseases | |
| Comparisons | 1. Detailed questionnaire 2. Modified questionnaire | |
| Outcomes | Response within 2 months | |
| Topic | Health: gynaecological issues | |
| Mode of Administration | Postal | |
| Notes | Age: 18‐28 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Romney 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Community educators | |
| Comparisons | 1. Open‐ended format 2. Closed‐ended format | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: community educational needs assessment instrument | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ronckers 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Dutch patients treated for ENT condition between 1945 and 1981 | |
| Comparisons | 1. Short questionnaire (8 pages) 2. Long questionnaire (12 pages) 3. Standard consent form 4. Multi‐option consent form (choices with regard to participation in 3 phases of the overall study) |
|
| Outcomes | Response period not specified | |
| Topic | Health: female reproductive history, occupational exposures, and diet | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roscoe 1975.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Random sample of telephone customers | |
| Comparisons | 1. Long questionnaire; postcard reminder follow‐up 2. Long questionnaire; telephone reminder follow‐up 3. Short questionnaire; postcard reminder follow‐up 4. Short questionnaire; telephone reminder follow‐up | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: telephone behaviours, housing, mobility, demographics, socioeconomic characteristics | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rose 2007a.
| Study characteristics | ||
| Methods | Random allocation: using random numbers chart | |
| Data | Employees of a large international retailer in the US | |
| Comparisons | 1. $1 bill 2. No incentive |
|
| Outcomes | Response period within 10 days | |
| Topic | Non‐health: related to marketing skills, management, and leadership qualities | |
| Mode of Administration | Postal | |
| Notes | Surveys with incentives enclosed were identified by a one‐inch‐long, one‐fourth‐inch‐wide yellow highlighter mark within a half inch of both edges of the lower left corner of the back side of the survey. Also, one‐fourth inch of the non‐highlighted corner at the bottom of the survey was cut off. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rose 2007b.
| Study characteristics | ||
| Methods | Random allocation: using random numbers chart | |
| Data | Employees of a large health care organisation in the US | |
| Comparisons | 1. Low novelty ‐ plain bill 2. High Novelty ‐ bill with small star sticker or Sacagawea gold dollar coin 3. A penny bill 4. A quarter bill 5. A dollar bill 6. No incentive |
|
| Outcomes | Response within 21 days | |
| Topic | Non‐health: training needs | |
| Mode of Administration | Postal | |
| Notes | Surveys with incentives enclosed has a one‐inch‐long, one‐fourth‐inch‐wide highlighted mark within a half inch of both edges of the lower left corner of the back side of the survey. Packets with pennies had orange marks, packets with quarters had yellow marks, packets with paper dollars had blue marks, and packets with Sacagawea dollars had green highlighter marks. In addition, one‐fourth inch of the non‐highlighted corner at the bottom of the survey was cut off. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rosoff 2005a.
| Study characteristics | ||
| Methods | Random allocation: random block procedure | |
| Data | Childhood cancer survivors | |
| Comparisons | 1. Unconditional $10 bill 2. Conditional $10 bill |
|
| Outcomes | Response period not specified | |
| Topic | Health: health‐related behaviours amongst childhood cancer survivors and their parents | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rosoff 2005b.
| Study characteristics | ||
| Methods | Random allocation: random block procedure | |
| Data | Childhood cancer survivors | |
| Comparisons | 1. Unconditional $10 bill 2. Conditional $10 bill |
|
| Outcomes | Response period not specified | |
| Topic | Health: health‐related behaviours amongst childhood cancer survivors and their parents | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rosoff 2005c.
| Study characteristics | ||
| Methods | Random allocation: random block procedure | |
| Data | Parents of childhood cancer survivors | |
| Comparisons | 1. Unconditional $10 bill 2. Conditional $10 bill |
|
| Outcomes | Response period not specified | |
| Topic | Health: health‐related behaviours amongst childhood cancer survivors and their parents | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Wealth Accumulation Planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Financial Services: Environment and Professions | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Estate and Gift Tax Planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990d.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Wealth Accumulation Planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990e.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Economics | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990f.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Pensions and Other Retirement Plans | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990g.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Advanced Estate Planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990h.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Financial Statement Analysis | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990i.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Group Benefits and Social Insurance | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990j.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Planning for Business Owners and Professionals | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | ||
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990k.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Financial Statement Analysis | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990l.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Financial and Estate Planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990m.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Financial and Estate planning | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Roszkowski 1990n.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students studying Group Benefits and Social Insurance | |
| Comparisons | 1. Long questionnaire
2. Short questionnaire Follow‐up sent to non‐respondents of first mailing |
|
| Outcomes | — | |
| Topic | Non‐health: evaluation of financial courses | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rucker 1979a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students | |
| Comparisons | 1. Standard questionnaire
2. Matrix questionnaire Follow‐up sent to non‐respondents after 10 days |
|
| Outcomes | Response within 2 months | |
| Topic | Non‐health: attitudes towards purchasing clothes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rucker 1979b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Students | |
| Comparisons | 1. Standard questionnaire
2. Matrix questionnaire Follow‐up sent to non‐respondents after 10 days |
|
| Outcomes | Response within 1 month | |
| Topic | Non‐health: clothing attitudes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Rucker 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Graduates | |
| Comparisons | 1. Textiles student sponsor; no photo of person on cover letter
2. Textiles student sponsor; casually dressed person on cover letter
3. Textiles student sponsor; formal dressed person on cover letter
4. Textiles professor sponsor; no photo of person on cover letter
5. Textiles professor sponsor; casually dressed person on cover letter
6. Textiles professor sponsor; formal dressed person on cover letter
7. Animal science student sponsor; no photo of person on cover letter
8. Animal science student sponsor; casually dressed person on cover letter
9. Animal science student sponsor; formal dressed person on cover letter
10. Animal science professor sponsor; no photo of person on cover letter
11. Animal science professor sponsor; casually dressed person on cover letter
12. Animal science professor sponsor; formal dressed person on cover letter Postcard reminder and second questionnaire sent to non‐respondents at approximately bimonthly intervals |
|
| Outcomes | — | |
| Topic | Non‐health: furniture opinion | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Russell 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Chiropractors registered with the College of Chiropractors of Alberta | |
| Comparisons | 1. Unconditional $5 bill 2. No incentive |
|
| Outcomes | Response period not specified | |
| Topic | Health: immunisation beliefs and behaviours of chiropractors | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ryu 2006.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Detroit Area Study (DAS) 2001 | |
| Comparisons | 1. Cash ($5 bill) 2. In‐kind (set of passes to regional parks, or metro parks) |
|
| Outcomes | Response period not specified | |
| Topic | Health: quality of life in the Metropolitan Detroit Area | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Saal 2005.
| Study characteristics | ||
| Methods | Random allocation: using alternation | |
| Data | Inpatients admitted for elective surgery at the St. Gallen Cantonal Hospital | |
| Comparisons | 1. Questionnaire sent 1 week after discharge 2. Questionnaire sent 5 weeks after discharge 3. Questionnaire sent 9 weeks after discharge |
|
| Outcomes | Response period not specified | |
| Topic | Health: patients' assessment of anaesthesia care | |
| Mode of Administration | Postal | |
| Notes | Survey was conducted by an independent organisation, the Picker Institute | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Sahlqvist 2011.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | 1000 participants randomly selected from the UK electoral register | |
| Comparisons | More vs. less personalised; shorter vs. longer questionnaire | |
| Outcomes | First response | |
| Topic | Health (travel behaviour, physical activity and the environment) | |
| Mode of Administration | Postal | |
| Notes | The long questionnaire was 24 A4 pages and consisted of seven sections; the short questionnaire covered the same general constructs but was reduced to six sections and 15 A4 pages. Pre‐notification postcard for all groups, survey pack 1 week later with letter, information sheet, consent, questionnaire and freepost return envelope. After 2 weeks, non‐responders sent reminder postcard or reminder pack (depending on further randomisation). Conditional prize draw for £25 gift voucher for all participants and thank you postcard |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | Participants were blind to their allocation status and to the fact that these survey design factors were the subject of a randomised controlled trial. Study co‐ordinators charged with receipting the return of completed surveys were not aware of a respondent's allocation status in terms of personalisation and reminder type. Nonetheless, they could not be fully blinded to a respondents' allocation status due to the different lengths (and therefore weights) of the two questionnaires. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Sakshaug 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Public and private establishments that had previously participated in a Job Vacancy Survey and were registered as employing staff in at least one of 25 target professions | |
| Comparisons | Email invitation to web survey (T3 + T4) vs. postal (T1 + T2); postal vs electronic (T1 vs. T4) | |
| Outcomes | First response and response after one reminder | |
| Topic | Non‐health (factors that influence establishments‚ decision‐making process for filling job vacancies) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. All invitations were addressed to the human resources (HRs) office or managerial board of the establishments. The invitation letters included the salutation 'Dear sir or madam' (even in the case of personalised email addresses) in the hope that the invitation would be forwarded to an HR officer or any person responsible for hiring. Postal and email reminders were sent at the same time according to the assigned treatment group. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | First response and response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Salim Silva 2002.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 2 female Australian samples. Sample A ‐ current office workers at a university. Sample B ‐ patients seen by a consultant in rehab medicine | |
| Comparisons | 1. Telephone reminder 2. No telephone reminder | |
| Outcomes | — | |
| Topic | Health: musculoskeletal symptoms, health service utilisation, tobacco and alcohol consumption, social support, occupational history and job satisfaction, general health, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | Age: Mostly above 45 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Sallis 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians who had not responded to a previous questionnaire (Monterey County) | |
| Comparisons | 1. No incentive 2. Pencil incentive printed with an attractive design | |
| Outcomes | Response period not specified | |
| Topic | Health: not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Salvesen 1992.
| Study characteristics | ||
| Methods | Random allocation: using a table of random numbers | |
| Data | Mothers who had not responded to a previous questionnaire | |
| Comparisons | 1. Newspaper article with description of the study 2. No article sent with the questionnaire | |
| Outcomes | Response within 30 days | |
| Topic | Health: child's health ‐ hearing, vision | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Allocation was not concealed; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Sang‐Wook 2005.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SAS | |
| Data | Korean‐Vietnam veterans | |
| Comparisons | 1. Questionnaires sent via recorded delivery 2. Questionnaires sent via standard delivery 3. Stamped‐return envelope 4. Franked‐return envelope |
|
| Outcomes | Response period not specified | |
| Topic | Health: veterans socioeconomic and health status, medical check‐up | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Satia 2005.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 4276 African‐Americans aged 18 to 70 years, residing in 6 contiguous North Carolina counties (3 urban and 3 rural), from Department of Motor Vehicle rosters, US | |
| Comparisons | Culturally sensitive approach letter vs. generic; unconditional vs. conditional non‐monetary incentive; non‐monetary incentive vs. no incentive | |
| Outcomes | Response after one reminder (3 weeks) | |
| Topic | Health (cancer prevention) | |
| Mode of Administration | Postal with choice (mail, web, telephone) | |
| Notes | 11 pages; printed in black and pink colour ink and designed to be attractive and interesting to potential respondents; all responses designed to be categorical. All prospective participants were sent pre‐notification postcards followed by questionnaires; the enclosed approach letter and questionnaire cover page provided information on how to participate by telephone or Internet instead. Thus, respondents selected their preferred completion method. A reminder letter was sent 2‐3 weeks later with a toll‐free number to call for a replacement questionnaire or to complete the survey by telephone and the URL for the survey website. The culturally sensitive letter was similar to the generic version but was designed to increase respondents' ethnic/cultural identification with the study by including the principal investigator's picture to identify her as African‐American. The letter also noted the paucity of information on health issues specific to African‐Americans and stressed the potential benefit of participation to others. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported (but not by an assigned intervention group). |
| Selective reporting | Yes | Response after one reminder (3 weeks) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Sauerland 2002.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | All members of the association of German surgeons | |
| Comparisons | 1. Hernia and pain questionnaires sent together in 1 letter 2. Hernia questionnaire sent first, pain questionnaire sent 4 weeks later 3. Pain questionnaire sent first, hernia questionnaire sent 4 weeks later | |
| Outcomes | Response period not specified | |
| Topic | Health: perioperative pain management, surgical technique in incisional hernia repair | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Schmidt 2005.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in SPSS | |
| Data | Product Development and Management Association (PDMA) members | |
| Comparisons | 1. Certified mail on outward mailing 2. First‐class mail on outward mailing |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: development of new products by various organisations | |
| Mode of Administration | Postal | |
| Notes | — | |
Schmuhl 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Emergency medical services (EMS) providers with current certification in Utah, US | |
| Comparisons | Paper only vs. Web only vs. choice (paper or Web) | |
| Outcomes | Response within 30 days with 2 reminder postcards (mailed 2 weeks apart) | |
| Topic | Health (Utah Emergency Services for Children needs assessment) | |
| Mode of Administration | Postal and electronic (Web survey) | |
| Notes | The survey contained 31 questions (17 multiple‐choice, eight fill‐in‐the‐blank or check all, and six open‐ended) regarding the topics of availability of paediatric equipment, EMS educational opportunities, cultural needs, injury prevention, and children with special healthcare needs. Questionnaire package not described. The Web survey contained the same 31 questions presented in the same order as the paper survey. The main difference was the decision to make closed‐ended questions required, meaning that individuals could not move on to the next question without answering the current question. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | All participants were blinded to the different survey modes, and the surveys were anonymous. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported: 212 surveys were deemed undeliverable by the post office and, as a result, 1661 surveys were included in this study. |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Schwartzenberger 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 969 patients who underwent endoscopic carpal tunnel release | |
| Comparisons | Postal vs. electronic | |
| Outcomes | Response 1 year after surgery | |
| Topic | Health (patient‐reported outcomes 1 year following carpal tunnel release) | |
| Mode of Administration | Postal/electronic/telephone | |
| Notes | 23‐question survey. In the traditional mail cohort, the study questionnaire along with instructions and a self‐addressed return envelope were sent. Patients whose questionnaire was not returned by 4 weeks were sent a second mailing at that time with contents identical to the first and given another 4 weeks to respond. Patients who did not respond by 8 weeks were considered non‐responders.
In the email cohort, surveys were administered and collected data were managed using the Research Electronic Data Capture (REDCap) tools hosted at our institution. Patients were sent an email containing instructions to click on a link that automatically opened the Web‐based survey. Patients who had not responded to the first email by 4 weeks were sent a second identical email at that time and given another 4 weeks to respond. Patients who did not respond by 8 weeks were considered non‐responders. Telephone cohort not considered in this review |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response 1 year after surgery reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Schweitzer 1995.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | University staff employed for at least 6 years (Pennsylvania, US) | |
| Comparisons | 1. Non‐form fillers; paid in advance
2. Non‐form fillers; paid on completion
3. Form‐fillers; paid in advance
4. Non‐form fillers; paid on completion Reminder sent to non‐respondents after 4 weeks |
|
| Outcomes | — | |
| Topic | Health: knowledge, attitudes, and behaviours regarding the selection of employee health benefits | |
| Mode of Administration | Postal | |
| Notes | Age: 45‐48 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Scott 1957.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Women aged 60 years and over from poll tax exemption lists for Travis County, Texas, USA, 1954 | |
| Comparisons | 1. Preliminary letter received on Monday, questionnaire received on Tuesday 2. Preliminary letter received on Monday, questionnaire received on Friday 3. No preliminary letter, questionnaire received on Wednesday 4. No preliminary letter, questionnaire received on Saturday | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: occupational history, present income/pension payment | |
| Mode of Administration | Postal | |
| Notes | Age: above 60 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Scott 2011.
| Study characteristics | ||
| Methods | Random allocation: random numbers generated in STATA | |
| Data | Doctors undertaking clinical practice drawn from a national directory of all doctors in Australia | |
| Comparisons | Electronic vs. mailed personal invitation letter to web survey ('sequential mode') vs. choice (postal/electronic) | |
| Outcomes | Response after 3 weeks (one reminder) | |
| Topic | Non‐health (Balancing Employment and Life ‐workforce participation and its determinants amongst Australian doctors) | |
| Mode of Administration | Postal/electronic | |
| Notes | 8 sections; 4 slight varied versions for different doctor types. 58 questions in 8‐page booklet (specialists in training) to 87 questions in 13‐page booklet (for specialists) Survey invitation letters indicated the University of Melbourne and Monash University as responsible for the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random numbers generated in STATA |
| Allocation concealment? | Yes | Random allocation: random numbers generated in STATA |
| Blinding of participants and personnel | No | Neither personnel nor participants were blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 3 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Sebo 2017.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Community‐based GPs with a valid and available email address | |
| Comparisons | Postal vs electronic | |
| Outcomes | First response and final response after one (postal group) or two (Web group) reminders | |
| Topic | Health (GPs' preventive care activities) | |
| Mode of Administration | Postal vs. Web | |
| Notes | Questionnaire included 37 questions. The postal letters included a cover letter and a stamped return envelope. GPs were asked to send the completed questionnaires back to the research assistant. Participants in the Web‐based group received the same cover letter in a Web‐based format. GPs were asked to connect through a hyperlink and complete the online questionnaire. The paper questionnaire was designed first, closely following published recommendations for optimal survey content and layout. The Web‐based questionnaire was then created to be as similar as possible to the paper version, including regarding text formatting. Note that completion of all questions was not required before submission of the Web‐based questionnaire. Reminder messages (once for the postal group and twice for the Web‐based group) were sent at one‐month intervals. No monetary incentives were offered to the participating GPs. All community‐based GPs practising were eligible for the study, except those practising only complementary and alternative medicine. There were no other exclusion criteria. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
See Tai 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Patients who had not responded to a questionnaire (London, UK) | |
| Comparisons | 1. Questionnaire reminder 2. Telephone reminder | |
| Outcomes | Response period not specified | |
| Topic | Health: to evaluate the use of structural computerised prompts in their management using Asthma Symptoms Questionnaire & Client Satisfaction Questionnaire (for patients with asthma), and Well‐being Questionnaire and Diabetes Treatment Questionnaire (for patients with diabetes) | |
| Mode of Administration | Postal | |
| Notes | Mean age: telephone group ‐ 47.5 years; recorded delivery group ‐ 40 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Severi 2011a.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (Minim software) | |
| Data | Participants in the Txt2stop trial of smoking cessation support who were due follow‐up | |
| Comparisons | Stress benefits to society of participation‐up vs. no stress | |
| Outcomes | Response at 26 and 30 weeks | |
| Topic | Health (smoking) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described, package not described RCT evaluating the impact of providing information regarding the benefits to society of participation. In addition to the standard trial follow‐up procedures, the intervention group was sent written information on a refrigerator magnet by post, between 16 and 20 weeks after randomisation into the Txt2stop trial, followed by a mobile phone text message 3 days after theTxt2stop postal follow‐up questionnaire was sent. The text message said 'Be proud of yourself for helping medical research! Thank you for filling in the Txt2stop questionnaire.' |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Minim software) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (Minim software) |
| Blinding of participants and personnel | Yes | This was a single‐blind controlled trial, with those recording and assessing outcomes blind to the intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Severi 2011b.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (Minim software) | |
| Data | Participants in the Txt2stop trial of smoking cessation support who were due follow‐up | |
| Comparisons | Follow‐up telephone call vs. no call | |
| Outcomes | Final response | |
| Topic | Health (smoking) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described, package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (Minim software) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (Minim software) |
| Blinding of participants and personnel | Yes | This was a single‐blind controlled trial, with those recording and assessing outcomes blind to the intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Shackleton 1980.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Partially sighted school‐leavers aged between 17 and 20 years who had left schools for the visually handicapped during the previous academic year | |
| Comparisons | 1. £1 offered; previous examination 2. No incentive; previous examination 3. £1 offered; no examination 4. No incentive; no examination | |
| Outcomes | Response within 42 days | |
| Topic | Non‐health: occupational experience during 1st year after leaving the school | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; age: 17‐20 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Shah 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Patients aged 65 to 74 years in an inner London practice who had consulted within the last 2 years | |
| Comparisons | 1. Inclusion of questions on income; inclusion of consent form 2. Inclusion of questions on income; no consent form 3. No questions on income; inclusion of consent form 4. No questions on income; no consent form | |
| Outcomes | — | |
| Topic | Health: physical and mental health, social circumstances, social support, living arrangements, income | |
| Mode of Administration | Postal | |
| Notes | Age: 65‐74 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Shahar 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals who had declined to participate in a previous study | |
| Comparisons | 1. Additional letter with first mailing requesting an explanation for not participating 2. No letter | |
| Outcomes | Response within 14 weeks | |
| Topic | Health: general health, physical activity, smoking habits, list of chronic disease, demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Sharp 2006.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Participants from the TOMBOLA (Trial Of Management of Borderline and Other Low‐grade Abnormal smears) trial | |
| Comparisons | 1. Pen 2. No pen 3. First‐class dispatch 4. Second‐class dispatch 5. Freepost (business reply) envelope 6. Postage stamp envelope |
|
| Outcomes | Response period not specified | |
| Topic | Health: psychosocial impact of having a low‐grade abnormal cervical smear and its subsequent management | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Shaw 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Health System Minnesota enrollees aged 20‐80 years | |
| Comparisons | 1. $5 included in survey package 2. $2 included in survey package | |
| Outcomes | — | |
| Topic | Health: Digestive Health Status instrument (DHS I), SF‐36, HADS, comorbidity checklist, healthcare utilisation | |
| Mode of Administration | Postal | |
| Notes | Age: 20‐80 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Sheikh 1982.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 400 people who had completed an assessment course at an employment rehabilitation centre in London 1973‐1974 | |
| Comparisons | 1. Questionnaire including sensitive question on earnings 2. Same questionnaire as (1) without the sensitive question on earnings | |
| Outcomes | — | |
| Topic | Non‐health: employment | |
| Mode of Administration | Postal | |
| Notes | Mean age: 39 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Shin 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Faculty members in universities and 4 4‐year colleges in the United States | |
| Comparisons | 1. Personalised (P); anonymous (A); professional appeal (Prof); university sponsored (U) questionnaire 2. P; A; Prof; private research institute sponsored (PR) 3. P; A; personal appeal (Pers); U 4. P; A; Pers; PR 5. P; Nonanonymous (NA); Prof; U 6. P; NA; Prof; PR 7. P; NA; Pers; U 8. P; NA; Pers; PR 9. Not personalised (Not P); A; Prof; U 10. Not P; A; Prof; PR 11. Not P; A; Pers; U 12. Not P; A; Pers; PR 13. Not P; NA; Prof; U 14. Not P; NA; Prof; PR 15. Not P; NA; Pers; U 16. Not P; NA; Pers; PR | |
| Outcomes | Response within 7 weeks | |
| Topic | Non‐health: student evaluation of faculty instruction | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Shiono 1991.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians (US) | |
| Comparisons | 1. Pre‐notification letter; stamp on return envelope 2. Pre‐notification letter; return envelope franked 3. No pre‐notification letter; stamp on return envelope 4. No pre‐notification letter; return envelope franked | |
| Outcomes | ||
| Topic | Health: pregnancy amongst resident physicians | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Signorelli 2021.
| Study characteristics | ||
| Methods | Random allocation: online computer‐generated (Research Randomizer tool) | |
| Data | Childhood cancer survivors and parents of survivors < 16 years from 11 hospitals across Australia/New Zealand | |
| Comparisons | Non‐monetary incentive (USB stick with video invitation) vs. no incentive | |
| Outcomes | Returned questionnaires | |
| Topic | Health (health, well‐being, information needs and health‐related quality of life) | |
| Mode of Administration | Choice | |
| Notes | Questionnaire assessed participants' health/well‐being, information needs and health‐related quality of life (using the EQ‐5D‐5L); included clinical data, relapse history, age and demographic information; 30 mins completion Study invitation packages contained a signed invitation letter from each survivor's treating oncologist, an information sheet, a questionnaire, a reply‐paid envelope and a card with a web‐link to complete the questionnaire online, if preferred. Letter invitation (control) vs. letter plus video invitation on a USB stick from survivor/paediatric oncologist/researcher. We conducted up to 4 follow‐up reminder calls to non‐respondents, 2 weeks apart, after mailout of the initial invitation and resent invitation packages up to a further 2 times on request. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: online computer‐generated (Research Randomizer tool) |
| Allocation concealment? | Yes | Random allocation: online computer‐generated (Research Randomizer tool) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 4 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Simon 1967a.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Readers of a magazine published by a national industrial company | |
| Comparisons | 1. Personal letter 2. Form letter | |
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards a hospital insurance plan | |
| Mode of Administration | Postal | |
| Notes | Author contacted: unable to provide further details on randomisation | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Simon 1967b.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Readers of a magazine published by a national industrial company | |
| Comparisons | 1. Personal letter 2. Form letter | |
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards a hospital insurance plan | |
| Mode of Administration | Postal | |
| Notes | Author contacted: unable to provide further details on randomisation | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Simon 1967c.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Subscribers to a hospital insurance plan | |
| Comparisons | 1. Personal letter 2. Form letter | |
| Outcomes | Response period not specified | |
| Topic | Health: attitudes towards a hospital insurance plan | |
| Mode of Administration | Postal | |
| Notes | Author contacted: unable to provide further details on randomisation | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Sizmur 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Five NHS trusts (12,723 invited staff), all participating in the main NHS staff survey for 2015 using online methodology | |
| Comparisons | More email reminders vs. fewer Sent or signed by more well‐known person vs. less well‐known person Included statement that others had responded vs. no statement | |
| Outcomes | Final response after reminders | |
| Topic | Health (staff experience, including health and well‐being, personal development, harassment and bullying, engagement and satisfaction, and support from managers) | |
| Mode of Administration | Web survey | |
| Notes | 33 questions over 7 pages. Email reminders were sent approximately every 1.5 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported, but excluded from analysis |
| Selective reporting | Yes | Final response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Skinner 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Marketing professors, Canada | |
| Comparisons | 1. No incentive 2. $1 pre‐paid incentive 3. $1 promised incentive; respondent identified 4. $1 promised incentive; respondent not identified 5. $1 promised to charity | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: needs of Canadian instructors regarding an introductory marketing text | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Sletto 1940.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Former university students | |
| Comparisons | 1. 10‐page questionnaire; altruistic appeal in cover letter 2. 10‐page questionnaire; cover letter requesting help 3. 10‐page questionnaire; cover letter challenging participants to respond 4. 25‐page questionnaire; altruistic appeal in cover letter 5. 25‐page questionnaire; cover letter requesting help 6. 25‐page questionnaire; cover letter challenging participants to respond 7. 35‐page questionnaire (10 and 25‐page questionnaires); altruistic appeal in cover letter 8. 35‐page questionnaire (10 and 25‐page questionnaires); cover letter requesting help 9. 35‐page questionnaire (10 and 25‐page questionnaires); cover letter challenging participants to respond | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: vocational activities, needs, interest, socio‐civic activities | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Sloan 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Doctors of patients with cancer | |
| Comparisons | 1. University letterhead (UL); MD signatory (MD); handwritten note (HN)
2. Cancer agency letterhead (CL); MD; HN
3. UL; PhD signatory (PhD), HN
4. CL; PhD; HN
5. UL; MD; No HN
6. CL; MD; No HN
7. UL; PhD, No HN
8. CL; PhD, No HN NB: this was a letter requesting doctors to give consent for patients to be contacted and sent questionnaires. |
|
| Outcomes | Response period not specified | |
| Topic | Health: not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Smith 1985.
| Study characteristics | ||
| Methods | Random allocation: sequential sampling | |
| Data | Patients aged 40‐59 years registered with an urban general practice, UK | |
| Comparisons | 1. Questionnaire sent by general practitioner 2. Questionnaire sent by a doctor from the research unit | |
| Outcomes | Response within 9 weeks | |
| Topic | Health: Aggression scale, Social desirability scale, Fear survey schedule II, Situations evoking social anxiety scale, Social evaluative anxiety scale | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
So 2018.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated random sequence | |
| Data | 2000 primary care physicians from members of the Japan Primary Care Association | |
| Comparisons | Email subject emphasises lottery for an Amazon gift card worth 3000 yen vs. no subject emphasis on lottery Sending the invitation email on Tuesday vs. Friday | |
| Outcomes | e‐login and e‐completed | |
| Topic | Health (survey on evidence‐based medicine) | |
| Mode of Administration | Web survey | |
| Notes | DOCTOR study, participants were asked to complete a 2‐page online questionnaire about evidence‐based medicine. The questionnaire had 9 and 4 items, respectively, on the first and second pages. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated random sequence |
| Allocation concealment? | Yes | Random allocation: computer‐generated random sequence |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | e‐login and e‐completed reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Solnick 2020.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Trainees (n = 8485) from the Emergency Medicine Residents Association (EMRA) email list, US | |
| Comparisons | Conditional non‐monetary incentive vs. no incentive; larger non‐monetary incentive ($100 giftcard raffle) vs. smaller ($25 giftcard raffle) | |
| Outcomes | e‐login and e‐completion | |
| Topic | Non‐health (political beliefs survey sent to Emergency Medicine trainees) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire and package sent not described No incentive vs. conditional non‐monetary ($25 giftcard raffle) vs. conditional non‐monetary ($100 giftcard raffle) vs. conditional non‐monetary ($5 giftcard) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported; after the first send (4 emails bounced) |
| Selective reporting | Yes | e‐login and e‐completion reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Spry 1989a.
| Study characteristics | ||
| Methods | Random allocation: using a table of random numbers | |
| Data | Residences listed in the Haines Directory (San Diego, US) | |
| Comparisons | 1. Telephone pre‐notification; lottery entry offer 2. Telephone pre‐notification; no lottery offer 3. Postcard pre‐notification; lottery entry offer 4. Postcard pre‐notification; no lottery offer 5. No pre‐notification; lottery entry offer 6. No pre‐notification; no lottery offer | |
| Outcomes | Response period not specified | |
| Topic | Health: health and physical activity habits | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Randomisation not concealed; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Spry 1989b.
| Study characteristics | ||
| Methods | Random allocation: using a table of random numbers | |
| Data | Residences listed in the Haines Directory (San Diego, US) | |
| Comparisons | 1. Short questionnaire; lottery 2. Short questionnaire; no lottery 3. Long questionnaire; lottery 4. Long questionnaire; no lottery | |
| Outcomes | Response period not specified | |
| Topic | Health: health and physical activity habits | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Randomisation not concealed; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Spry 1989c.
| Study characteristics | ||
| Methods | Random allocation: using a table of random numbers | |
| Data | Residences listed in the Haines Directory who had not responded to a questionnaire (San Diego, US) | |
| Comparisons | 1. Promise of $5 when response 2. Promise of $1 when response 3. $1 bill enclosed 4. No incentive | |
| Outcomes | Response period not specified | |
| Topic | Health: health and physical activity habits | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author. Randomisation not concealed; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Stafford 1966.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | University students (Houston, US) | |
| Comparisons | 1. Pre‐notification letter sent 2. Pre‐notification telephone call made 3. No pre‐notification contact | |
| Outcomes | — | |
| Topic | Non‐health: collegiate clothing market | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Stange 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | All members of the class of 2006 of a small, highly selective liberal arts school, US | |
| Comparisons | Pen vs. no pen | |
| Outcomes | First response and response after 3 weeks (one reminder) | |
| Topic | Non‐health (perception of job/graduate school options) | |
| Mode of Administration | Postal | |
| Notes | 6 pages; 25 mins completion time. Included multiple measures of cognitive style, career choices, and demographics Pen or no pen with initial survey mailing, the non‐retractable ballpoint pen included the college logo and colours. A stamped, addressed return envelope was included. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | First response and response after 3 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Stapulonis 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Members from the Welfare‐to‐Work evaluation site at Chicago | |
| Comparisons | 1. Conditional $20 check 2. Conditional point‐of‐sale cards worth $20 |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: employment | |
| Mode of Administration | Electronic: Computer Assisted Telephone Interview (CATI) | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Starr 2015.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants of SUSPEND RCT of medical expulsive therapy for ureteric stone disease, willing to provide a mobile phone number or an email address from 24 UK sites | |
| Comparisons | SMS pre‐notification vs. no pre‐notification Email reminder (with URL to complete the questionnaire via Web) vs. postal reminder | |
| Outcomes | Responses at 4 weeks | |
| Topic | Health (patient‐reported outcomes in SUSPEND RCT, renal stones) | |
| Mode of Administration | Mixed | |
| Notes | Questionnaire not described. All participants randomly assigned to the intervention arm were sent an SMS text message pre‐notification of the de‐livery of the initial 4‐ and 12‐week questionnaires. Controls received no pre‐notification. Responses at 4 week time point included in this review. Non‐responders to the intervention arm received email with URL for online completion. Non‐responders to control arm received further copy by post. Both reminder types were generated 2 weeks after the initial questionnaire was sent. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | No | Owing to the nature of the intervention, it was not possible to blind the participants or trial office staff to allocation; however, the researchers remained blind. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported for pre‐notification and reminder comparisons |
| Selective reporting | Yes | Responses at 4 weeks and at 12 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Stem 1984a.
| Study characteristics | ||
| Methods | Random allocation: using random number table | |
| Data | Students | |
| Comparisons | 1. Randomised response model 2. Direct questions |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: cheating behaviours during exams | |
| Mode of Administration | Postal | |
| Notes | — | |
Stem 1984b.
| Study characteristics | ||
| Methods | Random allocation: using random number table | |
| Data | Automobile sales licence holders | |
| Comparisons | 1. Randomised response model 2. Direct questions |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: automobile selling practices | |
| Mode of Administration | Postal | |
| Notes | — | |
Stevens 1975.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Graduates from a southern university (US) | |
| Comparisons | 1. Pre‐coded questionnaire 2. Questionnaire not pre‐coded | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: job hunting experience | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Stolzmann 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 300 veterans randomly selected from those who had received services at a mental health clinic in the Department of Veterans Affairs, US | |
| Comparisons | Lean (48) vs. medium (85) vs. maximum (127) questionnaire length | |
| Outcomes | Response after 4 weeks (2 reminders) | |
| Topic | Health (healthcare quality and satisfaction surveys in veteran populations) | |
| Mode of Administration | Postal | |
| Notes | Questionnaires 48‐127 items; lean (48 questions), medium (85 items) and maximum (127 items). Standardised measures of healthcare quality, satisfaction, and outcomes in addition to demographic questions. Survey packet consisted of a cover letter with instructions, the survey, and a pre‐paid envelope for the returned questionnaire. Non‐respondents received up to two follow‐up contacts, mailed at 2‐week intervals. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 4 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Streiff 2001.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Randomly selected members of the American Society of Hematology | |
| Comparisons | 1. Business reply envelope 2. Stamped return envelope | |
| Outcomes | Response within 3 months | |
| Topic | Health: diagnosis and treatment of polycythaemia Vera | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Subar 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | 900 control participants from 3 centres in the prostate, lung, colorectal and ovarian cancer screening trial | |
| Comparisons | 1. Diet history questionnaire ‐ 36 pages 2. Food frequency questionnaire ‐ 16 pages | |
| Outcomes | — | |
| Topic | Health: food frequency questionnaire, diet history questionnaire | |
| Mode of Administration | Postal | |
| Notes | Age: 55‐74 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Sutton 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Business customers who had taken advantage of an earlier rebate programme | |
| Comparisons | 1. Pre‐notification postcard; prior telephone call 2. Pre‐notification postcard; no prior telephone call 3. No pre‐notification postcard; no prior telephone call 4. No pre‐notification postcard; no prior telephone call | |
| Outcomes | Response period within 43 days | |
| Topic | Non‐health: customer reaction to energy rebate programme | |
| Mode of Administration | Postal | |
| Notes | Author contacted: reported adequate allocation concealment | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Suzer‐Gurtekin 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | A sample of residential addresses selected from the Marketing Systems Group (MSG) US Postal Service Computerized Delivery Sequence File | |
| Comparisons | (concurrent) Choice between postal or online questionnaire at the first mailing vs. Web‐only at first mailing (web push); prepaid $5 incentive vs. no incentive | |
| Outcomes | Response after reminders | |
| Topic | Non‐health (University of Michigan's Surveys of Consumer attitudes and expectations) | |
| Mode of Administration | Postal and electronic | |
| Notes | 20‐page booklet; large type Advance letter first, then the questionnaire mailing, then a reminder postcard, then a second questionnaire mailing, and a final reminder postcard. In the concurrent web‐mail design, a cover letter in the first questionnaire mailing included a URL. In the web‐intensive design, a separate web survey invitation letter followed the advance letter with a survey URL. The web survey letter also mentioned a paper questionnaire would be sent in a forthcoming mailing. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Svensson 2012.
| Study characteristics | ||
| Methods | Cluster‐randomisation by company: intervention groups applied wholly to each company of employees | |
| Data | 3876 employees (18‐65 years) at four companies in the Swedish railway sector | |
| Comparisons | Low (<= 6) vs. medium (7‐9) vs. high (> 9) numbers of reminders | |
| Outcomes | Final response | |
| Topic | Health (lifestyle habits, i.e. diet, sleep, physical activity, stress, and smoking) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. 2 email messages, (pre‐notification invitation and URL to questionnaire), sent to all participants
Reminders were given in three amounts, categorised as follows: (1) low amount of reminders: <= 6 reminders, (2)medium amount of reminders: 7‐10 reminders, and (3) high amount of reminders: > 10 reminders 3876 employees were emailed a baseline web‐based lifestyle questionnaire. 9 months later, follow‐up questionnaire sent. 4 and 11 email reminders were sent at baseline and follow‐up, respectively. Additional reminders (media articles, flyers, SMS ) also administered. Reminders (emails + additional) were given in low (<= 6 reminders), medium (7‐9 reminders) or high amount (> 9 reminders). |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Final response reported in full |
| Other sources of bias | No | Randomisation was at company level: the results were not adjusted for clustering. |
Svoboda 2001.
| Study characteristics | ||
| Methods | Random allocation: central randomisation | |
| Data | Head injured adults in the CRASH trial (Czech Republic) | |
| Comparisons | 1. 1‐page questionnaire 2. 3‐page questionnaire | |
| Outcomes | Response within 3 months | |
| Topic | Health: disability after traumatic brain injury | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Swan 1980.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals who had not responded to an earlier questionnaire | |
| Comparisons | 1. Follow‐up letter only 2. Follow‐up letter and questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: perception of educational needs for the real estate profession, sale management practices, business planning, information about respondents' firm | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Szelényi 2005.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 250 third‐year undergraduate students at 47 colleges, US | |
| Comparisons | Monetary incentive vs. no incentive Larger ($5) vs. smaller ($2) monetary incentive | |
| Outcomes | Response after one reminder | |
| Topic | Non‐health (development in spirituality ‐ students perspectives on issues of meaning, purpose, and spirituality, plus college experiences) | |
| Mode of Administration | Postal | |
| Notes | The College Students' Beliefs and Values Survey. 4 pages, 234 items. Advance notification postcard, followed 2 weeks later by a mailed questionnaire. Two weeks after the first wave of surveys was mailed to students, a subset of students received an email reminder. Subsequently, a second wave of surveys (without the unconditional monetary incentives) was sent to non‐respondents. To explore the impact of differential monetary incentives, institutions were categorised by type (4‐year college versus university), control (public versus private), religious affiliation (Catholic college versus other religiously affiliated college), and selectivity (based on the average composite SAT score of the entering class). Within each category, schools were randomly assigned to one of three incentive groups ($0, $2, or $5). These monetary incentives were included with the initial survey packet. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | No | Cluster‐randomised trial, with college the unit of randomisation. Possible effects due to clustering were not reported. |
Szirony 2002.
| Study characteristics | ||
| Methods | Random allocation: using random table of numbers | |
| Data | Faculty members from the top 100 graduate degree granting institutions in Nursing | |
| Comparisons | 1. Cover letter signed by a graduate student 2. Cover letter signed by a faculty member |
|
| Outcomes | Response period not specified | |
| Topic | Health: publication, authorship, reporting of research results, funding, demographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Tai 2018.
| Study characteristics | ||
| Methods | Random allocation: random number generator | |
| Data | Healthcare workers who volunteered to receive information regarding future studies about influenza, with both email and a postal address, in Toronto, Canada | |
| Comparisons | Email invitation to web survey vs. postal invitation Shorter vs. longer Open‐ended questions vs. close‐ended questions | |
| Outcomes | Final response after one reminder | |
| Topic | Health (adverse events following immunisation with influenza vaccine) | |
| Mode of Administration | Web survey | |
| Notes | Shorter contained 24 questions, longer contained 28 questions; open‐ended version contained 5 open‐ended questions (short version), 6 open‐ended questions (long version). Each invitation was personalised (e.g. 'Dear Jane') and contained a URL to the survey, a brief introduction to the study to increase salience. Reminder emails were sent to all non‐respondents 7 days after the initial email while reminder letters were sent 14 days after the initial letter. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator |
| Allocation concealment? | Yes | Random allocation: random number generator |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Final response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Tamayo‐Sarver 2004.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in STATA | |
| Data | Practicing Physicians with American College of Emergency Physicians membership | |
| Comparisons | 1. $2 bill 2. Lottery to win $250 |
|
| Outcomes | Response period not specified | |
| Topic | Health: diagnosis and treatment plan; practice environment | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Tambor 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians (US) | |
| Comparisons | 1. Continuing medical education credits 2. No credits | |
| Outcomes | Response period not specified | |
| Topic | Health: genetic knowledge, psychometric scales, demographics | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Tariq 2021.
| Study characteristics | ||
| Methods | Random allocation: random number generator in a secure database | |
| Data | 281 non‐responders to patient‐reported outcome survey, one year after orthopaedic surgery, US | |
| Comparisons | Personalised letter vs. standard letter | |
| Outcomes | Response 5 weeks after initial letter | |
| Topic | Health (one year postoperative surgical assessment) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Institutional Review Board‐approved letter that included personalised information on surgery site, date of surgery, surgeon picture, and scanned surgeon's signature, with a prepaid return envelope and the individual PROM form At tertiary multisite healthcare institution, validated PROMs are electronically collected on every elective knee, hip, and shoulder surgery in 9 hospitals and 59 orthopaedic surgeons utilising a prospective longitudinal cohort design. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator in a secure database |
| Allocation concealment? | Yes | Random allocation: random number generator in a secure database |
| Blinding of participants and personnel | Yes | Patients were blinded to which group they were in. Data collection and processing were done at a central processing site. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response 5 weeks after initial letter reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Taylor 1998.
| Study characteristics | ||
| Methods | Random allocation: stratified random sampling method | |
| Data | Young people in the Youth Cohort Study 8 sample, England | |
| Comparisons | 1. Preliminary notice letter 2. No preliminary notification | |
| Outcomes | Response within approximately 2 months | |
| Topic | Non‐health: attitudes and behaviour while transition from secondary school to labour market/tertiary education system | |
| Mode of Administration | Postal | |
| Notes | Mean age: 16.5 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Taylor 2006.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Participants registered in general practices in Aberdeen | |
| Comparisons | 1. Questionnaire printed in black ink 2. Questionnaire printed in green ink 3. Questionnaire sent in white envelope 4. Questionnaire sent in brown envelope |
|
| Outcomes | Response period within 6 months | |
| Topic | Health: screening questions for parkinsonism; EuroQol EQ‐5D | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Taylor 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 197 individuals aged 6 to 24 years with smartphones recruited via posters and internet postings to participate in a 5‐week study about mood and mobile game habits in return for receiving a $100 Amazon gift card at the end of the study | |
| Comparisons | Postal outcome diary vs. ePRO (iOS or Android app that displayed a web view with the daily diary form) vs. novel ePRO diary with in‐game rewards (Game‐Motivated ePRO ‐ including in‐game rewards when they completed a daily diary) | |
| Outcomes | Completion of daily diaries | |
| Topic | Non‐health (mood, mobile games, and the weather) | |
| Mode of Administration | Postal/electronic | |
| Notes | 6 daily multiple‐choice questions. The ePRO groups' app was a simple native iOS or Android app that displayed a web view with the daily diary form. The Game‐Motivated ePRO included the exact same web view and form. Therefore, the ePRO and Game‐Motivated ePRO groups had identical daily diaries; however, the Game‐Motivated ePRO participants received an in‐game reward (i.e. a pet) when they completed a daily diary, whereas the ePRO participants were just shown a screen thanking them for completing the diary and reminding them to return the next day. Participants in the Game‐Motivated ePRO group were informed that they did not need to play the game to fill out their daily diary. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | Participants were blind to which study group they were in until after completing the prestudy survey. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Completion of daily diaries reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Teisl 2005.
| Study characteristics | ||
| Methods | Random allocation: using random numbers generated in Excel | |
| Data | US residents | |
| Comparisons | 1. $1 cash 2. $2 cash 3. Phone card worth $2 4. Phone card worth $5 |
|
| Outcomes | Response period not specified | |
| Topic | Health: general perception of food and food processing, knowledge, and attitudes towards genetically modified foods | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Temple‐Smith 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General practitioners | |
| Comparisons | 1. Pre‐contact by GP researcher 2. Pre‐contact by non‐medical researcher (older woman) 3. Pre‐contact by non‐medical researcher (younger woman) 4. Pre‐contact by non‐medical researcher (younger man) | |
| Outcomes | Response within 8 weeks | |
| Topic | Health: kowledge, attitudes, behaviour, and practice (KABP) in relation to sexually transmitted diseases | |
| Mode of Administration | Postal | |
| Notes | Age: above 65 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Thistlethwaite 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | People aged 65 years and over from 7 counties in a midwestern state of the USA | |
| Comparisons | 1. No offer of results (NO); altruistic appeal (A); no demographic omission (no D) 2. NO; A; demographic omission (D) 3. NO; egoistic appeal (E); no D 4. NO; E; D 5. Offer of results (O); A; no D 6. O; A; D 7. O; E; no D 8. O; E; D | |
| Outcomes | Response within 4 weeks | |
| Topic | Non‐health: characteristics most desired in retirement centre, leisure‐time activities | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author; age: above 65 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Thomson 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Practising GPs in Lothian, Scotland | |
| Comparisons | 1. Lottery to win 6 bottles of champagne 2. Lottery to win 1 bottle of champagne |
|
| Outcomes | Response period not specified | |
| Topic | Health: GPs opinions on toenail surgery services offered by podiatrists and surgeons | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Tilbrook 2014.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants in the ATLAS treatment trial of acupuncture or Alexander training or usual care for the treatment of neck pain, due to receive a 6‐month follow‐up questionnaire, UK | |
| Comparisons | More personalised (Post‐it note with a handwritten message encouraging return of questionnaire) vs. less (control) | |
| Outcomes | Response after 3 reminders (42 days) | |
| Topic | Health (treatment of neck pain) | |
| Mode of Administration | Postal | |
| Notes | Northwick Park Neck Pain and associated Disability Questionnaire (NPQ) (1 page ‐ 10 questions). All participants sent a paper, postal, questionnaire. Those providing mobile numbers were sent a 7‐day SMS reminder. Postal reminder after 14 days, and again after a further 10 days. Final telephone follow‐up 7 days later. The intervention was: a yellow 3" ≤ square Post‐it note with handwritten text, in black ink with the wording 'Please complete and return to us as soon as possible. Thank you. [Signed with first name].' The intervention was only used on the first questionnaire sent out and was not used on any reminder questionnaires. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Yes | The response rate was determined by York Trials Unit data clerks who were not aware to which group the participants belonged. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders (42 days) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Tjerbo 2005.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Medical practitioners in Norway | |
| Comparisons | 1. Unconditional scratch lottery 2. Conditional lottery to win a holiday trip worth 8000 Norwegian Kroner 3. Control |
|
| Outcomes | — | |
| Topic | Health: relationship between primary care and secondary care | |
| Mode of Administration | Postal | |
| Notes | Language of publication Norwegian | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Todd 2015.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated random number generation | |
| Data | A sample of 2048 Australian women who had recently given birth at seven maternity units in New South Wales, Australia | |
| Comparisons | Choice to opt‐out from study vs. none | |
| Outcomes | Final response after 2 reminders | |
| Topic | Health (expectations and recent experiences of maternity care) | |
| Mode of Administration | Postal | |
| Notes | 123 questions; 20‐30 minutes completion time. Personalised pre‐notification letter, sponsored by an academic organisation, assurances of data confidentiality and anonymity, plus an SAE. 2 reminders | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated random number generation |
| Allocation concealment? | Yes | Random allocation: computer‐generated random number generation |
| Blinding of participants and personnel | Yes | A person not otherwise involved in the study co‐ordinated the mailout of pre‐notification letters, the survey packages and the reminder letters. This person had access to women's names and addresses but not their health or survey information. All completed surveys were received by the researchers, containing each woman's unique study number but no other identifying details. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Final response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Trussell 2004a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households in the designated market area in the US who agreed to participate in the mail survey during the screening telephone survey | |
| Comparisons | 1. No incentives 2. One $1 bill 3. Two $1 bills 4. Three $1 bills 5. Four $1 bills 6. Five $1 bills 7. Six $1 bills 8. Seven $1 bills 9. Eight $1 bills 10. Ten $1 bills |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: television viewing | |
| Mode of Administration | Postal | |
| Notes | Larger incentive: from one $1 bill to five $1 bills; smaller incentive: from six one $1 bills to ten $1 bills | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Trussell 2004b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households in the designated market area in the US who we were unable to contact during the screening telephone survey | |
| Comparisons | 1. No incentives 2. One $1 bill 3. Two $1 bills 4. Three $1 bills 5. Four $1 bills 6. Five $1 bills 7. Six $1 bills 8. Seven $1 bills 9. Eight $1 bills 10. Ten $1 bills |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: television viewing | |
| Mode of Administration | Postal | |
| Notes | Larger incentive: from one $1 bill to five $1 bills; smaller incentive: from six one $1 bills to ten $1 bills | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Trussell 2004c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households in the designated market area in the US who refused to participate in the mail survey during the screening telephone survey | |
| Comparisons | 1. No incentives 2. One $1 bill 3. Two $1 bills 4. Three $1 bills 5. Four $1 bills 6. Five $1 bills 7. Six $1 bills 8. Seven $1 bills 9. Eight $1 bills 10. Ten $1 bills |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: television viewing | |
| Mode of Administration | Postal | |
| Notes | Larger incentive: from one $1 bill to five $1 bills; smaller incentive: from six one $1 bills to ten $1 bills | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Tullar 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Large manufacturing firms | |
| Comparisons | 1. No follow‐up; no incentive 2. No follow‐up; 10 cents incentive 3. Follow‐up; no incentive 4. No follow‐up; 10 cents incentive | |
| Outcomes | Response within 8 weeks | |
| Topic | Non‐health: time for development of new product | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Tullar 2004.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Medicare recipients who underwent total hip replacement in 1995 | |
| Comparisons | 1. Handwritten addresses on the envelope of all outgoing mail 2. Computer‐printed addresses on the envelope of all outgoing mail 3. Hand‐stamped envelopes 4. Institutionally metered postage |
|
| Outcomes | Response period not specified | |
| Topic | Health: pain, functional status, satisfaction, complications, general health | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Turnbull 2015.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1850 eligible US intensive care physicians from an existing database, US | |
| Comparisons | Conditional non‐monetary incentive (Amazon gift card up to $50) vs. no incentive | |
| Outcomes | e‐login and e‐completion | |
| Topic | Health (communication about life support with families of critically ill patients) | |
| Mode of Administration | Web | |
| Notes | Web survey; 5‐minute completion time. Invitation by email containing a unique link to the survey. All invitations included the survey topic, number of questions, expected time required to complete the survey (5 minutes), IRB approval, study confidentiality, number of follow‐up/reminder emails for non‐responders, planned date for study closing Invitations for intensivists randomised to receive an incentive to participate also included the following text: "In appreciation for your participation, the first 100 respondents to complete the survey will be offered an Amazon.com gift code at the end of the survey. The code can be redeemed immediately for any amount up to $50. In selecting the compensation amount, please consider that this is a PhD thesis project being funded by a limited student budget." |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | e‐login and e‐completion reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Tuten 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Unemployed Croatians | |
| Comparisons | 1. No incentives 2. Offer of study results 3. Lottery of 1000 Kuna with immediate notification of the results 4. Lottery of 1000 Kuna with delayed (after 1 month) notification of the results |
|
| Outcomes | Response period not specified | |
| Topic | Health: psychosocial consequences of unemployment | |
| Mode of Administration | Electronic: online survey | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ulrich 2005.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Nurse practitioners and physician assistants practising in primary care in the US | |
| Comparisons | 1. No incentive 2. Unconditional $5 prepaid token incentive 3. Conditional lottery to win one of ten $100 prize draws |
|
| Outcomes | Response period not specified | |
| Topic | Health: ethical concerns in the course of practice | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Urban 1993.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians providing primary care | |
| Comparisons | 1. Return envelope with first‐class stamp 2. Business‐reply return envelope | |
| Outcomes | Response within 6 weeks | |
| Topic | Health: attitudes, beliefs, and practices regarding regular breast cancer screening | |
| Mode of Administration | Postal | |
| Notes | Age: 50‐75 years; mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
van den Berg 2011.
| Study characteristics | ||
| Methods | Quasi‐random allocation: sorting survivors alphabetically based on their address (first half was allocated to the mixed invitation group and the second half to the Web‐only invitation group) | |
| Data | 277 female survivors of childhood cancer | |
| Comparisons | Electronic vs choice (postal/electronic) | |
| Outcomes | Response after 6 weeks (2 reminders) | |
| Topic | Health (reproductive function, ovarian reserve, and risk of premature menopause in female childhood cancer survivors) | |
| Mode of Administration | Mixed | |
| Notes | An adaptation of a well‐tested questionnaire used by the Department of Epidemiology of the Netherlands Cancer Institute in a large‐scale Dutch cohort study on long‐term effects of ovarian stimulation for in vitro fertilisation. Participants in the mixed invitation group received an invitation that contained a paper‐based questionnaire together with an instruction sheet for the Web‐based questionnaire. This instruction sheet contained a personalised username, the name of the website, and a login code allowing them to log in to a secured part of the website and fill out the questionnaire. The envelope containing the study information package was sealed and put in another envelope together with a cover letter, signed by the head of the relevant paediatric oncology department, in which the study was explained very briefly. The paper‐ and Web‐based version of the questionnaire were identical in terms of the questions asked, their wording, and their order of presentation. In the Web‐based version, however, questions not relevant to the participant were automatically skipped. The Web‐based version of the questionnaire was accessible to participants through a website which was specially designed for the nationwide study. Participants in the Web‐only group received the instruction sheet containing the name of the website and the login details alone. If the questionnaire was not returned within 3 weeks, a reminder was sent by postal mail. For participants in the mixed invitation group, this reminder consisted of a letter in which the relevance of the study was again stressed and in which the individual was asked to respond. For participants in the Web‐only invitation group, a paper‐based version of the questionnaire was added to this reminder letter. When, after 3 weeks, no response was still received, patients in both groups were contacted by telephone and were asked to respond. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Quasi‐random allocation: alphabetical sorting |
| Allocation concealment? | No | Quasi‐random allocation: alphabetical sorting |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 6 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
van der Mark 2012.
| Study characteristics | ||
| Methods | Random allocation: computer random number generator | |
| Data | Parents of children at risk of developing asthma, participating in the ARCADE cohort, The Netherlands | |
| Comparisons | Conditional non‐monetary incentive (12.50 gift voucher) vs. no incentive Conditional non‐monetary incentive (daytrip to a popular amusement park) vs. no incentive | |
| Outcomes | Response after one reminder | |
| Topic | Health (quality of life and airway problems for children at high risk of asthma) | |
| Mode of Administration | Postal | |
| Notes | 130 multiple‐choice questions. Postal personalised letter and questionnaire consisting of a bright‐coloured cover and a stamped return envelope. The letter had a logo of the academic hospital and the specific ARCADE study logo, both in red ink and signed by the researcher. Postal reminders to non‐responders after 2 weeks. The follow‐up of the trial nested in the ARCADE study lasted for 2 years, maximum of 4 questionnaires (every 6 months; T0, T6, T12 and T18). T0 and T12: 130 multiple choice questions; T6 and T18: 38 multiple choice questions. Comparison of voucher extracted only (same control) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer random number generator |
| Allocation concealment? | Yes | Random allocation: computer random number generator |
| Blinding of participants and personnel | No | Research staff was not blinded to the randomisation during the follow‐up period. Neither participants nor personnel were blinded. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions (n = 0) reported |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Van Mol 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Full population of 15,651 higher education students of the University of Antwerp, Belgium | |
| Comparisons | Standard reminder email vs. standard reminder plus median response time to complete vs. standard reminder plus number of completed surveys vs. standard reminder plus median time and number completed | |
| Outcomes | Response after experimental reminder | |
| Topic | Non‐health (students' attitudes and opinions about internationalisation initiatives at the university) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. Available in Dutch and English. Students initially received an email with a link to the questionnaire. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after experimental reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
VanGeest 2001.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Physicians randomly selected from the American Medical Association's master file of all physicians practising in the US | |
| Comparisons | 1. $5 cash incentive 2. $10 cash incentive 3. $20 cash incentive | |
| Outcomes | Response period not specified | |
| Topic | Health: attitudes and responses in relation to utilisation and review pressure | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Veen 2015.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | University students, Germany | |
| Comparisons | Pre‐contact (mail pre‐notification to web survey) vs. none Non‐monetary incentive (EU 5 voucher ‐ conditional/unconditional) vs. no incentive Unconditional monetary incentive (EU 5 bill) (group 5) vs. no incentive (group 2) |
|
| Outcomes | First page only (e‐login) and all pages (e‐submissions; both after 2 reminders) | |
| Topic | Non‐health (study conditions, self‐rated competence, and student fraud) | |
| Mode of Administration | Web survey | |
| Notes | Questionnaire not described. The pre‐notification contained general information about the study. Students were informed that their university would be emailing a link to the survey shortly. To make the study appear more legitimate and to underscore its official character, logos of the university and the funding agency were placed in the footer. Non‐respondents and dropouts were sent up to two email reminders. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Veiga 1974.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Randomly selected managers | |
| Comparisons | 1. Stamped return envelope 2. Business‐reply return envelope 3. Internal mail return | |
| Outcomes | Response within 4 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Viera 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 8477 physicians randomly drawn from mailing lists of the American Academy of Family Physicians and the American College of Physicians | |
| Comparisons | Conditional non‐monetary incentive (2 hours of Continuing Medical Education (CME) credit) vs. no incentive | |
| Outcomes | Response after 2 reminders | |
| Topic | Health (physicians' opinions on "new ideas in cardiovascular disease prevention.") | |
| Mode of Administration | Web survey | |
| Notes | 40 items, approximately 10 mins to complete. Physicians were mailed a personalised letter describing the survey and a URL. Informed they would receive a chance to be entered into a draw for one of two $500 Visa gift cards if they completed the survey. Reminder letters to non‐responders sent at 2 and 4 weeks | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 2 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Virtanen 2007a.
| Study characteristics | ||
| Methods | Random allocation: using split‐panel design | |
| Data | Working‐age population living in rural areas in Finland | |
| Comparisons | 1. SMS reminder 2. Traditional postcard reminder |
|
| Outcomes | Response period within 28 days | |
| Topic | Non‐health: Information and Computer Technology (ICT) usage | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Virtanen 2007b.
| Study characteristics | ||
| Methods | Random allocation: using split‐panel design | |
| Data | Welfare and health professionals in Finland | |
| Comparisons | 1. SMS reminder 2. Traditional postcard reminder |
|
| Outcomes | Response period within 28 days | |
| Topic | Health: working and welfare conditions of health and social care workers | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Virtanen 2007c.
| Study characteristics | ||
| Methods | Random allocation: using split‐panel design | |
| Data | Members of trade union in Finland | |
| Comparisons | 1. SMS reminder 2. Traditional postcard reminder |
|
| Outcomes | Response period within 28 days | |
| Topic | Non‐health: employment | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Vocino 1977.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Members of the American Society for Public Administration | |
| Comparisons | 1. Metered envelope
2. Commemorative stamp
3. Deadline
4. No deadline
5. Cover letter by well‐known person in the discipline
6. Cover letter by unknown person in the discipline Factorial design |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Vogel 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals treated at an alcohol and drug treatment centre (Norway) | |
| Comparisons | 1. Short questionnaire; lottery ($70) incentive if respond
2. Short questionnaire; no lottery incentive
3. Long questionnaire; lottery ($70) incentive if respond
4. Long questionnaire; no lottery incentive Follow‐up after 7 months |
|
| Outcomes | Response period not specified | |
| Topic | Health: post‐discharge alcohol use, health status | |
| Mode of Administration | Postal | |
| Notes | Mean age: 42.4 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
VonRiesen 1979.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Veterinarians (Texas, US) | |
| Comparisons | 1. Postcard reminders 8 days after initial mailing 2. Second copy of questionnaire, with cover letter and business reply envelope, 8 days after initial mailing 3. No follow‐up | |
| Outcomes | Response period not specified | |
| Topic | Health: supplier configuration, reasons for patronage, dollar amounts of annual purchases | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Waisanen 1954.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Equal numbers of families owning and not owning television sets | |
| Comparisons | 1. Telephone pre‐contact 2. No telephone pre‐contact | |
| Outcomes | Response within 10 days | |
| Topic | Non‐health: self‐rating of personal possession, occupation, television, income, education | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Wakabayashi 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 6938 female nurses and/or midwives, who were aged at least 30 years, in the fifth‐wave follow‐up survey of the Japan Nurses' Health Study | |
| Comparisons | Stamped return envelopes vs. business‐reply return envelopes Study newsletter with first mailing vs. study newsletter with reminder | |
| Outcomes | First response and final response after 12 weeks (one reminder) | |
| Topic | Health (effects of lifestyle and healthcare practices on women's health) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. A thank‐you and reminder letter was mailed out to all respondents (regardless of whether they had already returned their questionnaires) after 6 weeks. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | First response and final response after 12 weeks (one reminder) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Walker 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | General population controls in a leg ulcer study aged 40‐99 years, randomly selected from the electoral roll, Auckland, New Zealand | |
| Comparisons | 1. Glossy brochure enclosed 2. No glossy brochure | |
| Outcomes | Response by post | |
| Topic | Health: SF‐36, HRQoL (leg ulcers) | |
| Mode of Administration | Postal | |
| Notes | Age: 40‐90 years | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Waltemyer 2005.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | National Collegiate Athletic Association (NCAA) Division I and III assistant softball coaches | |
| Comparisons | 1. Signed cover letter 2. Unsigned cover letter 3. White questionnaire 4. Yellow questionnaire |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wan 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1000 dermatologists from American Academy of Dermatology members who self‐identified as treating psoriasis and from active National Psoriasis Foundation members | |
| Comparisons | Higher unconditional monetary incentive ($10) vs. lower unconditional monetary incentive ($5) vs. no incentive | |
| Outcomes | Response after one reminder | |
| Topic | Health (preferences for psoriasis treatment) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire not described. Each participant to receive an initial questionnaire packet with either $5 or $10 (with a note offering this token of appreciation) or no cash. Postcard reminders and duplicate surveys sent to non‐respondents after the initial mailing | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ward 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Patients from a metropolitan general practice (Sydney, Australia) | |
| Comparisons | 1. $1 'scratchy' incentive with questionnaire
2. No incentive Follow‐up sent at 21 and 30 days |
|
| Outcomes | Response within 30 days | |
| Topic | Health: SF‐36, patient satisfaction, risk factors, chronic diseases | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Ward 1998.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Registered medical practitioners who had at least 1500 consultations per year | |
| Comparisons | 1. Exhaustive pre‐contact by telephone (continued until spoken to GP)
2. Gold pen incentive; University of NSW logo attached to questionnaire
3. Pre‐contact letter with University of NSW crests Follow‐up letter sent after 16 days to non‐respondents Second questionnaire sent after 23 days Telephone prompt from a non‐medical research assistant after 39 days |
|
| Outcomes | — | |
| Topic | Health: cancer screening, personal and family history of cancer, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | Mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Warriner 1996.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Households listed in the Grand River Watershed region of southwestern Ontario, Canada | |
| Comparisons | 1. Monetary incentive
2. No monetary incentive
3. Offer to make a charitable donation or lottery
4. No offer Factorial design |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: environmental issues | |
| Mode of Administration | Postal | |
| Notes | Author contacted: allocation was not concealed | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Warwick 2019.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated blocked randomisation scheme | |
| Data | 3,000 adults that had undergone an orthopaedic procedure within 2 years, and had an email address, at one institution in US | |
| Comparisons | No incentive vs. non‐monetary incentive (USD 5 donation to another patient in financial need, or to a research programme) vs. stress how survey response helps to improve care quality | |
| Outcomes | Response after 4 weeks (2 reminders) | |
| Topic | Health (postoperative patient‐reported outcome measures in an orthopaedic population) | |
| Mode of Administration | Web survey | |
| Notes | Surveys included questions on patient demographics as well as Patient‐Reported Outcomes Measurement Information System computer adaptive tests assessing physical function, pain interference, pain intensity, and depression. 5‐10 mins completion time. All patients received an email invitation with the same PROM survey link. Reminders containing the same text as in the original email were sent to non‐respondents at 1 and 2 weeks. Data collection ended 4 weeks after the initial email. (1) control: no incentive (n = 750); (2) patient donation: offer of a USD 5 donation to provide medical supplies to a paediatric orthopaedic patient (n = 751); (3) research donation: offer of a USD 5 donation to a procedure‐specific research programme (n = 749); or (4) explanation: explanation that response supports quality improvement (n = 750) |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated blocked randomisation scheme |
| Allocation concealment? | Yes | Random allocation: computer‐generated blocked randomisation scheme |
| Blinding of participants and personnel | Yes | Individuals were blinded to their participation in this study and were unaware that patients in the other experimental groups received different email messages. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 4 weeks (2 reminders) reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Weaver 2019.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 1224 physicians from the Minnesota Board of Medical Practice with both a postal and email address listed, US | |
| Comparisons | Postal with electronic follow‐up vs. electronic with postal follow‐up vs. postal only vs. electronic only | |
| Outcomes | Response after 3 reminders | |
| Topic | Health (factors that influence physicians' willingness to disclose medical errors and adverse events to patients and their families) | |
| Mode of Administration | Postal and electronic | |
| Notes | Questionnaire not described. Mail contacts included a cover letter that was printed on the University of Minnesota, Twin Cities letterhead. It was accompanied by a copy of their assigned survey booklet and a business‐reply envelope. For all web surveys, the body of the email included information that was similar to what was included in the mailed cover letters. The emails also included a URL to the survey. The mode experiment was embedded in the Medical Error Disclosure Survey (MEDS) and the Adverse Event Disclosure Survey (AEDS), which was fielded from November 2017 to February 2018. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Webborn 2022.
| Study characteristics | ||
| Methods | Random allocation: households randomly ordered in a table and a column repeating the numbers 1 to 12 sequentially was added to assign the test cells. | |
| Data | Smart Energy Research Laboratory (SERL) survey participants representative of seven regions in England and Wales | |
| Comparisons | Unconditional non‐monetary incentive (room thermometer) vs. conditional non‐monetary incentive (£5 Love2Shop voucher) vs. no incentive Push‐to‐web (enouraging Web response) vs. no push‐to‐Web Appeal stresses benefit to society (letter content version 1) vs. other (letter content version 2) | |
| Outcomes | Final response after 3 reminders | |
| Topic | Non‐health (household energy use) | |
| Mode of Administration | Web | |
| Notes | 10 minutes to complete. All mailings were sent in an A5 envelope with three project partner logos above the tagline 'University research for public good'. The clear panel on the envelope showed the address and 'Dear Sir/Madam' at the start of the invitation (or reminder) letter. The letter includes colour photos of the two professors conducting the study with scans of their signatures. Group 1's first mailing contained headlines relating to family/ future generations with the reasons for taking part followed by the 'call to action'. In contrast, group 2 received messaging about the UK becoming more energy efficient and the potential for energy bill savings. Control group was also offered postal participation in mailings 1 and 3 while the push‐to‐web treatment group was only sent the postal response forms in mailing 3. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | No | Random allocation: alternation |
| Allocation concealment? | No | Random allocation: alternation |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Final response after 3 reminders reported in full |
| Other sources of bias | No | Sequential randomisation |
Weilbacher 1952.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | University alumni members (Columbia, US) | |
| Comparisons | 1. Personalised letter of transmittal 2. Non‐personalised letter of transmittal | |
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Weir 1999.
| Study characteristics | ||
| Methods | Random allocation: computer algorithm | |
| Data | Patients with cerebrovascular disease discharged from hospital | |
| Comparisons | 1. Questionnaire sent via GP 2. Questionnaire sent direct to participants by research group | |
| Outcomes | — | |
| Topic | Health: stroke outcomes | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wells 1984.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | University undergraduates | |
| Comparisons | 1. University sponsor; business‐reply return envelope 2. University sponsor; no return postage 3. IRE sponsor; business‐reply return envelope 4. IRE sponsor; no return postage | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitude measure ‐ degree of satisfaction with the university's contribution to personal development | |
| Mode of Administration | Postal | |
| Notes | Mainly females | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Weltzien 1986.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals who had terminated from mental health treatment centres | |
| Comparisons | 1. 2 cents incentive with questionnaire 2. No incentive | |
| Outcomes | Response within 4 months | |
| Topic | Health: Consumer Satisfaction Questionnaire (CSQ) | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wenemark 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Parents of children with cancer, Stockholm, Sweden | |
| Comparisons | No incentive vs. conditional non‐monetary incentive (US $1.6 lottery ticket) vs. conditional non‐monetary incentive (US $1.6 lottery ticket plus an additional lottery ticket upon reply within 1 week) | |
| Outcomes | First response and final response after 3 reminders | |
| Topic | Health (stress in parents of children with cancer) | |
| Mode of Administration | Postal | |
| Notes | 5 pages; questions on background, and three scales assessing subjective perceptions of stress, burnout and strain Letter with the logo of the Children's Cancer Foundation of Sweden, questionnaire plus an SAE. Reminders sent after 1, 3 and 6 weeks |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | First response and final response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Wensing 1999a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adult patients who had visited a GP | |
| Comparisons | 1. Postal reminders
2. No reminders sent Reminder questionnaires sent at 3 weeks |
|
| Outcomes | — | |
| Topic | Health: Europep ‐ patients' evaluation of general practice care | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wensing 1999b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Adult patients who had visited a GP | |
| Comparisons | 1. Postal reminders
2. No reminders sent Reminder questionnaires sent at 3 weeks |
|
| Outcomes | — | |
| Topic | Health: Europep ‐ patients' evaluation of general practice care | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wensing 2005.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Elderly adults registered with 26 general practitioners in the Netherlands | |
| Comparisons | 1. Simple reminder card 2. Reminder + questionnaire 3. Reminder with request to explain non‐participation |
|
| Outcomes | Response period not specified | |
| Topic | Health: health problems, health information sought, and attendance of general practice | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Whitcomb 2004.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | High school students who did not apply to the Liberal Arts College | |
| Comparisons | 1. Email file format ‐ text 2. Email file format ‐ HTML 3. Background colour ‐ white 4. Background colour ‐ black 5. Graphical design (header) ‐ simple (institution name only) 6. Graphical design (header) ‐ complex (mimicked University homepage ‐ institutions name, campus photograph, quotation from the University president) |
|
| Outcomes | Response period not specified | |
| Topic | Non‐health: perception of the college, reason for not applying | |
| Mode of Administration | Electronic: Web‐survey | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
White 1997.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | A random sample of marriage and family therapists from a list of all approved supervisors of the American Association of Marriage and Family Therapy | |
| Comparisons | 1. Personalised cover letter; white questionnaire 2. Personalised cover letter; blue questionnaire 3. Generic cover letter; white questionnaire 4. Generic cover letter; blue questionnaire | |
| Outcomes | Response period not specified | |
| Topic | Health: demographics, Marriage and Family Therapist's supervision | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
White 2005a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Participants from the New Hampshire Women for Health (NHWH) study | |
| Comparisons | 1. Inclusion of a pen in the second mailing study 2. No pen in the second mailing study |
|
| Outcomes | Response period within 60 days | |
| Topic | Health: hormone replacement therapy, breast cancer, health‐related quality of life | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
White 2005b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Vanguard participants from the 13 counties of Western Washington State | |
| Comparisons | 1. Inclusion of a pencil in the second mailing study 2. No pencil in the second mailing study |
|
| Outcomes | Response period not specified | |
| Topic | Health: vitamins and lifestyle | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Whitehead 2011.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated (randomisation feature in Microsoft Excel 2007) | |
| Data | Sample of students (n = 1969) randomly selected from a database containing all students enrolled at a university, New Zealand | |
| Comparisons | Postal vs. electronic | |
| Outcomes | Response after 3 reminders | |
| Topic | Health (anxiety and depression in non‐psychiatric populations) | |
| Mode of Administration | Postal/electronic | |
| Notes | The questionnaire contained 41 items: the HADS (14 items), the SF‐12 v2 (12 items), a single fatigue item, and the Fatigue Symptom Inventory (FSI) (14 items). The mail group were sent a letter of introduction and the questionnaire to their home address. A stamped, self‐addressed envelope was included. 2 reminders at weeks 2 and 4. The online group was emailed an invitation to participate with a web link. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated (randomisation feature in Microsoft Excel 2007) |
| Allocation concealment? | Yes | Random allocation: computer‐generated (randomisation feature in Microsoft Excel 2007) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Whiteman 2003.
| Study characteristics | ||
| Methods | Random allocation: computerised random number generation | |
| Data | Women in the Baltimore Metropolitan area who reported their history of hot flashes | |
| Comparisons | 1. Introductory postcard mailed 1 week before the questionnaire 2. Scratch‐off lottery ticket worth $1.00 3. $1 bill 4. No incentives |
|
| Outcomes | Response period within 95 days | |
| Topic | Health: risk of hot flashes in midlife women, pregnancy history, hormonal contraceptive use, menstrual history | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Yes | A ‐ adequate |
Whiteside 2019.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated allocation sequence (using STATA) | |
| Data | 1862 community dwelling, older adults at elevated risk of falling (eligible for the OTIS trial) | |
| Comparisons | Pen vs. no pen | |
| Outcomes | Return of questionnaire (consent form) | |
| Topic | Health (risk of falling) | |
| Mode of Administration | Postal | |
| Notes | Questionnaire (consent form) not described. Invitation letter, a participant information sheet, consent form, screening form, and a pre‐paid return envelope. Participants allocated to the intervention group of this embedded trial also received a York Trials Unit branded pen in their invitation pack. The control participants did not receive a pen in their invitation pack. Recipients of an invitation pack were asked to return a completed consent form and screening form if they were willing to take part in the OTIS trial. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: computer‐generated allocation sequence (using STATA) |
| Allocation concealment? | Unclear | Random allocation: computer‐generated allocation sequence (using STATA) |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Whitmore 1976.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals who had purchased a new car | |
| Comparisons | 1. Key ring incentive with questionnaire
2. No incentive Follow‐up sent at 2 weeks |
|
| Outcomes | — | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wiant 2018.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Medical oncologists drawn from the American Medical Association Physician Masterfile who had treated cancer patients within the previous 12 months | |
| Comparisons | Unconditional non‐monetary incentive ($50 cheque) vs. conditional non‐monetary incentive ($50 cheque) | |
| Outcomes | First response and response after 2 reminders and a phone call | |
| Topic | Health (experiences, attitudes, and recommendations concerning genomic testing in oncology) | |
| Mode of Administration | Postal | |
| Notes | 12 pages. Personalised cover letter, an endorsement letter from the American Society of Clinical Oncology, a pen with the study's name printed on it, questionnaire booklet, and a business reply envelope | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | First response and response after 2 reminders and a phone call reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Willits 1995.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Residents of Pennsylvania (US) | |
| Comparisons | 1. No preamble; general question first
2. No preamble; general question last
3. Preamble; general first
4. Preamble; general last Follow‐up sent to non‐respondents (postcard and 2 additional mailings including another copy of the questionnaire) |
|
| Outcomes | — | |
| Topic | Health: quality of life (QoL) in rural areas, QoL in relation to community spirit, healthcare services, recreational opportunities, job opportunities, air quality | |
| Mode of Administration | Postal | |
| Notes | Mean age: 42.6 years; mainly males | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wilson 2010.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | 536 UK‐based principal investigators of health services and public health research completed during 2003‐2008 | |
| Comparisons | 'Knowledge of' vs. 'no knowledge of' a conditional £10 Amazon gift voucher | |
| Outcomes | Response after 5 reminders | |
| Topic | Non‐health (practices of intramural MRC Research Units) | |
| Mode of Administration | Web survey | |
| Notes | 36 questions that could be completed in 20‐30 minutes. Participants were contacted by email and invited to complete an online questionnaire via URL. Four reminder emails sent out to non‐respondents (one, two, three, and four weeks), with a fifth postal reminder The email sent to the participants in the 'knowledge' group stated that those who completed the online questionnaire would receive a £10 Amazon gift voucher. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Windsor 1992.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | Individuals listed on electoral registers | |
| Comparisons | 1. Questionnaire included questions on ethnic origin and housing tenure
2. Questionnaire included question on housing tenure only
3. Questionnaire included question on ethnic origin only
4. Neither question included 2 reminders sent |
|
| Outcomes | Response period not specified | |
| Topic | Health: health and hospital survey ‐ health and hospital attendance, consultation with GPs, demographics, housing tenure | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wiseman 1972.
| Study characteristics | ||
| Methods | Random allocation: systematic allocation | |
| Data | Residents of a suburban Boston community, USA | |
| Comparisons | 1. Telephone pre‐notification ‐ mail survey 2. No pre‐notification ‐ mail survey | |
| Outcomes | Response period not specified | |
| Topic | Health: birth control devices, legalising abortions, lowering the legal drinking age Non‐health: Giving state aid to Catholic schools |
|
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wiseman 1973.
| Study characteristics | ||
| Methods | Random allocation: systematic allocation | |
| Data | Residents in statewide telephone listings, Massachusetts, USA | |
| Comparisons | 1. 10 cent incentive (MI); postcard follow‐up 3 days after initial mailing (FU); business reply envelope (BRE); offer of survey results (OR) 2. MI; no follow‐up (no FU); BRE; OR 3. MI; FU; BRE; no offer of survey results (no OR) 4. MI; no FU; BRE; no OR 5. MI; FU; stamped return envelope (SRE); OR 6. MI; no FU; SRE; OR 7. MI; FU; SRE; no OR 8. MI; no FU; SRE; no OR 9. No monetary incentive (NI); FU; BRE; OR 10. NI; no FU; BRE; OR 11. NI; FU; BRE; no OR 12. NI; no FU; BRE; no OR 13. NI; FU; SRE; OR 14. NI; no FU; SRE; OR 15. NI; FU; SRE; no OR 16. NI; no FU; SRE; no OR | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: attitudes and opinions about Massachusetts state lottery | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wong 2021.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Adult patients discharged from the Royal Adelaide Hospital intensive care unit (ICU) between June 2018 and April 2019 who had spent at least 48 h in the ICU and who were still alive at the time of the follow‐up study. | |
| Comparisons | Postal vs. mixed‐mode, (online with paper follow‐up) | |
| Outcomes | First response and response after reminders | |
| Topic | Health (QoL, anxiety and depression) | |
| Mode of Administration | Postal/electronic | |
| Notes | EuroQoL‐5D‐5L, Hospital Anxiety and Depression Scale (HADS), and Impact of Event Scale‐Revised (IES‐R). Patients were emailed a website link to the survey; patients without email received a letter with a simple website address and a unique login. Email users were sent automated reminder emails after 3, 6, and 9 days. Forced responses were used in the online survey, requiring each question to be answered to progress. The online survey question order and wording were identical to that of the paper modality. In the paper group, patients received a paper survey with a postage‐paid reply envelope. In both groups, patients who had not completed their survey received a reminder paper survey after 14 days and a reminder phone call to return their received survey after 21 days. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | No | Patients were blinded to their group allocation; however, clinicians and researchers were not. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | First response and response after reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Woodward 1985.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Household members (South Australia) | |
| Comparisons | 1. Cover letter included offer of chance to win free dinner
2. Cover letter did not include offer Follow‐up at 1, 3 and 7 weeks |
|
| Outcomes | Response within 10 weeks | |
| Topic | Health: respiratory history of the youngest child | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Woolf 2021.
| Study characteristics | ||
| Methods | Random allocation: random number generator on a Casio calculator | |
| Data | Study corresponding authors included in a systematic review, whose studies were at unclear risk of bias | |
| Comparisons | Pre‐notification email vs. no pre‐notification | |
| Outcomes | Response after 4 weeks | |
| Topic | Non‐health (information on study design of an RCT) | |
| Mode of Administration | Electronic | |
| Notes | Questionnaire not described. All authors were emailed the questionnaire 1 day after the pre‐notification email was sent. Follow‐up contacts were sent at one and two weeks after the initial sending of the questionnaire, where a response had not been received. Other than the pre‐notification, all communication to the two arms were sent on the same day. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: random number generator on a Casio calculator |
| Allocation concealment? | Yes | Random allocation: random number generator on a Casio calculator |
| Blinding of participants and personnel | Yes | No active blinding of participants or personnel occurred. However, no material risk of bias should have been introduced. Because participants were unaware of having been randomised, any effect of treatment could not be because of knowing that they had been specially selected for an intervention which others had not received. Although the participant still knew they had received the pre‐notification, this knowledge is part of the effect of a pre‐notification. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 4 weeks reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Worthen 1985a.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | School teachers listed on the Education Association Membership roster (Utah, US) | |
| Comparisons | 1. Personalised cover letter 2. Form cover letter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: Classroom teachers' opinion about what should be taught on an educational measurement course | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Worthen 1985b.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | School teachers listed on the Education Association Membership roster (Utah, US) who did not respond to an earlier questionnaire with a personalised letter | |
| Comparisons | 1. Personalised cover letter 2. Form cover letter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: Classroom teachers' opinion about what should be taught on an educational measurement course | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Worthen 1985c.
| Study characteristics | ||
| Methods | Random allocation: method not specified | |
| Data | School teachers listed on the Education Association Membership roster (Utah, US) who did not respond to an earlier questionnaire with a standard form letter | |
| Comparisons | 1. Personalised cover letter 2. Form cover letter | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: Classroom teachers' opinion about what should be taught on an educational measurement course | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wotruba 1966.
| Study characteristics | ||
| Methods | Random allocation: systematic division of a random sample | |
| Data | Urban household residents | |
| Comparisons | 1. 25 cents sent with questionnaire 2. 50 cents promised on return of questionnaire 3. No incentive | |
| Outcomes | Response within 6 weeks | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Wright 1984.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | People listed in the latest telephone directories, New Zealand 1983 | |
| Comparisons | 1. Personal salutation (P); black and white letterhead (BW); white outward envelope (Wh); $100 cash lottery incentive (Ca) 2. P; BW; Wh; garden voucher lottery incentive (Ga) 3. P; BW; brown outward envelope (Br); Ca 4. P; BW; Br; Ga 5. P; coloured letterhead (Co); Wh; Ca 6. P; Co; Wh; Ga 7. P; Co; Br; Ca 8. P; Co; Br; Ga 9. Impersonal salutation (IP); BW; Wh; Ca 10. IP; BW; Wh; Ga 11. IP; BW; Br; Ca 12. IP; BW; Br; Ga 13. IP; Co; Wh; Ca 14. IP; Co; Wh; Ga 15. IP; Co; Br; Ca 16. IP; Co; Br; Ga | |
| Outcomes | Response period not specified | |
| Topic | Non‐health: motivation of gardeners and users of garden products, sociodemographics | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Wright 1995.
| Study characteristics | ||
| Methods | Random allocation: systematic sample from list ordered alphabetically | |
| Data | New Zealand councillors who had participated in another survey 18 months previously | |
| Comparisons | 1. Pre‐notification letter sent 2 weeks prior to questionnaire mailing 2. No pre‐contact | |
| Outcomes | Response after 2 follow‐up reminders | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
Wunder 1988.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Subscribers to a large health maintenance organisation in a major metropolitan area in the Midwestern United States | |
| Comparisons | 1. Hand‐addressed envelope 2. Computer‐generated address on envelope | |
| Outcomes | Response period not specified | |
| Topic | Health: satisfaction benefit package, characteristics of subscribers | |
| Mode of Administration | Postal | |
| Notes | Method of allocation ascertained through contact with author | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Wynn 1985.
| Study characteristics | ||
| Methods | Random allocation: alternation | |
| Data | Members, past and present, of an exercise and recreational club in a medium‐sized southwestern city (US) | |
| Comparisons | 1. No pre‐contact by telephone 2. Telephone pre‐contact asking permission to send questionnaire (foot‐in‐the‐door manipulation) 3. Telephone pre‐contact asking questions (probe‐foot‐in‐the‐door manipulation) | |
| Outcomes | Response period not specified | |
| Topic | Health: planning of a possible expansion effort for an exercise recreational club | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | No | C ‐ inadequate |
Xie 2013.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Nurses selected from the Association of Hong Kong Nursing Staff (AHKNS) | |
| Comparisons | Pre‐notification vs. no prenotification | |
| Outcomes | Response after one reminder | |
| Topic | Health (demographics, work status, lifestyle factors, reproductive information, and dietary habits) | |
| Mode of Administration | Postal | |
| Notes | 153 items printed on a 4‐page, double‐sided booklet. The cover page provided a brief introduction to the study. An informed consent form was also attached. Two rounds of mailing were conducted. In the first round of mailing, nurses in the direct questionnaire mailing group received the questionnaire with a prepaid return envelope, whereas those in the pre‐notification group received a pre‐notification package that included an introduction leaflet with a reply slip, and a prepaid return envelope. After 3 weeks, the second round of mailing was conducted. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Yes | The investigators and participants remained unaware about the group allocation. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Yetter 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | School psychologists with an email address, US | |
| Comparisons | Shorter vs. longer Electronic vs. postal | |
| Outcomes | Response after 2 reminders | |
| Topic | Non‐health (perceptions of pre‐referral intervention teams for addressing children's school‐related academic and behaviour difficulties) | |
| Mode of Administration | Electronic vs. postal | |
| Notes | Shorter (20 items), longer (66 items). Postal pre‐notifications were sent first. Then survey packets (for the paper survey participants) and emails (for Web participants) containing a URL were sent, followed by 2 reminders to participate. The online survey was made to look as similar as possible to the printed version. It appeared in black and white only, and the radio buttons were presented in click format. The participants were able to navigate forward and backward through the survey instrument by clicking on next and back arrow at the bottom of each screen. On completing the questionnaire, the participants were presented with a 'Success' Web page. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | Yes | Exclusions reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Young 2015.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | GPs in New South Wales (NSW) and Victoria, Australia | |
| Comparisons | Unconditional non‐monetary incentive vs. conditional non‐monetary incentive vs. no‐incentive | |
| Outcomes | Response after 3 reminders | |
| Topic | Health (cancer care) | |
| Mode of Administration | Web | |
| Notes | Questionnaire not described. GPs were mailed an advance letter approximately 1 week before the main letter of invitation. Up to 3 mailed reminder letters were sent to non‐responders at biweekly intervals. The incentive was a book voucher ($75 in NSW and $50 in Victoria) | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Response after 3 reminders reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Young 2020.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Participants in a cohort from a host trial of screening for lung cancer | |
| Comparisons | Unconditional £5 multi‐store paper gift voucher vs. conditional £5 multi‐store paper gift voucher | |
| Outcomes | Response after 5 weeks (2 telephone reminders and one postal reminder) | |
| Topic | Health (cancer, depression) | |
| Mode of Administration | Postal | |
| Notes | 16 pages long and included the Hospital Anxiety and Depression Scale, Positive and Negative Affect Schedule, Illness Perceptions Questionnaire, Cancer Worry Scale, and measures of health status, health anxiety, perceived risk of lung cancer and tobacco use. A4 sized questionnaire sent folded in half and had participants' initials and unique study ID numbers handwritten on the front. Envelopes were sent with second‐class postage stamps, printed address labels, and a prepaid second‐class return envelope enclosed. One week after the first questionnaire was mailed, a telephone call was made to check receipt of the questionnaire, answer any questions, and encourage its return by emphasising the importance of the research. If telephone contact was not made after two attempts, a brief scripted voicemail was left where possible. If a questionnaire was not returned 2 weeks after mailing, an identical reminder copy was sent with another prepaid envelope. If the questionnaire was not returned 3 weeks after mailing, a reminder telephone call was attempted. Two call attempts were made and, if unsuccessful, a voicemail was left where possible. Questionnaires had a £5 multi‐store paper gift voucher attached to the front with a paper clip. Questionnaires were sent at 3, 6, and 12 months after baseline and responses recorded at each time point. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not specified. Participants were not blinded. |
| Blinding of outcome assessment | Yes | No outcomes assessed (response only) |
| Incomplete outcome data | Yes | Exclusions were reported. |
| Selective reporting | Yes | Outcomes at all time points reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Yu 2017.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 35,421 non‐respondents to the 4th wave survey of participants in the World Trade Centre Health Registry | |
| Comparisons | Conditional $10 cash incentive vs. no incentive | |
| Outcomes | Final response after 10 email reminders with survey links, and 4 postcard reminders | |
| Topic | Health (long‐term health impact of the September 11, 2001 (9/11) terrorist attacks in New York City) | |
| Mode of Administration | Postal/electronic | |
| Notes | During the incentive experiment period, reminder phone calls and door‐to‐door outreach were also conducted concurrently, in addition to email and postcard reminders that were sent frequently throughout the data collection period. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcome assessment used (counts of responses only) |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ziegenfuss 2010.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 770 randomly selected Olmsted County residents aged 25‐65 years | |
| Comparisons | Postal vs. choice (postal/Web) | |
| Outcomes | Response after one reminder | |
| Topic | Health (bowel disease) | |
| Mode of Administration | Mixed | |
| Notes | 16 pages. The survey packets were equivalent except for a Web address and personal identification number in the cover letter for the Internet option. All individuals received a topically related book as an incentive. A reminder letter was mailed to non‐responders 3 weeks after the initial mailing. | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | Yes | Exclusions were not reported. |
| Selective reporting | Yes | Response after one reminder reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ziegenfuss 2011.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | Individuals known to have diabetes mellitus in the Mayo Health System | |
| Comparisons | Offer of survey results as incentive vs. none | |
| Outcomes | Final response after one reminder | |
| Topic | Health (diabetes care delivery in the primary‐care setting) | |
| Mode of Administration | Postal | |
| Notes | 5‐page booklet. The package contained a cover letter signed by the study principal investigator and a local diabetes physician champion. Non‐respondents were sent a second letter and questionnaire 4 weeks after the first mailing. The cover letter sent to those in the intervention arm included an additional paragraph that stated that as a 'token of appreciation', the respondent would have the opportunity to indicate in the last question of the survey whether they wanted a summary of the results sent to them after they completed the survey. |
|
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions not reported |
| Selective reporting | Yes | Outcomes reported in full |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ziegenfuss 2012.
| Study characteristics | ||
| Methods | Random allocation: method unspecified | |
| Data | 2000 practising US physicians selected from the AMA Physician Masterfile who had not responded to the first wave of a survey | |
| Comparisons | Envelope with a brightly coloured sticker reading "$25 incentive" vs. no envelope sticker | |
| Outcomes | Response period not specified | |
| Topic | Health (moral beliefs and views on controversial healthcare topics) | |
| Mode of Administration | Postal | |
| Notes | 8‐page questionnaire. Package not described | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Unclear | Random allocation: method unspecified |
| Allocation concealment? | Unclear | Random allocation: method unspecified |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | No | Response period not specified |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Ziegenfuss 2014.
| Study characteristics | ||
| Methods | Random allocation: computer‐generated | |
| Data | Practising registered nurses and physicians in Minnesota, US | |
| Comparisons | Padded envelope vs. priority mail envelope | |
| Outcomes | First response | |
| Topic | Health (practices and perspectives on H1N1 pandemic influenza vaccination) | |
| Mode of Administration | Postal | |
| Notes | 7 pages. Cover letter, an endorsement letter from the Minnesota Department of Health, a postage‐paid return envelope, and a laser pointer pen as a thank‐you gift | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Sequence generation | Yes | Random allocation: computer‐generated |
| Allocation concealment? | Yes | Random allocation: computer‐generated |
| Blinding of participants and personnel | Unclear | Blinding of personnel not described. Participants were not blinded to intervention. |
| Blinding of outcome assessment | Yes | No outcomes were assessed (counts of responses only). |
| Incomplete outcome data | No | Exclusions were not reported. |
| Selective reporting | No | Only outcomes after initial mailing reported |
| Other sources of bias | Yes | No grounds for concern about other sources of bias from reading the study report |
Zusman 1987.
| Study characteristics | ||
| Methods | Random allocation: on the basis of study identification number and done without reference to subject characteristics | |
| Data | Undergraduate transfer students | |
| Comparisons | 1. $1 incentive sent with first mailing
2. No incentive sent Follow‐up of non‐respondents several weeks after first mailing |
|
| Outcomes | Response period not specified | |
| Topic | Not specified | |
| Mode of Administration | Postal | |
| Notes | — | |
| Risk of bias | ||
| Item | Authors' judgement | Support for judgement |
| Allocation concealment? | Unclear | B ‐ unclear |
DNA: Deoxyribonucleic acid
EQ‐5D: EuroQol‐ 5 Dimension
GP: General practice
NHS: National Health Service
SAE: Self‐addressed envelope
SWAT: Study within a Trial
SF‐12: 12‐Item Short Form Survey
SF‐36: 36‐Item Short Form Health Survey
SMS: Short Message Service
Characteristics of excluded studies [ordered by study ID]
| Study | Reason for exclusion |
|---|---|
| Alcaraz 2020 | Not postal questionnaire |
| Alexander 2008a | Not postal questionnaire |
| Allen 1980 | The comparison in this study is biased by the fact that people in the pre‐notification group were given the choice of whether to receive the questionnaire or not whereas people in the no pre‐notification group were not given this choice. |
| Anderson 1975 | It was not possible to determine whether this study was randomised. |
| Anderson 2007 | Not a randomised trial |
| Angus 2003 | Not a randomised controlled trial |
| Antoun 2020 | Not postal questionnaire |
| Armstrong 1975 | Review article |
| Asch 1994 | The comparison in this study was confounded ‐ the author, with reference to the several differences between the 2 mailing strategies, stated 'We cannot determine which of these differences underlies our results.' |
| Ash 1952 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Baron 2001 | The comparison in this study was confounded by the colour of the questionnaire. |
| Beaty 2018 | Not a randomised trial |
| Becker 2019 | Not a randomised trial |
| Beebe 2011 | Not postal questionnaire |
| Berthelot 1993 | Not a randomised trial |
| Bevis 1948 | It was not possible to determine whether this study was randomised. |
| Beynon 2010 | Not postal questionnaire |
| Biggar 1992 | All comparisons in the study were confounded. |
| Blumberg 1974 | It was not possible to determine whether this study was randomised and the data which would be needed were only referred to, not presented. Attempts to contact the author have been unsuccessful. |
| Blumenfeld 1973 | It was not going to be possible to determine whether this study was randomised as the author had died. |
| Boucher 2015 | Not a randomised trial |
| Brealey 2007 | Not a randomised trial |
| Brechner 1976 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Breeman 2013 | Not a randomised trial |
| Brennan 1958 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Brennan 1990 | The comparison in this study was confounded. |
| Burkhart 2021 | Not a randomised trial |
| Cadilhac 2012 | Not postal questionnaire |
| Callegaro 2010 | Not postal questionnaire |
| Cartwright 1968 | The comparison of different lengths was confounded by other differences between the two questionnaires. |
| Cartwright 1989 | It was not possible to determine whether this study was randomised. Contact details of the author were unavailable. |
| Cernat 2018 | Not postal questionnaire |
| Champion 1969 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Chen 2016 | Not a randomised trial |
| Cheung 2019 | Not postal questionnaire |
| Childs 2005 | The study did not calculate the response for the different order of administration of the questionnaires. |
| Chin 2015 | Not postal questionnaire |
| Choi 2017 | Not a randomised trial |
| Chyou 2017 | Not a randomised trial |
| Clark 2008 | Not postal questionnaire |
| Coleman 2021 | Not postal questionnaire |
| Coleman 2021a | Not postal questionnaire |
| Conrad 2007 | Not postal questionnaire |
| Cook 1985 | Incentive only given after agreement to participate in a further study, not just for returning the questionnaire. |
| Dal Grande 2016 | Not postal questionnaire |
| Desborough 2008 | Not postal questionnaire |
| Dillman 1972 | No useful experimental data presented |
| Down 2010 | Not a randomised trial |
| Drake 2014 | Not a randomised trial |
| Drummond 2015 | Confounded by different incentive amounts and whether they were offered on conditional or unconditional basis (unconditional scratch card (with potential to win EURO 5000) vs. conditional lottery for one of three high street shopping vouchers worth EURO 300). |
| Duan 2007 | Not postal questionnaire |
| Duncan 2019 | Not a randomised trial |
| Dunlap 1950 | It was not possible to determine whether this study was testing return rate of a questionnaire. Attempts to contact the author have been unsuccessful. |
| Eaton 2020 | Not postal questionnaire |
| Ebert 2018 | Not a randomised trial |
| Egeland 2017 | Confounded trial ‐ cannot separate the effect of the modifed cover letter from the effects of the name of the patient handwritten at the top and with the handwritten signature of the surgeon |
| Eisinger 1974 | It was not possible to determine whether this study was randomised. Attempts to contact authors have been unsuccessful. |
| Elinson 1950 | There were insufficient data presented in this paper to include it. It has also not been possible to determine whether the questionnaire in the experiment was postal. Attempts to contact authors have been unsuccessful. |
| Ettridge 2021 | Not postal questionnaire |
| Everett 1997 | The comparison in this study was confounded by the colour of the questionnaire. |
| Fang 2006 | This study did not calculate the response but inspected the correlation between the material incentive and the participants' characteristics. |
| Fang 2012 | Not postal questionnaire |
| Fang 2021 | Not a randomised trial |
| Fernandez Lynch 2019 | Not postal questionnaire |
| Ferriss 1951 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Fleming 2013 | Not postal questionnaire |
| Fu 2013 | Not postal questionnaire |
| Furse 1981 | Authors could not remember whether the study was randomised. |
| Gerace 1995 | This study examined response rates of a postal request for more information, not a questionnaire. |
| Gibson 2020 | Not postal questionnaire |
| Gillespie 1975 | The comparison in this study was confounded. |
| Gooden 2021 | Confounded trial |
| Groves 2011 | Not postal questionnaire |
| Hansen 2004 | Not a randomised controlled trial |
| Hare 1998 | The comparison in this study was confounded by the colour of the questionnaire. |
| Harlow 1993 | Examined response rates to telephone interviews not postal questionnaires |
| Harrison 2019 | Not a randomised trial |
| Haugejorden 1987 | Randomised controlled trial but not of methods to increase response to postal questionnaires |
| Hawes 1987 | Author no longer has original data to be able to provide confirmation of numbers of questionnaires administered and returned. |
| Heads 1966 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Heje 2006 | The primary questionnaire was delivered personally to the patient either at the surgery or at home. |
| Helgeson 2002 | Author no longer has original data to be able to provide confirmation of numbers of questionnaires administered and returned. |
| Hennrich 2021 | Not postal questionnaire |
| Hing 2005 | Not a postal questionnaire |
| Hinrichs 1975 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Hocking 2006 | Not postal questionnaire |
| Horevoorts 2015 | Not a randomised trial |
| Hsu 2017 | Not postal questionnaire |
| Hughes 1989 | Author was contacted: the study records have been discarded. |
| Hurd 2017 | Not a randomised trial |
| Hurd 2019 | Not a randomised trial |
| ISRCTN16437731 2016 | Trial protocol |
| Ives 1990 | Author was contacted: confirmed that participants were not randomly allocated. |
| Jacobson 2016 | Not postal questionnaire |
| Jiang 2005 | Not a randomised controlled trial |
| Jobber 2004 | Not a randomised trial |
| Johnson 2014 | Not postal questionnaire |
| Johnson 2015 | Not a randomised trial |
| Kato 2021 | Not a randomised trial |
| Kerin 1974 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Kerin 1977 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Kerin 1983 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Kimball 1961 | It was not possible to confirm that this study was randomised. Attempts to contact the author have been unsuccessful. |
| Kimel 2010 | Not postal questionnaire |
| Koetsenruijter 2015 | Not postal questionnaire |
| Kundig 2011 | Not postal questionnaire |
| Labovitz 2017 | Not postal questionnaire |
| Lane 2011 | Not a randomised trial |
| Lane 2017 | Not a randomised trial |
| Lapane 2007 | Not postal questionnaire |
| Larsson 1970 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Lavender 2009 | Not postal questionnaire |
| Leece 2004a | Not a randomised trial |
| Li 2015 | Confounded trial (Table 1 shows that experimental conditions varied by timing of delivery) |
| Lim 2020 | Not postal questionnaire |
| Liu 2011 | Confounded trial; size of incentive was confounded by type of incentive. |
| Longworth 1953 | Author drew six different samples, and tested a different type of intervention on each without a comparison group. |
| Lopez‐ Cano 2007 | Not a randomised controlled trial |
| Lund 1988 | Comparisons of questionnaires which were mailed were confounded. |
| Malhotra 2008 | Not postal questionnaire |
| Maloshonok 2016 | Not postal questionnaire |
| Marks 1981 | Author could not remember whether the study was randomised. |
| May 1960 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| McCree‐Hale 2010 | Not a randomised trial |
| McDermott 2003 | Incentives were the same for all the three questionnaires. |
| McDermott 2018 | Not postal questionnaire |
| Mehta 1995 | Two groups received postal questionnaires, but one group received a combination of methods (monetary incentive, pre‐notification and follow‐up). Comparisons for combinations of methods have not been created in this review. |
| Millar 2021 | Not postal questionnaire |
| Murdoch 2010 | Not postal questionnaire |
| Myers 2007 | Confounded trial of university sponsorship (the ‘industry group’ received a cover letter containing logos of both the university and the industry sponsor). |
| Neve 2021 | Not a randomised trial |
| Nitecki 1975 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Nitikman 2015 | Not a randomised trial |
| Nitikman 2017 | Not postal questionnaire |
| Nord 2007 | Not postal questionnaire |
| O'Toole 2008 | Not postal questionnaire |
| Oden 1999 | The comparison in this study was confounded by the colour of the questionnaire. |
| Onoye 2012 | Not a randomised trial |
| Otzen 2020 | Not a randomised trial |
| Palmer 2018 | Not a randomised trial |
| Pariyo 2019 | Not postal questionnaire |
| Perneger 2003 | The intervention did not include strategies to increase response to a postal or electronic questionnaire. |
| Perneger 2014 | Not a randomised trial |
| Peytremann‐Bridevaux 2006a | The intervention did not include strategies to increase response to a postal or electronic questionnaire. |
| Pieper 2018 | Not postal questionnaire |
| Porter 2004 | The data presented in this paper were the same as those presented in an earlier paper, Porter 2003. |
| Pottick 1991 | This study examined postal methods to improve response to a face‐to‐face survey. |
| Prado 2012 | Not a randomised trial |
| Rafiq 2016 | Not postal questionnaire |
| Rashidian 2008 | Not a randomised trial |
| Richards 2009 | Not postal questionnaire |
| Richards 2010 | Not a randomised trial |
| Robbins 2018 | Not postal questionnaire |
| Robin 1973 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Robin 1976 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Rocheleau 2012 | Not postal questionnaire |
| Roeher 1963 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Rudd 1980 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Ryan 2018 | Not postal questionnaire |
| Salomone 1978 | The number of people allocated to each experimental group was not presented and attempts to obtain this information from the authors have been unsuccessful. |
| Senf 1987 | Option to refuse postcards were sent to half of all participants prior to sending questionnaire. However, response rates to questionnaires could not be compared because questionnaires were returned anonymously. |
| Shackleton 1982 | The data presented in this paper were the same as those presented in an earlier paper by Shackleton (1980). |
| Shah 2016 | Not postal questionnaire |
| Shermis 1982 | Comparisons of questionnaires which were mailed were confounded. |
| Sheth 1975 | The data presented in this paper were from the same study as those presented in an included study by Roscoe and Sheth (1975). |
| Shin 2015 | Not postal questionnaire |
| Short 2015 | Not a randomised trial |
| Simcoe 2015 | Not a randomised trial |
| Sirken 1960 | Could not confirm random allocation. Author contacted: stated only that "this was not a clinical trial." |
| Smith 1972 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Smith 1977 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Smith 1987 | It was not possible to determine how many participants were allocated to each experimental group and attempts to obtain this information from the authors have been unsuccessful. |
| Smith 2019 | Not a randomised trial |
| Snyder 1984 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Stenhammar 2011 | Not a randomised trial |
| Suhre 1989 | Analyses by means of logit analysis and no useable outcome data were available. Author contacted: no useable data obtained |
| Sullivan 1995 | Comparison groups did not meet 'postal questionnaire' criteria. |
| Sutherland 1996 | There were too many differences between the two groups to be able to compare any of these differences without confounding. |
| Tan 1997 | Review article |
| TCTR20190814001 2019 | Not a randomised trial |
| Trice 1985 | Not a postal questionnaire |
| Tucker‐Seeley 2009 | Not a postal questionnaire |
| Udby 2021 | Not a randomised trial |
| Van Ryswyk 2016 | Not postal questionnaire |
| von Allmen 2019 | Not postal questionnaire |
| Walker 1977 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Wang 2018 | Not postal questionnaire |
| Ward 1994 | All comparisons in the study were confounded. |
| Warnock 2022 | Not postal questionnaire |
| Watson 1965 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Weiss 1985 | It was not possible to determine whether this study was randomised. Attempts to contact the author have been unsuccessful. |
| Weissenburger 1987 | It was not possible to determine whether this study was randomised. Contact details of the author were unavailable. |
| Weston 2017 | Not a randomised trial |
| Wildman 1977 | The comparison in this study was confounded by paper quality. |
| Willis 2013 | Not postal questionnaire |
| Wood 2017 | Not a randomised trial |
| Zagumny 1996 | Not a postal questionnaire |
| Zheng 2018 | Not postal questionnaire |
| Ziegenfuss 2012a | Not postal questionnaire |
| Zuidgeest 2011 | Not a randomised trial |
| Zwisler 2004 | Review article |
Characteristics of studies awaiting classification [ordered by study ID]
Alexander 2008.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Balabanis 2007.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Bauman 2016.
| Methods | Computer‐generated (using SAS statistical program) |
| Data | Adults aged 45 up to 110 years living in the state of New South Wales, Australia |
| Comparisons | Pre‐contact postcard, then questionnaire 2 weeks later; questionnaire then a reminder letter 2 weeks later; pre‐contact postcard then questionnaire 2 weeks later then a reminder letter 2 weeks later |
| Outcomes | Response after 14 days |
| Notes | 8 pages A one‐page reminder letter and the postcard provided brief information about the study, an invitation to participate, and were signed by the Study Scientific Director. Participants were provided with reply‐paid envelopes to return their completed questionnaires. |
Bhattarai 2010.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Bosnjak 2015.
| Methods | Random allocation: method not specified |
| Data | 562 undergraduate and graduate students enrolled at a German university |
| Comparisons | Email pre‐notification vs. SMS pre‐notification vs. no pre‐notification Email invitation vs. SMS invitation |
| Outcomes | Web surveys were sent out each month for 3 months. One week after invitations were sent out, non‐respondents were sent a reminder in the same mode as the designated invitation. |
| Notes | Questionnaire not described One group was contacted by SMS, the second one by email, and the third subsample served as a control group, receiving no pre‐notice. Students were then invited to participate by email or by SMS. |
Brusseleers 2019.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Burns 2015.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Damberg 2020.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Davidson 2019.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Dommeyer 2008.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Dudas 2012.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Duncan 2015.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Duncan 2017.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Edelman 2013a.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Epperson 1997.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes | Not yet assessed |
Finkelstein 2016.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Goodman 2017.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Griffin 2019.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Ho‐A‐Yun 2007.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Hopkins 1983.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
ISRCTN16642368 2016.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
ISRCTN31304930 2014.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
ISRCTN99859966 2018.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Joinson 2007.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Kaplowitz 2011.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Kelly 2010.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Koitsalu 2018.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Kozak 2020.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes | Not yet assessed |
Langeland 2019.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Maynard 1996.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes | Not yet assessed |
McCrohan 1981.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Mendoza 2014.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Muñoz‐Leiva 2010.
| Methods | Random allocation: method unspecified |
| Data | 1654 students of Business Management in Department of Marketing and Market Research, Faculty of Business and Economics, University of Granada, Spain |
| Comparisons | Personalised emails vs. standard More frequent (every 10 days) reminders vs. less frequent (every 20 days) reminders |
| Outcomes | Response after 2 months (5 reminders) |
| Notes | Over 44 items. Initial invitation email, 5 reminders |
Newton 1998.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
O'Keefe 1987.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Parast 2018.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Patrick 2021.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Porter 2007.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Price 2004a.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Price 2004b.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Price 2004c.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Price 2006.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Rach 1994.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Samel‐Kowalik 2012.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Siera 1988.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Strickland 1980.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Treat 1996.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Virtanen 2007.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
Wood 2015.
| Methods | Not yet assessed |
| Data | Not yet assessed |
| Comparisons | Not yet assessed |
| Outcomes | Not yet assessed |
| Notes |
SAS: Statistical Analysis System SMS: Short message service
Differences between protocol and review
There are no differences between the protocol and the review.
Contributions of authors
Ian Roberts, Mike Clarke, and Carolyn DiGuiseppi contributed to the conception of the review. Ian Roberts, Mike Clarke, Carolyn DiGuiseppi, and Phil Edwards contributed to the design of the review. Phil Edwards and Ian Roberts contributed to the co‐ordination of the review. Ian Roberts, Mike Clarke, Carolyn DiGuiseppi, Phil Edwards, Benjamin Woolf, and Chloe Perkins contributed to the search and selection of studies for inclusion in the review, as well as the collection of data for the review. Phil Edwards and Chloe Perkins contributed to the assessment of the risk of bias in the included studies. Phil Edwards contributed to the analysis of data, assessment of the certainty in the body of evidence, and interpretation of data. All authors contributed to the writing of the review.
Sources of support
Internal sources
-
London School of Hygiene & Tropical Medicine, UK
Salary support for Phil Edwards
External sources
-
The BUPA Foundation, UK
Research grant
-
The Nuffield Trust, UK
Short‐Term Fellowship
-
NIHR, UK
NIHR Evidence Synthesis Programme Grant NIHR133238
Declarations of interest
Phil Edwards: no relevant interests; involved in 'Woolf B, Edwards P. Does advance contact with research participants increase response to questionnaires: an updated systematic review and meta‐analysis. BMC Med Res Methodol. 2021;21(1):265. doi: 10.1186/s12874‐021‐01435‐2'.
Benjamin Woolf: no relevant interests; involved in 'Woolf B, Edwards P. Does pre‐notification increase questionnaire response rates: a randomised controlled trial nested within a systematic review. BMC Med Res Methodol. 2021;21(1):259. doi: 10.1186/s12874‐021‐01462‐z'.
Chloe Perkins: no relevant interests.
Ian Roberts: no relevant interests; former Editor of Cochrane Injuries (closed in March 2023).
Carolyn DiGuiseppi: no relevant interests; former Editor of Cochrane Injuries (closed in March 2023) until November 2020.
Mike Clarke: National Institute for Health and Care Research (grant/contract); Co‐ordinating Editor of Cochrane Methodology plus other Cochrane editorial roles but he was not involved in any part of the editorial process for this review update.
New search for studies and content updated (no change to conclusions)
References
References to studies included in this review
Aadahl 2003 {published data only}
- Aadahl M, Jørgensen T. The effect of conducting a lottery on questionnaire response rates: a randomised controlled trial. European Journal of Epidemiology 2003;18:941–4. [DOI] [PubMed] [Google Scholar]
Abdulaziz 2015 {published data only}
- Abdulaziz K, Brehaut J, Taljaard M, Emond M, Sirois M J, Lee J S, et al. National survey of physicians to determine the effect of unconditional incentives on response rates of physician postal surveys. BMJ OPEN 2015;5(2):e007166. [DOI] [PMC free article] [PubMed] [Google Scholar]
Adams 1982 {published data only}
- Adams LL, Gale D. Solving the quandary between questionnaire length and response rate in educational research. Research in Higher Education 1982;17(3):231-40. [Google Scholar]
Agarwal 2016 {published data only}
- Agarwal Arnav, Raad Dany, Kairouz Victor, Fudyma John, Curtis Anne B, Schunemann Holger J, et al. The effect of a monetary incentive for administrative assistants on the survey response rate: a randomized controlled trial. BMC medical research methodology 2016;16:94. [DOI] [PMC free article] [PubMed] [Google Scholar]
Akl 2005 {published data only}
- Akl E A, Maroun N, Klocke R A, Montori V, Schünemann H J. Electronic mail was not better than postal mail for surveying residents and faculty. J Clin Epidemiol 2005;58(4):425-9. [DOI] [PubMed] [Google Scholar]
Akl 2011 {published data only}
- Akl Elie A, Gaddam Swarna, Mustafa Reem, Wilson Mark C, Symons Andrew, Grifasi Ann, et al. The effects of tracking responses and the day of mailing on physician survey response rate: three randomized trials. PloS one 2011;6(2):e16942. [DOI] [PMC free article] [PubMed] [Google Scholar]
Albaum 1987 {published data only}
- Albaum G. Do source and anonymity affect mail survey results? Journal of the Academy of Marketing Science 1987;15(3):74-81. [Google Scholar]
Albaum 1989 {published data only}
- Albaum G, Strandskov J. Participation in a mail survey of international marketers: effects of pre-contact and detailed project explanation. Journal of Global Marketing 1989;2(4):7-23. [Google Scholar]
Allen 2016 {published data only}
- Allen P J, Roberts L D. The impact of academic sponsorship on Web survey dropout and item non-response. First Monday 2016;21(2):1. [Google Scholar]
Allen 2016a {published data only}
- Allen P J, Roberts L D. The impact of academic sponsorship on Web survey dropout and item non-response. First Monday 2016;21(2):1. [Google Scholar]
Alutto 1970 {published data only}
- Alutto JA. Some dynamics of questionnaire completion and return among professional and managerial personnel: the relative impacts of reception at work site or place of residence. Journal of Applied Psychology 1970;54(5):430-2. [Google Scholar]
Andreasen 1970 {published data only}
- Andreasen AR. Personalizing mail questionnaire correspondence. Public Opinion Quarterly 1970;34:273-7. [Google Scholar]
Antoun 2017 {published data only}
- Antoun C, Couper M P, Conrad F G. Effects of Mobile versus PC Web on Survey Response Quality. Public Opinion Quarterly 2017;81:280-306. [Google Scholar]
Arai 2016 {published data only}
- Arai Kiichiro, Yamada Kyohei. Examining the effect of providing a pen on the response rate to a mail survey. Behaviormetrika 2016;43(2):83-101. [Google Scholar]
Arzheimer 1999 {published data only}
- Arzheimer K, Klein M. The effect of material incentives on return rate, panel attrition and sample composition of a mail panel survey. International Journal of Public Opinion Research 1999;11(4):368-77. [Google Scholar]
Asch 1996 {published data only}
- Asch DA. Use of a coded postcard to maintain anonymity in a highly sensitive mail survey: cost, response rates, and bias. Epidemiology 1996;7(5):550-1. [PubMed] [Google Scholar]
Asch 1998 {published data only}
- Asch DA, Christakis NA, Ubel PA. Conducting physician mail surveys on a limited budget. A randomized trial comparing $2 bill versus $5 bill incentives. Medical Care 1998;36(1):95-9. [DOI] [PubMed] [Google Scholar]
Ashby 2011 {published data only}
- Ashby Rebecca, Turner Gwen, Cross Ben, Mitchell Natasha, Torgerson David. A randomized trial of electronic reminders showed a reduction in the time to respond to postal questionnaires. Journal of clinical epidemiology 2011;64(2):208-12. [DOI] [PubMed] [Google Scholar]
Ashing‐Giwa 2000 {published data only}
- Ashing-Giwa A, Ganz PA. Effect of timed incentives on subject participation in a study of long-term breast cancer survivors: are there ethnic differences? Journal of the National Medical Association 2000;92:528-32. [PMC free article] [PubMed] [Google Scholar]
Aveyard 2001 {published data only}
- Aveyard P, Manaseki S, Griffin C. The cost effectiveness of including pencils and erasers with self-completion epidemiological questionnaires. Public Health 2001;115:80-1. [DOI] [PubMed] [Google Scholar]
Bachman 1987 {published data only}
- Bachman DP. Cover letter appeals and sponsorship effects on mail survey response rates. Journal of Marketing Education 1987;9:45-51. [Google Scholar]
Bakan 2014 {published data only}
- Bakan Jennifer, Chen Bing, Medeiros-Nancarrow Cheryl, Hu Jim C, Kantoff Philip W, Recklitis Christopher J. Effects of a gift certificate incentive and specialized delivery on prostate cancer survivors' response rate to a mailed survey: a randomized-controlled trial. Journal of geriatric oncology 2014;5(2):127-32. [DOI] [PubMed] [Google Scholar]
Barker 1996 {published data only}
- Barker PJ, Cooper RF. Do sexual health questions alter the public's response to lifestyle questionnaires? Journal of Epidemiology and Community Health 1996;50:688. [DOI] [PMC free article] [PubMed] [Google Scholar]
Barra 2016 {published data only}
- Barra Mathias, Simonsen Tone Breines, Dahl Fredrik Andreas. Pre-contact by telephone increases response rates to postal questionnaires in a population of stroke patients: an open ended randomized controlled trial. BMC health services research 2016;16(1):506. [DOI] [PMC free article] [PubMed] [Google Scholar]
Basnov 2009 {published data only}
- Basnov M, Kongsved Sm Fau - Bech Per, Bech P Fau - Hjollund Niels Henrik, Hjollund N H. Reliability of short form-36 in an Internet- and a pen-and-paper version. Inform Health Soc Care 2009;34(1):53-8. [DOI] [PubMed] [Google Scholar]
Bauer 2004 {published data only}
- Bauer JE, Rezaishiraz H, Head K, Cowell J, Bepler G, Aiken M, et al. Obtaining DNA from a geographically dispersed cohort of current and former smokers: use of mail-based mouthwash collection and monetary incentives. Nicotine & Tobacco Research 2004;6:439-46. [DOI] [PubMed] [Google Scholar]
Bech 2009 {published data only}
- Bech M, Kristensen M B. Differential response rates in postal and web-based surveys among older respondents. Survey Research Methods 2009;3(1):1-6. [Google Scholar]
Becker 2000a {published and unpublished data}
- Becker H, Cookston J, Kulberg V. Mailed survey follow-ups - are postcard reminders more cost-effective than second questionnaires? Western Journal of Nursing Research 2000;22(5):642-7. [DOI] [PubMed] [Google Scholar]
Becker 2000b {published and unpublished data}
- Becker H, Cookston J, Kulberg V. Mailed survey follow-ups - are postcard reminders more cost-effective than second questionnaires? Western Journal of Nursing Research 2000;22(5):642-7. [DOI] [PubMed] [Google Scholar]
Beebe 2005a {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005a;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2005b {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005b;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2005c {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005c;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2005d {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005d;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2005e {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005e;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2005f {published data only}
- Beebe TJ, Davern ME, McAlpine DD, Call KT, Rockwood TH. Increasing response rates in a survey of medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). Medical Care 2005f;43(4):411-20. [DOI] [PubMed] [Google Scholar]
Beebe 2007 {published data only}
- Beebe TJ, Stoner SM, Anderson KJ, Williams AR. Selected questionnaire size and color combinations were significantly related to mailed survey response rates. Journal of Clinical Epidemiology 2007;60:1184-9. [DOI] [PubMed] [Google Scholar]
Beebe 2007a {published data only}
- Beebe Timothy J, Locke G Richard 3rd, Barnes Sunni A, Davern Michael E, Anderson Kari J. Mixing web and mail methods in a survey of physicians. Health services research 2007;42(3 Pt 1):1219-34. [DOI] [PMC free article] [PubMed] [Google Scholar]
Beebe 2010 {published data only}
- Beebe Timothy J, Rey Enrique, Ziegenfuss Jeanette Y, Jenkins Sarah, Lackore Kandace, Talley Nicholas J, et al. Shortening a survey and using alternative forms of prenotification: impact on response rate and quality. BMC medical research methodology 2010;10:50. [DOI] [PMC free article] [PubMed] [Google Scholar]
Beebe 2018 {published data only}
- Beebe Timothy J, Jacobson Robert M, Jenkins Sarah M, Lackore Kandace A, Rutten Lila J Finney. Testing the Impact of Mixed-Mode Designs (Mail and Web) and Multiple Contact Attempts within Mode (Mail or Web) on Clinician Survey Response. Health services research 2018;53 Suppl 1(g2l, 0053006):3070-83. [DOI] [PMC free article] [PubMed] [Google Scholar]
Bell 2004 {published data only}
- Bell LS, Butler TL, Herring RP, Yancey AK, Fraser GE. Recruiting blacks to the adventist health study: do follow-up phone calls increase response rates? Annals of Epidemiology 2005;15(9):667–72. [DOI] [PubMed] [Google Scholar]
Bell 2016 {published data only}
- Bell K, Clark L, Fairhurst C, Mitchell N, Lenaghan E, Blacklock J, et al. Enclosing a pen reduced time to response to questionnaire mailings. JOURNAL OF CLINICAL EPIDEMIOLOGY 2016;74:144-50. [DOI] [PubMed] [Google Scholar]
Bellizzi 1986 {published data only}
- Bellizzi JA, Hite RE. Face-to-face advance contact and monetary incentives: effects on mail survey return rates, response differences, and survey costs. Journal of Business Research 1986;14:99-106. [Google Scholar]
Berdie 1973 {published data only}
- Berdie DR. Questionnaire length and response rate. Journal of Applied Psychology 1973;58(2):278-80. [Google Scholar]
Bergen 1957 {published data only}
- Bergen AV, Spitz JC. The introduction of a written survey [De introductie van een schriftelijke enquete]. Nederlandsch Tijdschrift voor Psychologie 1957;12:68-96. [PubMed] [Google Scholar]
Bergeson 2013 {published data only}
- Bergeson SC, Gray J, Ehrmantraut LA, Laibson T, Hays RD. Comparing Web-based with Mail Survey Administration of the Consumer Assessment of Healthcare Providers and Systems (CAHPS R) Clinician and Group Survey. Primary Health Care 2013;15(3):1000132. [DOI] [PMC free article] [PubMed] [Google Scholar]
Berk 1993 {published data only}
- Berk ML, Edwards WS, Gay NL. The use of a prepaid incentive to convert non responders on a survey of physicians. Evaluation & the Health Professions 1993;16:239-45. [DOI] [PubMed] [Google Scholar]
Berry 1987 {published data only}
- Berry S. Physician response to a mailed survey. An experiment in timing of payment. Public Opinion Quarterly 1987;51:102-14. [Google Scholar]
Beydoun 2006 {published data only}
- Beydoun H, Saftlas AF, Harland K, Triche E. Combining conditional and unconditional recruitment incentives could facilitate telephone tracing in surveys of postpartum women. Journal of Clinical Epidemiology 2006;59:732–8. [DOI] [PubMed] [Google Scholar]
Bhandari 2003 {published data only}
- Bhandari M, Swiontkowski MF, Shankardass K, Sprague S, Schemitsch EH, Guyatt GH. A randomized trial of opinion leader endorsement in a survey of orthopaedic surgeons: effect on primary response rates. International Journal of Epidemiology 2003;32:634–6. [DOI] [PubMed] [Google Scholar]
Biner 1988 {published data only}
- Biner PM. Effects of cover letter appeal and monetary incentives on survey response: a reactance theory application. Basic and Applied Social Psychology 1988;9(2):99-106. [Google Scholar]
Biner 1990 {published data only}
- Biner PM, Barton DL. Justifying the enclosure of monetary incentives in mail survey cover letters. Psychology & Marketing 1990;7(3):153-62. [Google Scholar]
Biner 1994 {published data only}
- Biner PM, Kidd HJ. The interactive effects of monetary incentive justification and questionnaire length on mail survey response rates. Psychology & Marketing 1994;11(5):483-92. [Google Scholar]
Birnholtz 2004 {published data only}
- Birnholtz JP, Horn DB, Finholt TA, Bae SJ. The effect of cash, electronic, and paper gift certificates as respondent incentives for a web based survey of technologically sophisticated respondents. Social Science Computer Review 2004;22:355-62. [Google Scholar]
Bjertnaes 2012 {published data only}
- Bjertnaes O A, Iversen H H. User-experience surveys with maternity services: a randomized comparison of two data collection models. INTERNATIONAL JOURNAL FOR QUALITY IN HEALTH CARE 2012;24(4):433-8. [DOI] [PubMed] [Google Scholar]
Bjertnaes 2018 {published data only}
- Bjertnaes Oyvind, Iversen Hilde Hestad, Skrivarhaug Torild. A randomized comparison of three data collection models for the measurement of parent experiences with diabetes outpatient care. BMC Medical Research Methodology 2018;18(1):N.PAG. [DOI] [PMC free article] [PubMed] [Google Scholar]
Blass 1981 {published data only}
- Blass T, Leichtman SR, Brown RA. The effect of perceived consensus and implied threat upon responses to mail surveys. Journal of Social Psychology 1981;113:213-6. [Google Scholar]
Blass‐Wilhems 1982 {published data only}
- Blass-Wilhelms W. Influence of 'real' postage stamp versus stamp 'postage paid' on return rate of response cards [Der EinfluB der Frankierungsart auf Rucklauf von Antwortkarten]. Zeitschrift fur Soziologie 1982;11(1):64-8. [Google Scholar]
Blomberg 1996 {published data only}
- Blomberg J, Sandell R. Does a material incentive affect response on a psychotherapy follow-up questionnaire? Psychotherapy Research 1996;6(3):155-63. [Google Scholar]
Blumenberg 2019 {published data only}
- Blumenberg C, Menezes A M B, Goncalves H, Assuncao M C F, Wehrmeister F C, Barros F C, et al. The role of questionnaire length and reminders frequency on response rates to a web-based epidemiologic study: a randomised trial. INTERNATIONAL JOURNAL OF SOCIAL RESEARCH METHODOLOGY 2019;22(6):625-35. [Google Scholar]
Blythe 1986 {published data only}
- Blythe BJ. Increasing mailed survey responses with a lottery. Social Work Research Abstracts 1986;22:18-9. [Google Scholar]
Bolt 2014 {published data only}
- Bolt E E, Heide A, Onwuteaka-Philipsen B D. Reducing questionnaire length did not improve physician response rate: a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2014;67(4):477-81. [DOI] [PubMed] [Google Scholar]
Bond 2020 {published data only}
- Bond D M, Hammond J, Shand A W, Nassar N. Comparing a Mobile Phone Automated System With a Paper and Email Data Collection System: substudy within a Randomized Controlled Trial. JMIR Mhealth Uhealth 2020;8(8):e15284. [DOI] [PMC free article] [PubMed] [Google Scholar]
Bonevski 2011 {published data only}
- Bonevski B, Magin P, Horton G, Foster M, Girgis A. Response rates in GP surveys Trialling two recruitment strategies. AUSTRALIAN FAMILY PHYSICIAN 2011;40(6):427-30. [PubMed] [Google Scholar]
Bonevski 2011a {published data only}
- Bonevski B, Magin P, Horton G, Foster M, Girgis A. Response rates in GP surveys Trialling two recruitment strategies. AUSTRALIAN FAMILY PHYSICIAN 2011;40(6):427-30. [PubMed] [Google Scholar]
Boser 1990 {published data only}
- Boser JA. Surveying alumni by mail: effect of booklet/folder questionnaire format and style of type on response rate. Research in Higher Education 1990;31(2):149-59. [Google Scholar]
Bosnjak 2003 {published data only}
- Bosnjak M, Tuten TL. Prepaid and promised incentives in web surveys: an experiment. Social Science Computer Review 2003;21:208-17. [Google Scholar]
Boulianne 2012 {published data only}
- Boulianne Shelley. Examining the Gender Effects of Different Incentive Amounts in a Web Survey. FIELD METHODS 2012;25(1):91-104. [Google Scholar]
Boyd 2015 {published data only}
- Boyd A, Tilling K, Cornish R, Davies A, Humphries K, Macleod J. Professionally designed information materials and telephone reminders improved consent response rates: evidence from an RCT nested within a cohort study. JOURNAL OF CLINICAL EPIDEMIOLOGY 2015;68(8):877-87. [DOI] [PMC free article] [PubMed] [Google Scholar]
Boyle 2012 {published data only}
- Boyle T, Heyworth J, Landrigan J, Mina R, Fritschi L. The Effect of Lottery Scratch Tickets and Donation Offers on Response Fraction: A Study and Meta-Analysis. FIELD METHODS 2012;24(1):112-32. [Google Scholar]
Bradshaw 2020 {published data only}
- Bradshaw L E, Montgomery A A, Williams H C, Chalmers J R, Haines R H. Two-by-two factorial randomised study within a trial (SWAT) to evaluate strategies for follow-up in a randomised prevention trial. TRIALS 2020;21(1):529. [DOI] [PMC free article] [PubMed] [Google Scholar]
Bray 2017 {published data only}
- Bray I, Noble S, Robinson R, Molloy L, Tilling K. Mode of delivery affected questionnaire response rates in a birth cohort study. JOURNAL OF CLINICAL EPIDEMIOLOGY 2017;81:64-71. [DOI] [PMC free article] [PubMed] [Google Scholar]
Bredart 2002 {published data only}
- Bredart A, Razavi D, Robertson C, Brignone S, Fonzo D, Petit J-Y, et al. Timing of patient satisfaction assessment: effect on questionnaire acceptability, completeness of data, reliability and variability of scores. Patient Education and Counseling 2002;46:131-6. [DOI] [PubMed] [Google Scholar]
Breen 2010 {published data only}
- Breen C L, Shakeshaft A P, Doran C M, Sanson-Fisher R W, Mattick R P. Cost-effectiveness of follow-up contact for a postal survey: a randomised controlled trial. AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2010;34(5):508-12. [DOI] [PubMed] [Google Scholar]
Brehaut 2006 {published data only}
- Brehaut JC, Graham ID, Visentin L, Stiell IG. Print format and sender recognition were related to survey completion rate. Journal of Clinical Epidemiology 2006;59:635–41. [DOI] [PubMed] [Google Scholar]
Brems 2006 {published data only}
- Brems C, Johnson ME, Warner T. Survey return rates as a function of priority versus first-class mailing. Psychological Reports 2006;99:496-501. [DOI] [PubMed] [Google Scholar]
Brennan 1991 {published data only}
- Brennan M, Hoek J, Astridge C. The effects of monetary incentives on the response rate and cost-effectiveness of a mail survey. Journal of the Market Research Society 1991;33:229-41. [Google Scholar]
Brennan 1992a {published data only}
- Brennan M. The effect of a monetary incentive on mail survey response rates. Journal of the Market Research Society 1992;34(2):173-7. [Google Scholar]
Brennan 1992b {published data only}
- Brennan M. The effect of a monetary incentive on mail survey response rates. Journal of the Market Research Society 1992;34(2):173-7. [Google Scholar]
Brennan 1992c {published data only}
- Brennan M. The effect of a monetary incentive on mail survey response rates. Journal of the Market Research Society 1992;34(2):173-7. [Google Scholar]
Brennan 1993a {published data only}
- Brennan M, Seymour P, Gendall P. The effectiveness of monetary incentives in mail surveys: further data. Marketing Bulletin 1993;4:43-52. [Google Scholar]
Brennan 1993b {published data only}
- Brennan M, Seymour P, Gendall P. The effectiveness of monetary incentives in mail surveys: further data. Marketing Bulletin 1993;4:43-52. [Google Scholar]
Brennan 2009 {published data only}
- Brennan Mike, Charbonneau Jan. Improving Mail Survey Response Rates Using Chocolate and Replacement Questionnaires. The Public Opinion Quarterly 2009;73(2):368-78. [Google Scholar]
Bright 2002 {published data only}
- Bright KD, Smith PM. The use of incentives to affect response rates for a mail survey of US marina decision makers. Forest Products Journal 2002;52(10):26-9. [Google Scholar]
Brook 1978 {published data only}
- Brook LL. The effect of different postage combinations on response levels and speed of reply. Journal of the Market Research Society 1978;20:238-44. [Google Scholar]
Brookes 2018a {published data only}
- Brookes Sara T, Chalmers Katy A, Avery Kerry N L, Coulman Karen, Blazeby Jane M, group Romio study. Impact of question order on prioritisation of outcomes in the development of a core outcome set: a randomised controlled trial. Trials 2018;19(1):66. [DOI] [PMC free article] [PubMed] [Google Scholar]
Brookes 2018b {published data only}
- Brookes Sara T, Chalmers Katy A, Avery Kerry N L, Coulman Karen, Blazeby Jane M, group Romio study. Impact of question order on prioritisation of outcomes in the development of a core outcome set: a randomised controlled trial. Trials 2018;19(1):66. [DOI] [PMC free article] [PubMed] [Google Scholar]
Brown 1965 {published data only}
- Brown ML. Use of a postcard query in mail surveys. Public Opinion Quarterly 1965;29:635-637. [Google Scholar]
Brown 1975 {published data only}
- Brown GH. Randomised inquiry vs conventional questionnaire method in estimating drug usage rates through mail surveys (Technical Report). Human Resources Research Organisation (HumRRO). US Army Research Institute for the behavioural & Social Sciences, Virginia 1975.
Bruce 2000 {published data only}
- Bruce T, Salkeld G, Short L, Solomon M, Ward J. A randomised trial of telephone versus postcard prompts to enhance response rate in a phased population-based study about community preferences. Australian and New Zealand Journal of Public Health 2000;24(4):456-7. [DOI] [PubMed] [Google Scholar]
Brøgger 2007 {published data only}
- Brøgger J, Nystad W, Cappelen I, Bakke P. No increase in response rate by adding a web response option to a postal population survey: A randomized trial. Jornal of Medical Internet Research 2007;9(5):e40. [DOI] [PMC free article] [PubMed] [Google Scholar]
Buchman 1982 {published data only}
- Buchman TA, Tracy JA. Obtaining responses to sensitive questions: conventional questionnaire versus randomized response technique. Journal of Accounting Research 1982;20(1):263-271. [Google Scholar]
Burgess 2012 {published data only}
- Burgess Caroline, Nicholas Jennifer, Gulliford Martin. Impact of an electronic, computer-delivered questionnaire, with or without postal reminders, on survey response rate in primary care. Journal of Epidemiology and Community Health 2012;66(7):663-4. [DOI] [PubMed] [Google Scholar]
Burns 1980 {published data only}
- Burns AC, Hair JF. An analysis of mail survey responses from a commercial sample. American Institute Decision Science 1980;1:227-9. [Google Scholar]
Buttle 1997 {published data only}
- Buttle F, Thomas G. Questionnaire colour and mail survey response rate. Journal of the Market Research Society 1997;39(4):625-6. [Google Scholar]
Cabana 2000 {published data only}
- Cabana MD, Becher O, Rubin HR, Freed GL. Effect of repeated presentations of a study logo on physician survey response rate. Pediatric Research 2000;47(4):p843. [Google Scholar]
Campbell 1990 {published data only}
- Campbell MJ, Waters WE. Does anonymity increase response rate in postal questionnaire surveys about sensitive subjects? A randomised trial. Journal of Epidemiology and Community Health 1990;44:75-76. [DOI] [PMC free article] [PubMed] [Google Scholar]
Camunas 1990 {published data only}
- Camunas C, Alward RR, Vecchione E. Survey response rates to a professional association mail questionnaire. Journal of the New York State Nurses Association 1990;21(3):7-9. [PubMed] [Google Scholar]
Carling 2004 {published data only}
- Carling C. International Questionnaire Postal Response Rate: An experiment comparing no return postage to provision of International Postage Vouchers - "Coupon-Reponse International". BMC Health Services Research 2004;4(16):1-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
Carpenter 1974 {published data only}
- Carpenter EH. Personalizing mail surveys: a replication and reassessment. Public Opinion Quarterly 1974;38:614-620. [Google Scholar]
Carpenter 1977 {published data only}
- Carpenter EH. Evaluation of mail questionnaires for obtaining data from more than one respondent in a household. Rural Sociology 1977;42(2):250-9. [Google Scholar]
Cartwright 1986 {published data only}
- Cartwright A. Some experiments with factors that might affect the response of mothers to a postal questionnaire. Statistics in Medicine 1986;5:607-17. [DOI] [PubMed] [Google Scholar]
Cartwright 1987 {published data only}
- Cartwright A, Smith C. Identifying a sample of elderly people by a postal screen. Age & Ageing 1987;16:119-22. [DOI] [PubMed] [Google Scholar]
Chan 2003 {published data only}
- Chan TMT, Tse SHM, Day MC, Tong ETF, Suen LKP. Randomized trial of use of incentive to increase the response rate to a mailed survey. Asian Journal of Nursing Studies 2003;6(3):36-43. [Google Scholar]
Chan 2018 {published data only}
- Chan R C H, Mak W W S, Pang I H Y, Wong S Y S, Tang W K, Lau J T F, et al. Utility and Cost-effectiveness of Motivational Messaging to Increase Survey Response in Physicians: A Randomized Controlled Trial. FIELD METHODS 2018;30(1):37-55. [Google Scholar]
Chebat 1991 {published data only}
- Chebat J-C, Picard J. Does prenotification increase response rates in mail surveys? A self-perception approach. Journal of Social Psychology 1991;13(4):477-81. [Google Scholar]
Chen 1984 {published data only}
- Chen C. Questionnaire length, salience and researchers' authority, and follow-up: the effect on response rates for postal questionnaires. Chinese Journal of Psychology 1984;26(2):77-84. [Google Scholar]
Childers 1979 {published data only}
- Childers TL, Skinner SJ. Gaining respondent cooperation in mail surveys through prior commitment. Public Opinion Quarterly 1979;43:558-61. [Google Scholar]
Childers 1980a {published data only}
- Childers TL, Pride WM, Ferrell OC. A reassessment of the effects of appeals on response to mail surveys. Journal of Marketing Research 1980;17:365-70. [Google Scholar]
Childers 1980b {published data only}
- Childers TL, Pride WM, Ferrell OC. A reassessment of the effects of appeals on response to mail surveys. Journal of Marketing Research 1980;17:365-70. [Google Scholar]
Childers 1985 {published data only}
- Childers TL, Skinner SJ. Theoretical and empirical issues in the identification of survey respondents. Journal of the Market Research Society 1985;27(1):39-53. [Google Scholar]
Childers TL 1979 {published data only}
- Childers TL, Ferrell OC. Response rates and perceived questionnaire length in mail surveys. Journal of Marketing Research 1979;16:429-31. [Google Scholar]
Choi 1990 {published data only}
- Choi BC, Pak AW, Purdham JT. Effects of mailing strategies on response rate, response time, and cost in a questionnaire study among nurses. Epidemiology 1990;1(1):72-4. [DOI] [PubMed] [Google Scholar]
Choudhury 2012 {published data only}
- Choudhury Yasmin, Hussain Iqbal, Parsons Suzanne, Rahman Anisur, Eldridge Sandra, Underwood Martin. Methodological challenges and approaches to improving response rates in population surveys in areas of extreme deprivation. Primary health care research & development 2012;13(3):211-8. [DOI] [PubMed] [Google Scholar]
Christensen 2019 {published data only}
- Christensen Anne Illemann, Lynn Peter, Tolstrup Janne Schurmann. Can targeted cover letters improve participation in health surveys? Results from a randomized controlled trial. BMC medical research methodology 2019;19(1):151. [DOI] [PMC free article] [PubMed] [Google Scholar]
Christie 1985 {unpublished data only}
- Christie SC. An analysis of three different treatments on the response rate of a mail survey. Student Research Report, Department of Marketing, Massey University 1985.
Church 2004 {published data only}
- Church TR, Yeazel MW, Jones RM, Kochevar LK, Watt GD, Mongin SJ, et al. A randomized trial of direct mailing of fecal occult blood tests to increase colorectal cancer screening. Journal of the National Cancer Institute 2004;96(10):770-80. [DOI] [PubMed] [Google Scholar]
Clark 2001 {published data only}
- Clark TJ, Khan KS, Gupta JK. Provision of pen along with questionnaire does not increase the response rate to a postal survey: a randomised controlled trial. Journal of Epidemiology and Community Health 2001;55:595-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clark 2011 {published data only}
- Clark Melissa, Rogers Michelle, Foster Andrew, Dvorchak Faye, Saadeh Frances, Weaver Jessica, et al. A randomized trial of the impact of survey design characteristics on response rates among nursing home providers. Evaluation & the health professions 2011;34(4):464-86. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clark 2015 {published data only}
- Clark Laura, Ronaldson Sarah, Dyson Lisa, Hewitt Catherine, Torgerson David, Adamson Joy. Electronic prompts significantly increase response rates to postal questionnaires: a randomized trial within a randomized trial and meta-analysis. Journal of clinical epidemiology 2015;68(12):1446-50. [DOI] [PubMed] [Google Scholar]
Clarke 1998 {published data only}
- Clarke R, Breeze E, Sherliker P, Shipley M, Youngman L. Design, objectives, and lessons from a pilot 25 year follow up re-survey of survivors in the Whitehall study of London civil servants. Journal of Epidemiology and Community Health 1998;52:364-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clarke 2007 {published data only}
- Clarke M, Clarke L, Clarke T. Yes Sir, no Sir, not much difference Sir. Journal of the Royal Society of Medicine 2007;100(12):571-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clark TJ 2001 {published data only}
- Clark TJ, Khan KS, Gupta JK. Effect of paper quality on the response rate to a postal survey: a randomised controlled trial. BMC Medical Research Methodology 2001;1:12. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clausen 1947 {published data only}
- Clausen JA, Ford RN. Controlling bias in mail questionnaires. Journal of the American Statistical Association 1947;42(240):497-511. [Google Scholar]
Claycomb 2000 {published data only}
- Claycomb C, Porter SS, Martin CL. Riding the wave: response rates and the effects of time intervals between successive mail survey follow-up efforts. Journal of Business Research 2000;48:157-62. [Google Scholar]
Cleopas 2006 {published data only}
- Cleopas A, Kolly V, Perneger TV. Longer response scales improved the acceptability and performance of the Nottingham Health Profile. Journal of Clinical Epidemiology 2006;59(11):1183-90. [DOI] [PubMed] [Google Scholar]
Coast 2006 {published data only}
- Coast Joanna, Flynn Terry N, Salisbury Chris, Louviere Jordan, Peters Tim J. Maximising Responses to Discrete Choice Experiments: A Randomised Trial. Applied Health Economics and Health Policy 2006;5(4):249-60. [DOI] [PubMed] [Google Scholar]
Cobanoglu 2001 {published data only}
- Cobanoglu Cihan, Moreo Patrick J, Warde Bill. A Comparison of Mail, Fax and Web-Based Survey Methods. International Journal of Market Research 2001;43(4):1-15. [Google Scholar]
Cobanoglu 2003 {published data only}
- Cobanoglu C, Cobanoglu N. The effect of incentives in websurveys: application and ethical considerations. International Journal of Market Research 2003;45(4):475-88. [Google Scholar]
Cochrane 2020 {published data only}
- Cochrane Ann, Welch Charlie, Fairhurst Caroline, Cockayne Sarah, Torgerson David J, Group Otis Study. An evaluation of a personalised text message reminder compared to a standard text message on postal questionnaire response rates: an embedded randomised controlled trial. F1000Research 2020;9(101594320):154. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cockayne 2005 {published data only}
- Cockayne S, Torgerson DJ. A randomised controlled trial to assess the effectiveness of offering study results as an incentive to increase response rates to postal questionnaires. BMC Medical Research Methodology 2005;5(34):1-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cohen 2019 {published data only}
- Cohen Andrew J, Washington Sam, Butler Christi, Kamal Puneet, Patino German, Tresh Anas, et al. Altruistic donation to improve survey responses: a global randomized trial. BMC research notes 2019;12(1):113. [DOI] [PMC free article] [PubMed] [Google Scholar]
Collins 2000 {published data only}
- Collins RL, Ellickson PL, Hays RD, McCaffrey DF. Effects on incentive size and timing on response rates to a follow-up wave of a longitudinal mailed survey. Evaluation Review 2000;24(4):347-63. [DOI] [PubMed] [Google Scholar]
Conner 2017 {published data only}
- Conner M, Sandberg T, Nekitsing C, Hutter R, Wood C, Jackson C, et al. Varying cognitive targets and response rates to enhance the question-behaviour effect: An 8-arm Randomized Controlled Trial on influenza vaccination uptake. SOCIAL SCIENCE & MEDICINE 2017;180:135-42. [DOI] [PubMed] [Google Scholar]
Converse 2008 {published data only}
- Converse Patrick D, Wolfe Edward W, Xiaoting Huang, Oswald Frederick L. Response Rates for Mixed-Mode Surveys Using Mail and E-mail/Web. American Journal of Evaluation 2008;29(1):99-107. [Google Scholar]
Cook 2016 {published data only}
- Cook David A, Wittich Christopher M, Daniels Wendlyn L, West Colin P, Harris Ann M, Beebe Timothy J. Incentive and Reminder Strategies to Improve Response Rate for Internet-Based Physician Surveys: A Randomized Experiment. Journal of medical Internet research 2016;18(9):e244. [DOI] [PMC free article] [PubMed] [Google Scholar]
Corcoran 1985 {published data only}
- Corcoran KJ. Enhancing the response rate in survey research. Social Work Research & Abstracts 1985;21:2. [Google Scholar]
Coryn 2020 {published data only}
- Coryn Chris L S, Becho Lyssa W, Westine Carl D, Mateu Pedro F, Abu-Obaid Ruqayyah N, Hobson Kristin A, et al. Material incentives and other potential factors associated with response rates to internet surveys of American Evaluation Association members: Findings from a randomized experiment. American Journal of Evaluation 2020;41(2):277-96. [Google Scholar]
Cosgrove 2018 {published data only}
- Cosgrove John A. Using a Small Cash Incentive to Increase Survey Response. Administration and policy in mental health 2018;45(5):813-9. [DOI] [PubMed] [Google Scholar]
Cotterill 2017 {published data only}
- Cotterill S, Howells K, Rhodes S, Bower P. The effect of using social pressure in cover letters to improve retention in a longitudinal health study: an embedded randomised controlled retention trial. TRIALS 2017;18:341. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cottrell 2015 {published data only}
- Cottrell E, Roddy E, Rathod T, Thomas E, Porcheret M, Foster N E. Maximising response from GPs to questionnaire surveys: do length or incentives make a difference? BMC MEDICAL RESEARCH METHODOLOGY 2015;15:3. [DOI] [PMC free article] [PubMed] [Google Scholar]
Coughlin 2011 {published data only}
- Coughlin Steven, Aliaga Pablo, Barth Shannon, Eber Stephanie, Maillard Jessica, Mahan Clare, et al. The Effectiveness of a Monetary Incentive on Response Rates in a Survey of Recent U.S. Veterans. Survey practice 2011;4:1-8. [Google Scholar]
Cox 1974 {published data only}
- Cox EP, Anderson T, Fulcher DG. Reappraising mail survey response rates. Journal of Marketing Research 1974;11:413-7. [Google Scholar]
Crittenden 1985 {published data only}
- Crittenden WF, Crittenden VL, Hawes JM. Examining the effects of questionnaire color and print font on mail survey response rates. Akron Business and Economic Review 1985;16(4):31-56. [Google Scholar]
Cunningham‐Burley 2020 {published data only}
- Cunningham-Burley Rachel, Roche Jenny, Fairhurst Caroline, Cockayne Sarah, Hewitt Catherine, Iles-Smith Heather, et al. Enclosing a pen to improve response rate to postal questionnaire: an embedded randomised controlled trial. F1000Research 2020;9(101594320):577. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cureton 2021 {published data only}
- Cureton L, Marian I R, Barber V S, Parker A, Torgerson D J, Hopewell S. Randomised study within a trial (SWAT) to evaluate personalised versus standard text message prompts for increasing trial participant response to postal questionnaires (PROMPTS). TRIALS 2021;22(1):502. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cycyota 2002 {published data only}
- Cycyota C, Harrison DA. Enhancing survey response rates at the executive level: Are employee- or consumer-level techniques effective? Journal of Management 2002;28(2):151-76. [Google Scholar]
Danko 2019 {published data only}
- Danko Kristin J, Dahabreh Issa J, Ivers Noah M, Moher David, Grimshaw Jeremy M. Contacting authors by telephone increased response proportions compared with emailing: results of a randomized study. Journal of clinical epidemiology 2019;115(jce, 8801383):150-9. [DOI] [PubMed] [Google Scholar]
Deehan 1997 {published data only}
- Deehan A, Templeton L, Taylor C, Drummond C, Strang J. The effect of cash and other financial inducements on the response rate of general practitioners in a national postal study. British Journal of General Practice 1997;47:87-90. [PMC free article] [PubMed] [Google Scholar]
Delnevo 2004 {published data only}
- Delnevo CD, Abatemarco DJ, Steinberg MB. Physician response rates to a mail survey by specialty and timing of incentive. American Journal of Preventive Medicine 2004;26(3):234-6. [DOI] [PubMed] [Google Scholar]
Delnevo 2021 {published data only}
- Delnevo CD, Singh B. The effect of a web-push survey on physician survey responses rates: a randomized experiment. Survey practice 2021;14(1):10.29115/sp-2021-0001. [DOI] [PMC free article] [PubMed] [Google Scholar]
Del Valle 1997 {published data only}
- Del Valle ML, Morgenstern H, Rogstad TL, Albright C, Vickrey BG. A randomised trial of the impact of certified mail on response rate to a physician survey, and a cost-effectiveness analysis. Evaluation & the Health Professions 1997;20(4):389-406. [DOI] [PubMed] [Google Scholar]
Denton 1988 {published data only}
- Denton J, Tsai C-Y, Chevrette P. Effects on survey responses of subjects, incentives, and multiple mailings. Journal of Experimental Education 1988;56:77-82. [Google Scholar]
Denton 1991 {published data only}
- Denton JJ, Tsai C-Y. Two investigations into the influence of incentives and subject characteristics on mail survey responses in teacher education. Journal of Experimental Education 1991;59:352-66. [Google Scholar]
Deutskens 2004a {published data only}
- Deutskens E, Ruyter KD, Wetzels M, Oosterveld P. Response rate and response quality of internet-based surveys: an experimental study. Marketing Letters 2004;15(1):21-36. [Google Scholar]
Deutskens 2004b {published data only}
- Deutskens E, Ruyter KD, Wetzels M, Oosterveld P. Response rate and response quality of internet-based surveys: an experimental study. Marketing Letters 2004;15(1):21-36. [Google Scholar]
Dillman 1974a {published data only}
- Dillman DA, Frey JH. Contribution of personalization to mail questionnaire response as an element of a previously tested method. Journal of Applied Psychology 1974;59(3):297-301. [Google Scholar]
Dillman 1974b {published data only}
- Dillman DA, Frey JH. Contribution of personalization to mail questionnaire response as an element of a previously tested method. Journal of Applied Psychology 1974;59(3):297-301. [Google Scholar]
Dillman 1993 {published data only}
- Dillman DA, Sinclair MD, Clark JR. Effects of questionnaire length, respondent-friendly design, and a difficult question on response rates for occupant-addressed census mail surveys. Public Opinion Quarterly 1993;57(3):289-304. [Google Scholar]
Dillman 1996 {published data only}
- Dillman DA, Singer E, Clark JR, Treat JB. Effects of benefits appeals, mandatory appeals, and variations in statements of confidentiality on completion rates for census questionnaires. Public Opinion Quarterly 1996;60:376-89. [Google Scholar]
Dinglas 2015 {published data only}
- Dinglas V D, Huang M, Sepulveda K A, Pinedo M, Hopkins R O, Colantuoni E, et al. Personalized contact strategies and predictors of time to survey completion: Analysis of two sequential randomized trials Study design. BMC Medical Research Methodology 2015;15(1):5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Dirmaier 2007 {published data only}
- Dirmaier J, Harfst T, Koch U, Schulz H. Incentives increased return rates but did not influence partial nonresponse or treatment outcome in a randomized trial. Journal of Clinical Epidemiology 2007;60:1263-70. [DOI] [PubMed] [Google Scholar]
Dodd 1987 {published data only}
- Dodd DK, Markwiese BJ. Survey response rate as a function of personalized signature on cover letter. Journal of Social Psychology 1987;127(1):97-8. [Google Scholar]
Doerfling 2010 {published data only}
- Doerfling Paul, Kopec Jacek A, Liang Matthew H, Esdaile John M. The effect of cash lottery on response rates to an online health survey among members of the Canadian Association of Retired Persons: a randomized experiment. Canadian journal of public health = Revue canadienne de sante publique 2010;101(3):251-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Dommeyer 1980a {unpublished data only}
- Dommeyer CJ. Experimentation on threatening appeals in the follow-up letters of a mail survey. Doctoral Dissertation 1980.
Dommeyer 1980b {unpublished data only}
- Dommeyer CJ. Experimentation on threatening appeals in the follow-up letters of a mail survey. Doctoral Dissertation 1980.
Dommeyer 1985 {published data only}
- Dommeyer CJ. Does response to an offer of mail survey results interact with questionnaire interest? Journal of the Market Research Society 1985;27(1):27-38. [Google Scholar]
Dommeyer 1987 {published data only}
- Dommeyer CJ. The effects of negative cover letter appeals on mail survey response. Journal of the Market Research Society 1987;29(4):445-51. [Google Scholar]
Dommeyer 1988 {published data only}
- Dommeyer CJ. How form of the monetary incentive affects mail survey response. Journal of the Market Research Society 1988;30(3):379-85. [Google Scholar]
Dommeyer 1989 {published data only}
- Dommeyer CJ. Offering mail survey results in a lift letter. Journal of the Market Research Society 1989;31(3):399-408. [Google Scholar]
Dommeyer 1991 {published data only}
- Dommeyer CJ, Elganayan D, Umans C. Increasing mail survey response with an envelope teaser. Journal of the Market Research Society 1991;33(2):137-40. [Google Scholar]
Dommeyer 1996 {published data only}
- Dommeyer CJ, Ruggiero LA. The effects of a photograph on mail survey response. Marketing Bulletin 1996;7:51-7. [Google Scholar]
Dommeyer 2004 {published data only}
- Dommeyer CJ, Baum P, Hanna RW, Chapman KS. Gathering faculty teaching evaluations by in-class and online surveys: their effects on response rates and evaluations. Assessment & Evaluation in Higher Education 2004;29(5):611-23. [Google Scholar]
Donaldson 1999 {published data only}
- Donaldson GW, Moinpour CM, Bush NE, Chapko M, Jocom J, Siadak M, et al. Physician participation in research surveys: a randomized study of inducements to return mailed research questionnaires. Evaluation & the Health Professions 1999;22(4):427-41. [DOI] [PubMed] [Google Scholar]
Doob 1971a {published data only}
- Doob A, Zabrack M. The effect of freedom-threatening instructions and monetary inducement on compliance. Canadian Journal of Behavioural Science 1971;3(4):408-12. [Google Scholar]
Doob 1971b {published data only}
- Doob A, Zabrack M. The effect of freedom-threatening instructions and monetary inducement on compliance. Canadian Journal of Behavioural Science 1971;3(4):408-12. [Google Scholar]
Doob 1971c {published data only}
- Doob A, Zabrack M. The effect of freedom-threatening instructions and monetary inducement on compliance. Canadian Journal of Behavioural Science 1971;3(4):408-12. [Google Scholar]
Doob 1973 {published data only}
- Doob AN, Freedman JL, Carlsmith JM. Effects of sponsor and prepayment on compliance with a mailed request. Journal of Applied Psychology 1973;57:346-7. [Google Scholar]
Doody 2003a {published data only}
- Doody MM, Sigurdson AS, Kampa D, Chimes K, Alexander BH, Ron E, et al. Randomized trial of financial incentives and delivery methods for improving response to a mailed questionnaire. American Journal of Epidemiology 2003;157(7):643-51. [DOI] [PubMed] [Google Scholar]
Doody 2003b {published data only}
- Doody MM, Sigurdson AS, Kampa D, Chimes K, Alexander BH, Ron E, et al. Randomized trial of financial incentives and delivery methods for improving response to a mailed questionnaire. American Journal of Epidemiology 2003;157(7):643-51. [DOI] [PubMed] [Google Scholar]
Dorman 1997 {unpublished data only}
- Dorman PJ, Slattery JM, Farrell B, Dennis MS, Sandercock PAG, the United Kingdom Collaborators in the International Stroke Trial. A randomised comparison of the EuroQol and SF-36 after stroke. BMJ 1997;315:461. [DOI] [PMC free article] [PubMed] [Google Scholar]
Downes‐Le Guin 2002 {published data only}
- Downes-Le Guin T, Janowitz P, Stone R, Khorram S. Use of pre-incentives in an Internet survey. Journal of Online Research 2002;www.ijor.org/ijor_archives/articles/Use_of_pre-incentives_in_an_internet_survey.pdf.
Drummond 2008 {published data only}
- Drummond FJ, Sharp L, Carsin AE, Kelleher T, Comber H. Questionnaire order significantly increased response to a postal survey sent to primary care physicians. Journal of Clinical Epidemiology 2008;61:177-85. [DOI] [PubMed] [Google Scholar]
Drummond 2014 {published data only}
- Drummond F J, O'Leary E, O'Neill C, Burns R, Sharp L. "Bird in the hand" cash was more effective than prize draws in increasing physician questionnaire response. JOURNAL OF CLINICAL EPIDEMIOLOGY 2014;67(2):228-31. [DOI] [PubMed] [Google Scholar]
Duffy 2001 {published data only}
- Duffy DL, Martin NG. Increasing the response rate to a mailed questionnaire by including more stamps on the return envelope: a cotwin control study. Twin Research 2001;4(2):71-2. [DOI] [PubMed] [Google Scholar]
Duhan 1990 {published data only}
- Duhan DF, Wilson RD. Prenotification and industrial survey responses. Industrial Marketing Management 1990;19:95-105. [Google Scholar]
Dunn 2003 {published data only}
- Dunn KM, Jordan K, Croft PR. Does questionnaire structure influence response in postal surveys? Journal of Clinical Epidemiology 2003;56:10–6. [DOI] [PubMed] [Google Scholar]
Dykema 2011 {published data only}
- Dykema Jennifer, Stevenson John, Day Brendan, Sellers Sherrill L, Bonham Vence L. Effects of incentives and prenotification on response rates and costs in a national web survey of physicians. Evaluation & the health professions 2011;34(4):434-47. [DOI] [PMC free article] [PubMed] [Google Scholar]
Dykema 2012 {published data only}
- Dykema J, Stevenson J, Kniss C, Kvale K, Gonzalez K, Cautley E. Use of Monetary and Nonmonetary Incentives to Increase Response Rates Among African Americans in the Wisconsin Pregnancy Risk Assessment Monitoring System. MATERNAL AND CHILD HEALTH JOURNAL 2012;16(4):785-91. [DOI] [PubMed] [Google Scholar]
Dykema 2013 {published data only}
- Dykema J, Stevenson J, Klein L, Kim Y, Day B. Effects of E-Mailed Versus Mailed Invitations and Incentives on Response Rates, Data Quality, and Costs in a Web Survey of University Faculty. SOCIAL SCIENCE COMPUTER REVIEW 2013;31(3):359-70. [Google Scholar]
Dykema 2015a {published data only}
- Dykema J, Jaques K, Cyffka K, Assad N, Hammers R G, Elver K, et al. EFFECTS OF SEQUENTIAL PREPAID INCENTIVES AND ENVELOPE MESSAGING IN MAIL SURVEYS. PUBLIC OPINION QUARTERLY 2015;79(4):906-31. [Google Scholar]
Dykema 2015b {published data only}
- Dykema J, Jaques K, Cyffka K, Assad N, Hammers R G, Elver K, et al. EFFECTS OF SEQUENTIAL PREPAID INCENTIVES AND ENVELOPE MESSAGING IN MAIL SURVEYS. PUBLIC OPINION QUARTERLY 2015;79(4):906-31. [Google Scholar]
Dykema 2021 {published data only}
- Dykema Jennifer, Stevenson John, Assad Nadia, Kniss Chad, Taylor Catherine A. Effects of Sequential Prepaid Incentives on Response Rates, Data Quality, Sample Representativeness, and Costs in a Mail Survey of Physicians. Evaluation & the health professions 2021;44(3):235-44. [DOI] [PMC free article] [PubMed] [Google Scholar]
Eaker 1998 {published data only}
- Eaker S, Bergstrom R, Bergstrom A, Hans-Olov A, Nyren O. Response rate to mailed epidemiologic questionnaires: a population-based randomized trial of variations in design and mailing routines. Americal Journal of Epidemiology 1998;147(1):74-82. [DOI] [PubMed] [Google Scholar]
Easton 1997 {published data only}
- Easton AN, Price JH, Telljohann SK, Boehm K. An informational versus monetary incentive in increasing physicians' response rates. Psychological Reports 1997;81:968-70. [DOI] [PubMed] [Google Scholar]
Edelman 2013 {published data only}
- Edelman L S, Yang R M, Guymon M, Olson L M. Survey Methods and Response Rates Among Rural Community Dwelling Older Adults. NURSING RESEARCH 2013;62(4):286-91. [DOI] [PubMed] [Google Scholar]
Edwards 2001 {unpublished data only}
- Edwards P, Roberts I. A comparison of two questionnaires for assessing outcome after head injury. unpublished.
Edwards 2009 {published data only}
- Edwards SL, Slattery ML, Edwards AM, Sweeney C, Murtaugh MA, Palmer LE, et al. Factors associated with response to a follow-up postal questionnaire in a cohort of American Indians. Preventive medicine 2009;48(6):596-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Edwards 2016a {published data only}
- Edwards L, Salisbury C, Horspool K, Foster A, Garner K, Montgomery AA. Increasing follow-up questionnaire response rates in a randomized controlled trial of telehealth for depression: three embedded controlled studies. TRIALS 2016;17(1):107. [DOI] [PMC free article] [PubMed] [Google Scholar]
Edwards 2016b {published data only}
- Edwards L, Salisbury C, Horspool K, Foster A, Garner K, Montgomery AA. Increasing follow-up questionnaire response rates in a randomized controlled trial of telehealth for depression: three embedded controlled studies. TRIALS 2016;17(1):107. [DOI] [PMC free article] [PubMed] [Google Scholar]
Edwards 2016c {published data only}
- Edwards L, Salisbury C, Horspool K, Foster A, Garner K, Montgomery AA. Increasing follow-up questionnaire response rates in a randomized controlled trial of telehealth for depression: three embedded controlled studies. TRIALS 2016;17(1):107. [DOI] [PMC free article] [PubMed] [Google Scholar]
Elkind 1986 {published data only}
- Elkind M, Tryon GS, De Vito AJ. Effects of type of postage and covering envelope on response rates in a mail survey. Psychological Reports 1986;59:279-83. [Google Scholar]
Enger 1993 {unpublished data only}
- Enger JM. Survey questionnaire format effect on response rate and cost per return. Paper presented at the Annual Meeting of the American Educational Research Association, Atlanta 1993.
Erdogan 2002 {published data only}
- Erdogan BZ, Baker MJ. Increasing mail survey response rates from an industrial population: a cost-effectiveness analysis of four follow-up techniques. Industrial Marketing Management 2002;31:65-73. [Google Scholar]
Ernst 2018 {published data only}
- Ernst S A, Brand T, Lhachimi S K, Zeeb H. Combining Internet-Based and Postal Survey Methods in a Survey among Gynecologists: Results of a Randomized Trial. HEALTH SERVICES RESEARCH 2018;53(2):879-95. [DOI] [PMC free article] [PubMed] [Google Scholar]
Etter 1996 {published data only}
- Etter J-F, Perneger TV, Rougemont A. Does sponsorship matter in patient satisfaction surveys? A randomized trial. Medical Care 1996;34(4):327-35. [DOI] [PubMed] [Google Scholar]
Etter 1998a {published data only}
- Etter J-F, Perneger TV, Ronchi A. Collecting saliva samples by mail. American Journal of Epidemiology 1998;147(2):141-6. [DOI] [PubMed] [Google Scholar]
Etter 1998b {published data only}
- Etter J-F, Perneger TV, Laporte J-D. Unexpected effects of a prior feedback letter and a professional layout on the response rate to a mail survey in Geneva. Journal of Epidemiology and Community Health 1998;52:128-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Etter 2002 {published data only}
- Etter JF, Cucherat M, Perneger TV. Questionnaire color and response patterns in mailed surveys: a randomised trial and meta-analysis. Evaluation and the Health Professions 2002;25(2):185-99. [DOI] [PubMed] [Google Scholar]
Etzel 1974 {published data only}
- Etzel MJ, Walker BJ. Effects of alternative follow-up procedures on mail survey response rates. Journal of Applied Psychology 1974;59(2):219-21. [Google Scholar]
Evans 2004 {published data only}
- Evans BR, Peterson BL, Demark-Wahnefried W. No difference in response rate to a mailed survey among prostate cancer survivors using conditional versus unconditional incentives. Cancer Epidemiology, Biomarkers & Prevention 2004;13(2):277-8. [DOI] [PubMed] [Google Scholar]
Falthzik 1971 {published data only}
- Falthzik AM, Carroll SJ. Rate of return for closed versus open-ended questions in a mail questionnaire survey of industrial organizations. Psychological Reports 1971;29:1121-2. [Google Scholar]
Faria 1990 {published data only}
- Faria AJ, Dickinson JR, Filipic TV. The effect of telephone versus letter prenotification on mail survey response rate, speed, quality and cost. Journal of the Market Research Society 1990;32(4):551-68. [Google Scholar]
Faria 1992 {published data only}
- Faria AJ, Dickinson JR. Mail survey response, speed, and cost. Industrial Marketing Management 1992;21:51-60. [Google Scholar]
Faria 1997 {published data only}
- Faria MC, Mateus CL, Coelho F, Martins R, Barros H. Postal questionnaires: a useful strategy for the follow up of stroke cases? [Uma Estrategia util para o seguimento de doentes com Acidente Vascular Cerebral?]. Acta Medica Portugesa 1997;10:61-5. [PubMed] [Google Scholar]
Farley 2014 {published data only}
- Farley K, Hanbury A, Thompson C. Gathering opinion leader data for a tailored implementation intervention in secondary healthcare: a randomised trial. BMC MEDICAL RESEARCH METHODOLOGY 2014;14:38. [DOI] [PMC free article] [PubMed] [Google Scholar]
Farmer 2005 {published data only}
- Farmer A J, Doll H A. In a randomized trial, outcomes were not affected by intensive follow-up over 1 year. JOURNAL OF CLINICAL EPIDEMIOLOGY 2005;58(10):991-6. [DOI] [PubMed] [Google Scholar]
Feigelson 2017 {published data only}
- Feigelson Heather Spencer, McMullen Carmit K, Madrid Sarah, Sterrett Andrew T, Powers J David, Blum-Barnett Erica, et al. Optimizing patient-reported outcome and risk factor reporting from cancer survivors: a randomized trial of four different survey methods among colorectal cancer survivors. Journal of cancer survivorship : research and practice 2017;11(3):393-400. [DOI] [PMC free article] [PubMed] [Google Scholar]
Feild 1975 {published data only}
- Feild HS. Effects of sex of investigator on mail survey response rates and response bias. Journal of Applied Psychology 1975;60(6):772-3. [Google Scholar]
Felix 2011 {published data only}
- Felix L M, Burchett H E, Edwards P J. Factorial trial found mixed evidence of effects of pre-notification and pleading on response to Web-based survey. JOURNAL OF CLINICAL EPIDEMIOLOGY 2011;64(5):531-6. [DOI] [PubMed] [Google Scholar]
Ferrell 1984 {published data only}
- Ferrell OC, Childers TL, Reukert RW. Effects of situational factors on mail survey response. Educators' Conference Proceedings 1984;1:364-7. [Google Scholar]
Finn 1983 {published data only}
- Finn DW. Response speeds, functions, and predictability in mail surveys. Journal of the Academy of Marketing Science 1983;11(2):61-70. [Google Scholar]
Finsen 2006 {published data only}
- Finsen V, Storeheier AH. Scratch lottery tickets are a poor incentive to respond to mailed questionnaires. BMC Medical Research Methodology 2006;6(19):1-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Fiset 1994 {published data only}
- Fiset L, Milgrom P, Tarnai J. Dentists' response to financial incentives in a mail survey of malpractice liability experience. Journal of Public Health Dentistry 1994;54(2):68-72. [DOI] [PubMed] [Google Scholar]
Fluss 2014 {published data only}
- Fluss E, Bond C M, Jones G T, Macfarlane G J. The effect of an internet option and single-sided printing format to increase the response rate to a population-based study: a randomized controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2014;9(14):104. [DOI] [PMC free article] [PubMed] [Google Scholar]
Ford 1967a {published data only}
- Ford NM. The advance letter in mail surveys. Journal of Marketing Research 1967;4:202-4. [Google Scholar]
Ford 1967b {published data only}
- Ford NM. The advance letter in mail surveys. Journal of Marketing Research 1967;4:202-4. [Google Scholar]
Ford 1968 {published data only}
- Ford NM. Questionnaire appearance and response rates in mail surveys. Journal of Advertising Research 1968;8(3):43-5. [Google Scholar]
Foushee 1990 {published data only}
- Foushee KD, McLellan RW. The effect of the timing of follow-up on response rates to international surveys. International Journal of Hospitality Management 1990;9(1):21-5. [Google Scholar]
Fowler 2019 {published data only}
- Fowler Floyd J Jr, Cosenza Carol, Cripps Lauren A, Edgman-Levitan Susan, Cleary Paul D. The effect of administration mode on CAHPS survey response rates and results: A comparison of mail and web-based approaches. Health services research 2019;54(3):714-21. [DOI] [PMC free article] [PubMed] [Google Scholar]
Frederiks 2020 {published data only}
- Frederiks E R, Romanach L M, Berry A, Toscas P. Making energy surveys more impactful: Testing material and non-monetary response strategies. ENERGY RESEARCH & SOCIAL SCIENCE 2020;63:101409. [Google Scholar]
Fredrickson 2005 {published data only}
- Fredrickson D D, Jones T L, Molgaard C A, Carman C G, Schukman J, Dismuke S E, et al. Optimal design features for surveying low-income populations. JOURNAL OF HEALTH CARE FOR THE POOR AND UNDERSERVED 2005;16(4):677-90. [DOI] [PubMed] [Google Scholar]
Freise 2001 {published data only}
- Freise DC, Scheibler F, Pfaff H. Der zusammenhang zwischen fragebogenlange und der hohe des rucklaufs bei patientenbefragungen [Correlation between questionnaire length and response rate in patient surveys]. Gesundheitswesen 2001;63:A13. [Google Scholar]
Friedman 1975 {published data only}
- Friedman HH, Goldstein L. Effect of ethnicity of signature on the rate of return and content of a mail questionnaire. Journal of Applied Psychology 1975;60(6):770-1. [Google Scholar]
Friedman 1979 {published data only}
- Friedman HH, San Augustine AJ. The effects of a monetary incentive and the ethnicity of the sponsors signature on the rate and quality of response to a mail survey. Journal of the Academy of Marketing Science 1979;7(2):95-101. [Google Scholar]
Furse 1982 {published data only}
- Furse DH, Stewart DW. Monetary incentives versus promised contribution to charity: new evidence on mail survey response. Journal of Marketing Research 1982;XIX:375-80. [Google Scholar]
Furst 1979 {published and unpublished data}
- Furst LG, Blitchington WP. The use of a descriptive cover letter and secretary pre-letter to increase response rate in a mailed survey. Personnel Psychology 1979;32:155-9. [Google Scholar]
Futrell 1977 {published data only}
- Futrell CM, Swan J. Anonymity and response by salespeople to a mail questionnaire. Journal of Marketing Research 1977;14:611-6. [Google Scholar]
Futrell 1978 {published data only}
- Futrell CM, Stem DE, Fortune BD. Effects of signed versus unsigned internally administered questionnaires for managers. Journal of Business Research 1978;6:91-8. [Google Scholar]
Futrell 1981 {published data only}
- Futrell CM, Lamb C. Effect on mail survey return rates of including questionnaires with follow up letters. Perceptual and Motor Skills 1981;52:11-5. [Google Scholar]
Futrell 1982 {published data only}
- Futrell CM, Hise RT. The effects of anonymity and a same-day deadline on the response rate to mail surveys. European Research 1982;10:171-5. [Google Scholar]
Gajic 2012 {published data only}
- Gajic Aleksandra, Cameron David, Hurley Jeremiah. The cost-effectiveness of cash versus lottery incentives for a web-based, stated-preference community survey. The European Journal of Health Economics 2012;13(6):789-99. [DOI] [PubMed] [Google Scholar]
Gajraj 1990 {published data only}
- Gajraj AM, Faria AJ, Dickinson JR. A comparison of the effect of promised and provided lotteries, monetary and gift incentives on mail survey response rate, speed and cost. Journal of the Market Research Society 1990;32(1):141-62. [Google Scholar]
Galesic 2009 {published data only}
- Galesic Mirta, Bosnjak Michael. Effects of Questionnaire Length on Participation and Indicators of Response Quality in a Web Survey. PUBLIC OPINION QUARTERLY 2009;73(2):349-60. [Google Scholar]
Garcia 2014 {published data only}
- Garcia Ivett, Portugal Cecilia, Chu Li-Hao, Kawatkar Aniket A. Response rates of three modes of survey administration and survey preferences of rheumatoid arthritis patients. Arthritis care & research 2014;66(3):364-70. [DOI] [PubMed] [Google Scholar]
Gaski 2004a {published data only}
- Gaski JF. Efficacy of a particular mail survey appeal: does it help to disclose that the purpose is a dissertation? Perceptual & Motor Skills 2004a;99(3 Pt 2):1295-8. [DOI] [PubMed] [Google Scholar]
Gaski 2004b {published data only}
- Gaski JF. Efficacy of a particular mail survey appeal: does it help to disclose that the purpose is a dissertation? Perceptual & Motor Skills 2004b;99(3 Pt 2):1295-8. [DOI] [PubMed] [Google Scholar]
Gates 2009 {published data only}
- Gates Simon, Williams Mark A, Withers Emma, Williamson Esther, Mt-Isa Shahrul, Lamb Sarah E. Does a monetary incentive improve the response to a postal questionnaire in a randomised controlled trial? The MINT incentive study. Trials 2009;10(101263253):44. [DOI] [PMC free article] [PubMed] [Google Scholar]
Gattellari 2001 {published data only}
- Gattellari M, Ward JE. Will donations to their learned college increase surgeons' participation in surveys? A randomized trial. Journal of Clinical Epidemiology 2001;54:645-50. [DOI] [PubMed] [Google Scholar]
Gattellari 2004 {published data only}
- Gattellari M, Ward JE. Does a deadline improve men’s participation in self-administered health surveys? A randomized controlled trial in general practice. Journal of Public Health 2004;26(4):384-7. [DOI] [PubMed] [Google Scholar]
Gattellari 2012 {published data only}
- Gattellari M, Zwar N, Worthington J M. No difference demonstrated between faxed or mailed prenotification in promoting questionnaire response among family physicians: a randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2012;65(5):544-52. [DOI] [PubMed] [Google Scholar]
Gendall 1996 {published data only}
- Gendall P. The effect of questionnaire cover design in mail surveys. Marketing Bulletin 1996;7:30-8. [Google Scholar]
Gendall 1998 {published data only}
- Gendall P, Hoek J, Brennan M. The tea bag experiment: more evidence on incentives in mail surveys. Journal of the Market Research Society 1998;40(4):347-51. [Google Scholar]
Gendall 2005a {published data only}
- Gendall P. The effect of covering letter personalisation in mail surveys. International Journal of Market Research 2005a;47(4):376-82. [Google Scholar]
Gendall 2005b {published data only}
- Gendall P. Can you judge a questionnaire by its cover? The effect of questionnaire cover design on mail survey response. International Journal of Public Opinion Research 2005b;17(3):346-61. [Google Scholar]
Gendall 2005c {published data only}
- Gendall P, Leong M, Healey B. The effect of prepaid non-monetary incentives in mail surveys. ANZMAC 2005 Conference: Marketing Research and Research Methodologies (quantitative) 2005;1:21-7. [Google Scholar]
Gendall 2008 {published data only}
- Gendall P, Healey B. Alternatives to Prepaid Monetary Incentives in Mail Surveys. International Journal of Public Opinion Research 2008;20(4):517–527. [Google Scholar]
Gibson 1999a {published data only}
- Gibson PJ, Koepsell TD, Diehr P, Hale C. Increasing response rates for mailed surveys of medicaid clients and other low-income populations. American Journal of Epidemiology 1999;149(11):1057-62. [DOI] [PubMed] [Google Scholar]
Gibson 1999b {published data only}
- Gibson PJ, Koepsell TD, Diehr P, Hale C. Increasing response rates for mailed surveys of medicaid clients and other low-income populations. American Journal of Epidemiology 1999;149(11):1057-62. [DOI] [PubMed] [Google Scholar]
Gibson 1999c {published data only}
- Gibson PJ, Koepsell TD, Diehr P, Hale C. Increasing response rates for mailed surveys of medicaid clients and other low-income populations. American Journal of Epidemiology 1999;149(11):1057-62. [DOI] [PubMed] [Google Scholar]
Giles 1978 {published data only}
- Giles WF, Feild HS. Effects of amount, format, and location of demographic information on questionnaire return rate and response bias of sensitive and non sensitive items. Personnel Psychology 1978;31:549-59. [Google Scholar]
Gillpatrick 1994 {published and unpublished data}
- Gillpatrick TR, Harmon RR, Tseng LP. The effect of a nominal monetary gift and different contacting approaches on mail survey response among engineers. IEE Transactions of Engineering Management 1994;41:285-90. [Google Scholar]
Gitelson 1992 {published data only}
- Gitelson RJ, Drogin EB. An experiment on the efficacy of a certified final mailing. Journal of Leisure Research 1992;24(1):72-8. [Google Scholar]
Gjostein 2016 {published data only}
- Gjostein D K, Huitfeldt A, Loberg M, Adami H O, Garborg K, Kalager M, et al. Incentives and participation in a medical survey. TIDSSKRIFT FOR DEN NORSKE LAEGEFORENING 2016;136(12-13):1082-7. [DOI] [PubMed] [Google Scholar]
Glidewell 2012a {published data only}
- Glidewell, L, Thomas, R, MacLennan, G, et al. Do incentives, reminders or reduced burden improve healthcare professional response rates in postal questionnaires? two randomised controlled trials. BMC HEALTH SERVICES RESEARCH 2012;14(12):250. [DOI] [PMC free article] [PubMed] [Google Scholar]
Glidewell 2012b {published data only}
- Glidewell, L, Thomas, R, MacLennan, G, et al. Do incentives, reminders or reduced burden improve healthcare professional response rates in postal questionnaires? two randomised controlled trials. BMC HEALTH SERVICES RESEARCH 2012;14(12):250. [DOI] [PMC free article] [PubMed] [Google Scholar]
Glisan 1982 {published data only}
- Glisan G, Grimm JL. Improving response rate in an industrial setting: will traditional variables work? Southern Marketing Association Proc 1982;20:265-8. [Google Scholar]
Godwin 1979 {published data only}
- Godwin K. The consequences of large monetary incentives in mail surveys of elites. Public Opinion Quarterly 1979;43:378-87. [Google Scholar]
Goldstein 1975 {published data only}
- Goldstein L, Friedman HH. A case for double postcards in surveys. J Advertising Research 1975;15:43-7. [Google Scholar]
Goodstadt 1977 {published data only}
- Goodstadt MS, Chung L, Kronitz R, Cook G. Mail survey response rates: their manipulation and impact. Journal of Marketing Research 1977;14:391-5. [Google Scholar]
Goodwin 2020 {published data only}
- Goodwin M, Walsh T, Whittaker W, Emsley R, Sutton M, Tickle M, et al. Increasing questionnaire response: evidence from a nested RCT within a longitudinal birth cohort study. BMC MEDICAL RESEARCH METHODOLOGY 2020;20(1):163. [DOI] [PMC free article] [PubMed] [Google Scholar]
Göritz 2004a {published data only}
- Göritz AS. The impact of material incentives on response quantity, response quality,sample composition, survey outcome,and cost in online access panels. International Journal of Market Research 2004a;46(3):327-45. [Google Scholar]
Göritz 2004b {published data only}
- Göritz AS. The impact of material incentives on response quantity, response quality,sample composition, survey outcome, and cost in online access panels. International Journal of Market Research 2004b;46(3):327-45. [Google Scholar]
Goulao 2020a {published data only}
- Goulao B, Duncan A, Floate R, Clarkson J, Ramsay C. Three behavior change theory-informed randomized studies within a trial to improve response rates to trial postal questionnaires. JOURNAL OF CLINICAL EPIDEMIOLOGY 2020;122:35-41. [DOI] [PubMed] [Google Scholar]
Goulao 2020b {published data only}
- Goulao B, Duncan A, Floate R, Clarkson J, Ramsay C. Three behavior change theory-informed randomized studies within a trial to improve response rates to trial postal questionnaires. JOURNAL OF CLINICAL EPIDEMIOLOGY 2020;122:35-41. [DOI] [PubMed] [Google Scholar]
Goulao 2020c {published data only}
- Goulao B, Duncan A, Floate R, Clarkson J, Ramsay C. Three behavior change theory-informed randomized studies within a trial to improve response rates to trial postal questionnaires. JOURNAL OF CLINICAL EPIDEMIOLOGY 2020;122:35-41. [DOI] [PubMed] [Google Scholar]
Green 1986 {published data only}
- Green KE, Stager SF. The effects of personalization, sex, locale, and level taught on educators' responses to a mail survey. Journal of Experimental Education 1986;54:203-6. [Google Scholar]
Green 1989 {published data only}
- Green KE, Kvidahl RF. Personalization and offers of results: effects on response rates. Journal of Experimental Education 1989;57:263-70. [Google Scholar]
Green 2000 {published data only}
- Green RG, Murphy KD, Snyder SM. Should demographics be placed at the end or at the beginning of mailed questionnaires? An empirical answer to a persistent methodological question. Social Work Research 2000;24(4):237-40. [Google Scholar]
Greer 1994 {published data only}
- Greer TV, Lohtia R. Effects of source and paper color on response rates in mail surveys. Industrial Marketing Management 1994;23:47-54. [Google Scholar]
Griffin 2011 {published data only}
- Griffin, J M, Simon, A B, Hulbert, E, et al. A comparison of small monetary incentives to convert survey non-respondents: a randomized control trial. BMC MEDICAL RESEARCH METHODOLOGY 2011;11:81. [DOI] [PMC free article] [PubMed] [Google Scholar]
Griffith 1999 {published data only}
- Griffith LE, Cook DJ, Guyatt GH, Charles CA. Comparison of open and closed questionnaire formats in obtaining demographic information from Canadian general internists. Journal of Clinical Epidemiology 1999;52(10):997-1005. [DOI] [PubMed] [Google Scholar]
Groeneman 1986 {published data only}
- Groeneman S. People respond to surveys when the price is right. Marketing News 1986;19:29. [Google Scholar]
Groves 2000 {published data only}
- Groves BW, Olsson RH. Response rates to surveys with self-addressed, stamped envelopes versus a self-addressed label. Psychological Reports 2000;86:1226-8. [DOI] [PubMed] [Google Scholar]
Gueguen 2003a {published data only}
- Gueguen N, Legoherel P, Jacob C. Sollicitation de participation à une enquête par courriel:effet de la présence sociale et de l’attrait physique dudemandeur sur le taux de réponse. Revue canadienne des sciences du comportement 2003a;35(2):84-96. [Google Scholar]
Gueguen 2003b {published data only}
- Gueguen N, Legoherel P, Jacob C. Sollicitation de participation à une enquête par courriel:effet de la présence sociale et de l’attrait physique dudemandeur sur le taux de réponse. Revue canadienne des sciences du comportement, 2003b;35(2):84-96. [Google Scholar]
Gullahorn 1959 {published data only}
- Gullahorn JT, Gullahorn JE. Increasing returns from non-respondents. Public Opinion Quarterly 1959;23(1):119-21. [Google Scholar]
Gullahorn 1963 {published data only}
- Gullahorn JE, Gullahorn JT. An investigation of the effects of three factors on response to mail questionnaires. Public Opinion Quarterly 1963;27:294-6. [Google Scholar]
Guo 2016 {published data only}
- Guo Y M, Kopec J A, Cibere J, Li L C, Goldsmith C H. Population Survey Features and Response Rates: A Randomized Experiment. AMERICAN JOURNAL OF PUBLIC HEALTH 2016;106(8):1422-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
Gupta 1997 {published data only}
- Gupta L, Ward J, D'Este C. Differential effectiveness of telephone prompts by medical and nonmedical staff in increasing survey response rates: a randomised trial. Australian and New Zealand Journal of Public Health 1997;21(1):98-9. [DOI] [PubMed] [Google Scholar]
Hackler 1973 {published data only}
- Hackler JC, Bourgette P. Dollars, dissonance and survey returns. Public Opinion Quarterly 1973;37:276-81. [Google Scholar]
Hall 2013 {published data only}
- Hall A E, Sanson-Fisher R W, Lynagh M C, Threlfall T, D'Este C A. Format and readability of an enhanced invitation letter did not affect participation rates in a cancer registry-based study: a randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2013;66(1):85-94. [DOI] [PubMed] [Google Scholar]
Hall 2019 {published data only}
- Hall Eric, Sanchez Travis, Stephenson Rob, Stein Aryeh D, Sineath Robert Craig, Zlotorzynska Maria, et al. Randomised controlled trial of incentives to improve online survey completion among internet-using men who have sex with men. Journal of epidemiology and community health 2019;73(2):156-61. [DOI] [PMC free article] [PubMed] [Google Scholar]
Halpern 2002 {published data only}
- Halpern SD, Ubel PA, Berlin JA, Asch DA. Randomized trial of $5 versus $10 monetary incentives, envelope size, and candy to increase physician response rates to mailed questionnaires. Medical Care 2002;40(9):834-9. [DOI] [PubMed] [Google Scholar]
Halpern 2011a {published data only}
- Halpern Scott D, Kohn Rachel, Dornbrand-Lo Aaron, Metkus Thomas, Asch David A, Volpp Kevin G. Lottery-based versus fixed incentives to increase clinicians' response to surveys. Health services research 2011;46(5):1663-74. [DOI] [PMC free article] [PubMed] [Google Scholar]
Halpern 2011b {published data only}
- Halpern Scott D, Kohn Rachel, Dornbrand-Lo Aaron, Metkus Thomas, Asch David A, Volpp Kevin G. Lottery-based versus fixed incentives to increase clinicians' response to surveys. Health services research 2011;46(5):1663-74. [DOI] [PMC free article] [PubMed] [Google Scholar]
Halpern 2011c {published data only}
- Halpern Scott D, Kohn Rachel, Dornbrand-Lo Aaron, Metkus Thomas, Asch David A, Volpp Kevin G. Lottery-based versus fixed incentives to increase clinicians' response to surveys. Health services research 2011;46(5):1663-74. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hammink 2010 {published data only}
- Hammink A, Giesen P, Wensing M. Pre-notification did not increase response rate in addition to follow-up: a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2010;63(11):1276-8. [DOI] [PubMed] [Google Scholar]
Han 2013 {published data only}
- Han Daifeng, Montaquila Jill M, Brick J Michael. An evaluation of incentive experiments in a two-phase address-based sample mail survey. Survey Research Methods 2013;7(3):207-18. [Google Scholar]
Hancock 1940 {published data only}
- Hancock JW. An experimental study of four methods of measuring unit costs of obtaining attitude toward the retail store. Journal of Applied Psychology 1940;24:213-30. [Google Scholar]
Hansen 1980a {published data only}
- Hansen RA, Robinson LM. Testing the effectiveness of alternative foot-in-the-door manipulations. Journal of Marketing Research 1980;17:359-64. [Google Scholar]
Hansen 1980b {published data only}
- Hansen RA. A self-perception interpretation of the effect of monetary and nonmonetary incentives on mail survey respondent behaviour. Journal of Marketing Research 1980;17:77-83. [Google Scholar]
Hardigan 2012 {published data only}
- Hardigan Patrick C, Succar Claudia Tammy, Fleisher Jay M. An analysis of response rate and economic costs between mail and web-based surveys among practicing dentists: a randomized trial. Journal of community health 2012;37(2):383-94. [DOI] [PubMed] [Google Scholar]
Hardigan 2016 {published data only}
- Hardigan Patrick C, Popovici Ioana, Carvajal Manuel J. Response rate, response time, and economic costs of survey research: A randomized trial of practicing pharmacists. Research in social & administrative pharmacy : RSAP 2016;12(1):141-8. [DOI] [PubMed] [Google Scholar]
Hardy 2016 {published data only}
- Hardy P, Bell J L, Brocklehurst P. Evaluation of the effects of an offer of a monetary incentive on the rate of questionnaire return during follow-up of a clinical trial: a randomised study within a trial. BMC MEDICAL RESEARCH METHODOLOGY 2016;16:82. [DOI] [PMC free article] [PubMed] [Google Scholar]
Harris 1978 {published data only}
- Harris JR, Guffey Jr HJ. Questionnaire returns: stamps versus business reply envelopes revisited. Journal of Marketing Research 1978;15:290-3. [Google Scholar]
Harris 2008 {published data only}
- Harris IA, Khoo OK, Young JM, Solomon MJ, Rae H. Lottery incentives did not improve response rate to a mailed survey: a randomized controlled trial. Journal of Clinical Epidemiology 2008;61(6):609-10. [DOI] [PubMed] [Google Scholar]
Harrison 2002 {published data only}
- Harrison RA, Holt D, Elton PJ. Do postage-stamps increase response rates to postal surveys? A randomized controlled trial. International Journal of Epidemiology 2002;31:872-4. [DOI] [PubMed] [Google Scholar]
Harrison 2004 {published data only}
- Harrison RA, Cock D. Increasing response to a postal survey of sedentary patients – a randomised controlled trial. BMC Health Services Research 2004;4(31):1-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Harvey 1986 {published data only}
- Harvey L. A research note on the impact of class-of-mail on response rates to mailed questionnaires. Journal of the Market Research Society 1986;28(3):299-300. [Google Scholar]
Hatch 2017 {published data only}
- Hatch R, Young D, Barber V, Harrison D A, Watkinson P. The effect of postal questionnaire burden on response rate and answer patterns following admission to intensive care: a randomised controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2017;17(1):49. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hathaway 2021a {published data only}
- Hathaway C A, Chavez M N, Kadono M, Ketcher D, Rollison D E, Siegel E M, et al. Improving Electronic Survey Response Rates Among Cancer Center Patients During the COVID-19 Pandemic: Mixed Methods Pilot Study. JMIR CANCER 2021;7(3):e30265. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hathaway 2021b {published data only}
- Hathaway C A, Chavez M N, Kadono M, Ketcher D, Rollison D E, Siegel E M, et al. Improving Electronic Survey Response Rates Among Cancer Center Patients During the COVID-19 Pandemic: Mixed Methods Pilot Study. JMIR CANCER 2021;7(3):e30265. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hathaway 2021c {published data only}
- Hathaway C A, Chavez M N, Kadono M, Ketcher D, Rollison D E, Siegel E M, et al. Improving Electronic Survey Response Rates Among Cancer Center Patients During the COVID-19 Pandemic: Mixed Methods Pilot Study. JMIR CANCER 2021;7(3):e30265. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hathaway 2021d {published data only}
- Hathaway C A, Chavez M N, Kadono M, Ketcher D, Rollison D E, Siegel E M, et al. Improving Electronic Survey Response Rates Among Cancer Center Patients During the COVID-19 Pandemic: Mixed Methods Pilot Study. JMIR CANCER 2021;7(3):e30265. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hauw‐Berlemont 2020 {published data only}
- Hauw-Berlemont Caroline, Serra Alexis, Groves Holden, Dzierba Amy, Louh Irene, Patel Mona, et al. The Source of the Message Matters: A Randomized Study Evaluating the Impact of a Survey Source on Response Rate. Annals of the American Thoracic Society 2020;17(4):525-7. [DOI] [PubMed] [Google Scholar]
Hawkins 1979 {published data only}
- Hawkins DI. The impact of sponsor identification and direct disclosure of respondent rights on the quantity and quality of mail survey data. Journal of Business 1979;52(4):577-90. [Google Scholar]
Hawley 2009 {published data only}
- Hawley Kristin M, Cook Jonathan R, Jensen-Doss Amanda. Do noncontingent incentives increase survey response rates among mental health providers? A randomized trial comparison. Administration and policy in mental health 2009;36(5):343-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
Heaton 1965 {published data only}
- Heaton E. Increasing mail questionnaire returns with a preliminary letter. Journal of Advertising Research 1965;5:36-9. [Google Scholar]
Heerwegh 2005a {published data only}
- Heerwegh D, Vanhove T, Matthijs K, Loosveldt G. The effect of personalizing on response rates and data quality in web surveys. International Journal of Social Research Methodology 2005a;8(2):85-99. [Google Scholar]
Heerwegh 2005b {published data only}
- Heerwegh D. Effects of personal salutations in e-mail invitations to participate in a web survey. Public Opinion Quarterly 2005b;69(4):588-98. [Google Scholar]
Heerwegh 2006 {published data only}
- Heerwegh D, Loosveldt G. Personalizing e-mail contacts: its influence on web survey response rate and social desirability response bias. International Journal of Public Opinion Research 2006;19(2):258-68. [Google Scholar]
Hendrick 1972 {published data only}
- Hendrick C, Borden R, Giesen M, Murray EJ, Seyfried BA. Effectiveness of ingratiation tactics in a cover letter on mail questionnaire response. Psychonomic Science 1972;26(6):349-51. [Google Scholar]
Hendriks 2001 {published data only}
- Hendriks AAJ, Vrielink MR, Smets EMA, Es SQ, Haes JCJM. Improving the assessment of (in)patients' satisfaction with hospital care. Medical Care 2001;39(3):270-83. [DOI] [PubMed] [Google Scholar]
Henley 1976 {published data only}
- Henley JR. Response rate to mail questionnaires with a return deadline. Public Opinion Quarterly 1976;40:374-5. [Google Scholar]
Hensley 1974 {published data only}
- Hensley WE. Increasing response rate by choice of postage stamp. Current Opinion Quarterly 1974;38:280-3. [Google Scholar]
Hewett 1974 {published data only}
- Hewett WC. How different combinations of postage on outgoing and return envelopes affect questionnaire returns. Journal of the Market Research Society 1974;16(1):49-50. [Google Scholar]
Hickey 2021 {published data only}
- Hickey Michael, McIntyre Lauralyn, Taljaard Monica, Abdulaziz Kasim, Yadav Krishan, Hickey Carly, et al. Effect of prenotification on the response rate of a postal survey of emergency physicians: a randomised, controlled, assessor-blind trial. BMJ open 2021;11(9):e052843. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hoffman 1998 {published data only}
- Hoffman SC, Burke AE, Helzlsouer KJ, Comstock GW. Controlled trial of the effect of length, incentives, and follow-up techniques on response to a mailed questionnaire. American Journal of Epidemiology 1998;148(10):1007-11. [DOI] [PubMed] [Google Scholar]
Hohwu 2013 {published data only}
- Hohwu L, Lyshol H, Gissler M, Jonsson S H, Petzold M, Obel C. Web-Based Versus Traditional Paper Questionnaires: A Mixed-Mode Survey With a Nordic Perspective. JOURNAL OF MEDICAL INTERNET RESEARCH 2013;15(8):e173. [DOI] [PMC free article] [PubMed] [Google Scholar]
Hopkins 1988 {published data only}
- Hopkins KD, Hopkins BR, Schon I. Mail surveys of professional populations: the effects of monetary gratuities on return rates. Journal of Experimental Education 1988;56:173-5. [Google Scholar]
Horn 2010 {published data only}
- Horn Rachel, Jones Steve, Warren Kate. The cost-effectiveness of postal and telephone methodologies in increasing routine outcome measurement response rates in CAMHS. Child and Adolescent Mental Health 2010;15(1):60-3. [DOI] [PubMed] [Google Scholar]
Hornik 1981 {published data only}
- Hornik J. Time cue and time perception effect on response to mail surveys. Journal of Marketing Research 1981;18:243-8. [Google Scholar]
Hornik 1982 {published data only}
- Hornik J. Impact of pre-call request form and gender interaction on response to a mail survey. Journal of Marketing Research 1982;19:144-51. [Google Scholar]
Horowitz 1974 {published data only}
- Horowitz JL, Sedlacek WE. Initial returns on mail questionnaires: a literature review and research note. Research in Higher Education 1974;2:361-7. [Google Scholar]
Houston 1975 {published data only}
- Houston MJ, Jefferson RW. The negative effects of personalization on response patterns in mail surveys. Journal of Marketing Research 1975;12:114-7. [Google Scholar]
Houston 1977 {published data only}
- Houston MJ, Nevin JR. The effect of source and appeal on mail survey response patterns. Journal of Marketing Research 1977;14:374-8. [Google Scholar]
Hubbard 1988a {published data only}
- Hubbard R, Little EL. Promised contributions to charity and mail survey responses: replication with extension. Public Opinion Quarterly 1988;52:223-30. [Google Scholar]
Hubbard 1988b {published data only}
- Hubbard R, Little EL. Cash prizes and mail survey response rates: a threshold analysis. Journal of the Academy of Marketing Science 1988;16(3&4):42-4. [Google Scholar]
Huck 1974 {published data only}
- Huck SW, Gleason E. Using monetary inducements to increase response rates from mailed surveys. Journal of Applied Psychology 1974;59(2):222-5. [Google Scholar]
Hyett 1977 {published data only}
- Hyett GP, Farr DJ. Postal questionnaires: double-sided printing compared with single-sided printing. European Research 1977;5:136-7. [Google Scholar]
Iglesias 2000 {published data only}
- Iglesias CP, Torgerson DJ. Does length of questionnaire matter? A randomised trial of response rates to a mailed questionnaire. Journal of Health Services Research and Policy 2000;5(2):19-21. [DOI] [PubMed] [Google Scholar]
Iglesias 2001 {published data only}
- Iglesias CP, Birks YF, Torgerson DJ. Improving the measurement of quality of life in older people: the York SF-12. Quarterly Journal of Medicine 2001;94:695-8. [DOI] [PubMed] [Google Scholar]
Iversen 2020 {published data only}
- Iversen Hilde Hestad, Holmboe Olaf, Bjertnaes Oyvind. Patient-reported experiences with general practitioners: a randomised study of mail and web-based approaches following a national survey. BMJ open 2020;10(10):e036533. [DOI] [PMC free article] [PubMed] [Google Scholar]
Jacob 2012 {published data only}
- Jacob Robin Tepper, Jacob Brian. Prenotification, Incentives, and Survey Modality: An Experimental Test of Methods to Increase Survey Response Rates of School Principals. Journal of Research on Educational Effectiveness 2012;5(4):401-18. [Google Scholar]
Jacobs 1986 {published data only}
- Jacobs LC. Effect of the use of optical scan sheets on survey response rate. Paper presented at the annual meeting of the American Educational Research Association 1986.
Jacoby 1990 {published data only}
- Jacoby A. Possible factors affecting response to postal questionnaires: findings from a study of general practitioner services. Journal of Public Health Medicine 1990;12(2):131-5. [DOI] [PubMed] [Google Scholar]
James 1990a {published data only}
- James J, Bolstein R. The effect of monetary incentives and follow-up mailings on the response rate and response quality in mail surveys. Public Opinion Quarterly 1990;54:346-61. [Google Scholar]
James 1990b {published data only}
- James J, Bolstein R. The effect of monetary incentives and follow-up mailings on the response rate and response quality in mail surveys. Public Opinion Quarterly 1990;54:346-61. [Google Scholar]
James 1992 {published data only}
- James J, Bolstein R. Large monetary incentives and their effect on mail survey response rates. Public Opinion Quarterly 1992;56:442-53. [Google Scholar]
James 2011 {published data only}
- James Katherine M, Ziegenfuss Jeanette Y, Tilburt Jon C, Harris Ann M, Beebe Timothy J. Getting physicians to respond: the impact of incentive type and timing on physician survey response rates. Health services research 2011;46(1 Pt 1):232-42. [DOI] [PMC free article] [PubMed] [Google Scholar]
James 2019 {published data only}
- James S, Parker A, Torgerson D. Pen and Social Incentive Letter Retention Study within a Trial (SWAT) - An embedded, factorial design randomised controlled trial to investigate whether the inclusion of a pen and/or social incentive text cover letter included with the 12-month postal que. TRIALS 2019;20(Suppl 1):P-183. [Google Scholar]
Jamtvedt 2008 {published data only}
- Jamtvedt G, Rosenbaum S, Dahm KT, Flottorp S. Chocolate bar as an incentive did not increase response rate among physiotherapists: a randomised controlled trial. BMC Research Notes 2008;1(34):1-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Jenkinson 2003 {published data only}
- Jenkinson C, Coulter A, Reeves R, Bruster S, Richards N. Properties of the Picker Patient Experience questionnaire in a randomized controlled trial of long versus short form survey instruments. Journal of Public Health Medicine 2003;25(3):197–201. [DOI] [PubMed] [Google Scholar]
Jensen 1994 {published data only}
- Jensen JL. The effect of survey format on response rate and patterns of response. Doctoral Dissertation 1994.
Jepson 2005a {published data only}
- Jepson C, Asch DA, Hershey JC, Ubel PA. In a mailed physician survey, questionnaire length had a threshold effect on response rate. Journal of Clinical Epidemiology 2005a;58(1):103-5. [DOI] [PubMed] [Google Scholar]
Jepson 2005b {published data only}
- Jepson C, Asch DA, Hershey JC, Ubel PA. In a mailed physician survey, questionnaire length had a threshold effect on response rate. Journal of Clinical Epidemiology 2005b;58(1):103-5. [DOI] [PubMed] [Google Scholar]
Jobber 1983 {published data only}
- Jobber D, Sanderson S. The effects of a prior letter and coloured questionnaire paper on mail survey response rates. Journal of the Market Research Society 1983;25(4):339-49. [Google Scholar]
Jobber 1985 {published data only}
- Jobber D, Sanderson S. The effect of two variables on industrial mail survey returns. Industrial Marketing Management 1985;14:119-21. [Google Scholar]
Jobber 1988 {published data only}
- Jobber D, Birro K, Sanderson SM. A factorial investigation of methods of stimulating response to mail surveys. European Journal of Operational Research 1988;37:158-64. [Google Scholar]
Jobber 1989 {published data only}
- Jobber D. An examination of the effects of questionnaire factors on response to an industrial mail survey. International Journal of Research in Marketing 1989;6:129-40. [Google Scholar]
Jobber D 1985 {published data only}
- Jobber D, Allen N, Oakland J. The impact of telephone notification strategies on response to an industrial mail survey. International Journal of Research Marketing 1985;2:291-8. [Google Scholar]
Johansson 1997a {published data only}
- Johansson L, Solvoll K, Opdahl S, Bjorneboe G-E, Drevon CA. Response rates with different distribution methods and reward, and reproducibility of a quantitative food frequency questionnaire. European Journal of Clinical Nutrition 1997;51:346-53. [DOI] [PubMed] [Google Scholar]
Johansson 1997b {published data only}
- Johansson L, Solvoll K, Opdahl S, Bjorneboe G-E, Drevon CA. Response rates with different distribution methods and reward, and reproducibility of a quantitative food frequency questionnaire. European Journal of Clinical Nutrition 1997;51:346-53. [DOI] [PubMed] [Google Scholar]
Johansson 1997c {published data only}
- Johansson L, Solvoll K, Opdahl S, Bjorneboe G-E, Drevon CA. Response rates with different distribution methods and reward, and reproducibility of a quantitative food frequency questionnaire. European Journal of Clinical Nutrition 1997;51:346-53. [DOI] [PubMed] [Google Scholar]
John 1994 {published data only}
- John EM, Savitz DA. Effect of a monetary incentive on response to a mail survey. Annals of Epidemiology 1994;4(3):231-5. [DOI] [PubMed] [Google Scholar]
Joinson 2005a {published data only}
- Joinson AN, Reips UD. Personalized salutation, power of sender and response rates to Web-based surveys. Computers in Human Behavior 2005a;23(3):1-12. [Google Scholar]
Joinson 2005b {published data only}
- Joinson AN, Reips UD. Personalized salutation, power of sender and response rates to Web-based surveys. Computers in Human Behavior 2005b;23(3):1-10. [Google Scholar]
Joinson 2005c {published data only}
- Joinson AN, Reips UD. Personalized salutation, power of sender and response rates to Web-based surveys. Computers in Human Behavior 2005;23(3):1-10. [Google Scholar]
Joinson 2007a {published data only}
- Joinson AN, Woodley A, Reips UD. Personalization, authentication and self-disclosure in self-administered Internet surveys. Computers in Human Behavior 2007a;23:275–85. [Google Scholar]
Joinson 2007b {published data only}
- Joinson AN, Woodley A, Reips UD. Personalization, authentication and self-disclosure in self-administered Internet surveys. Computers in Human Behavior 2007b;23:275–85. [Google Scholar]
Jones 1978 {published data only}
- Jones WH, Linda G. Multiple criteria effects in a mail survey experiment. Journal of Marketing Research 1978;15:280-4. [Google Scholar]
Jones 2000 {published data only}
- Jones R, Zhou M, Yates WR. Improving return rates for health-care outcome. Psychological Reports 2000;87:639-42. [DOI] [PubMed] [Google Scholar]
Junghans 2005 {published data only}
- Junghans C, Feder G, Hemingway H, Timmis A, Jones M. Recruiting patients to medical research: double blind randomised trial of "opt-in" versus "opt-out" strategies. BMJ 2005;331(940-):1-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Juszczak 2021 {published data only}
- Juszczak E, Hewer O, Partlett C, Hurd M, Bari V, Bowler U, et al. Evaluation of the effectiveness of an incentive strategy on the questionnaire response rate in parents of premature babies: a randomised controlled Study Within A Trial (SWAT) nested within SIFT. TRIALS 2021;22(1):554. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kahle 1978 {published data only}
- Kahle LR, Sales BD. Personalization of the outside envelope in mail surveys. Public Opinion Quarterly 1978;42:547-50. [Google Scholar]
Kalafatis 1995 {published data only}
- Kalafatis SP, Madden FJ. The effect of discount coupons and gifts on mail survey response rates among high involvement respondents. Journal of the Market Research Society 1995;37(2):171-84. [Google Scholar]
Kalantar 1999 {published data only}
- Kalantar JS, Talley NJ. The effects of lottery incentive and length of questionnaire on health survey response rates: a randomized study. Journal of Clinical Epidemiology 1999;52(11):1117–22. [DOI] [PubMed] [Google Scholar]
Kaplan 1970a {published data only}
- Kaplan S, Cole P. Factors affecting response to postal questionnaires. British Journal of Preventive and Social Medicine 1970a;24:245-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kaplan 1970b {published data only}
- Kaplan S, Cole P. Factors affecting response to postal questionnaires. British Journal of Preventive and Social Medicine 1970b;24:245-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kaplowitz 2004 {published data only}
- Kaplowitz MD, Lupi F. Color photographs and mail survey response rates. International Journal of Public Opinion Research 2004;16(2):199-206. [Google Scholar]
Kasprzyk 2001 {published data only}
- Kasprzyk D, Montano DE, St Lawrence JS, Phillips WR. The effects of variations in mode of delivery and monetary incentive on physicians' responses to a mailed survey assessing STD practice patterns. Evaluation and the Health Professions 2001;24(1):3-17. [DOI] [PubMed] [Google Scholar]
Kawash 1971 {published data only}
- Kawash MB, Aleamoni LM. Effect of a personal signature on the initial rate of return of a mailed questionnaire. Journal of Applied Psychology 1971;55(6):589-92. [Google Scholar]
Keating 2008 {published data only}
- Keating Nancy L, Zaslavsky Alan M, Goldstein Judy, West Dee W, Ayanian John Z. Randomized trial of $20 versus $50 incentives to increase physician survey response rates. Medical care 2008;46(8):878-81. [DOI] [PubMed] [Google Scholar]
Keding 2016a {published data only}
- Keding Ada, Brabyn Sally, MacPherson Hugh, Richmond Stewart J, Torgerson David J. Text message reminders to improve questionnaire response rates. Journal of clinical epidemiology 2016;79(jce, 8801383):90-5. [DOI] [PubMed] [Google Scholar]
Keding 2016b {published data only}
- Keding Ada, Brabyn Sally, MacPherson Hugh, Richmond Stewart J, Torgerson David J. Text message reminders to improve questionnaire response rates. Journal of clinical epidemiology 2016;79(jce, 8801383):90-5. [DOI] [PubMed] [Google Scholar]
Keding 2016c {published data only}
- Keding Ada, Brabyn Sally, MacPherson Hugh, Richmond Stewart J, Torgerson David J. Text message reminders to improve questionnaire response rates. Journal of clinical epidemiology 2016;79(jce, 8801383):90-5. [DOI] [PubMed] [Google Scholar]
Keeter 2001 {published data only}
- Keeter S, Kennamer JD, Ellis JM, Green RG. Does the use of colored paper improve response rate to mail surveys?: A multivariate experimental evaluation. Journal of Social Service Research 2001;28(1):69-78. [Google Scholar]
Kenyon 2005 {published data only}
- Kenyon S, Pike K, Jones D, Taylor D, Salt A, Marlow N, et al. The effect of a monetary incentive on return of a postal health and development questionnaire: a randomised trial. BMC Health Services Research 2005;5(55):1-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Keown 1985a {published data only}
- Keown CF. Foreign mail surveys: response rates using monetary incentives. Journal of International Business Studies 1985;16:151-3. [Google Scholar]
Keown 1985b {published data only}
- Keown CF. Foreign mail surveys: response rates using monetary incentives. Journal of International Business Studies 1985;16:151-3. [Google Scholar]
Kephart 1958 {published data only}
- Kephart WM, Bressler M. Increasing the response to mail questionnaires: a research study. Public Opinion Quarterly 1958;21:123-32. [Google Scholar]
Kereakoglow 2013 {published data only}
- Kereakoglow S, Gelman R, Partridge A H. Evaluating the effect of esthetically enhanced materials compared to standard materials on clinician response rates to a mailed survey. INTERNATIONAL JOURNAL OF SOCIAL RESEARCH METHODOLOGY 2013;16(4):301-6. [Google Scholar]
Kerin 1976 {published data only}
- Kerin RA, Harvey MG. Methodological considerations in corporate mail surveys: a research note. Journal of Business Research 1976;4(3):277-81. [Google Scholar]
Kerin 1981 {published data only}
- Kerin RA, Barry TE, Dubinsky AJ, Harvey MG. Offer of results and mail survey response from a commercial population: a test of Gouldner's Norm of Reciprocity. Proceeding of the American Institute of Decision Sciences 1981;1:283-5. [Google Scholar]
Kernan 1971 {published data only}
- Kernan JB. Are 'bulk rate occupants' really unresponsive? Public Opinion Quarterly 1971;35:420-2. [Google Scholar]
Khadjesari 2011a {published data only}
- Khadjesari Z, Murray E, Kalaitzaki E, White I R, McCambridge J, Thompson S G, et al. Impact and Costs of Incentives to Reduce Attrition in Online Trials: Two Randomized Controlled Trials. JOURNAL OF MEDICAL INTERNET RESEARCH 2011;13(1):e26. [DOI] [PMC free article] [PubMed] [Google Scholar]
Khadjesari 2011b {published data only}
- Khadjesari Z, Murray E, Kalaitzaki E, White I R, McCambridge J, Thompson S G, et al. Impact and Costs of Incentives to Reduce Attrition in Online Trials: Two Randomized Controlled Trials. JOURNAL OF MEDICAL INTERNET RESEARCH 2011;13(1):e26. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kilsdonk 2015 {published data only}
- Kilsdonk E, Dulmen-den Broeder E, Pal H J, Hollema N, Kremer L C, den Heuvel-Eibrink M M, et al. Effect of Web-Based Versus Paper-Based Questionnaires and Follow-Up Strategies on Participation Rates of Dutch Childhood Cancer Survivors: A Randomized Controlled Trial. JMIR CANCER 2015;1(2):e11. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kindra 1985 {published data only}
- Kindra GS, McGown KL, Bougie M. Stimulating responses to mailed questionnaires. An experimental study. International Journal of Research in Marketing 1985;2:219-35. [Google Scholar]
King 1978 {published data only}
- King JO. The influence of personalization on mail survey response rates. Arkansas Business and Economic Review 1978;11:15-8. [Google Scholar]
Koloski 2001 {published data only}
- Koloski NA, Talley NJ, Boyce PM, Morris-Yates AD. The effects of questionnaire length and lottery ticket inducement on the response rate in mail surveys. Psychology and Health 2001;16:67-75. [Google Scholar]
Koloski 2013 {published data only}
- Koloski N A, Jones M, Eslick G, Talley N J. Predictors of Response Rates to a Long Term Follow-Up Mail out Survey. PLOS ONE 2013;8(11):e79179. [DOI] [PMC free article] [PubMed] [Google Scholar]
Koo 1995 {published data only}
- Koo MM, Rohan TE. Printed signatures and response rates. Epidemiology 1995;6(5):568. [DOI] [PubMed] [Google Scholar]
Koo 1996 {published data only}
- Koo MM, Rohan TE. Types of advance notification in reminder letters and response rates. Epidemiology 1996;7(2):215-6. [DOI] [PubMed] [Google Scholar]
Kost 2018 {published data only}
- Kost Rhonda G, Correa Da Rosa Joel. Impact of survey length and compensation on validity, reliability, and sample characteristics for Ultrashort-, Short-, and Long-Research Participant Perception Surveys. Journal of Clinical and Translational Science 2018;2(1):31-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kropf 2005 {published data only}
- Kropf ME, Blair J. Eliciting survey cooperation: incentives, self-interest, and norms of cooperation. Evaluation Review 2005;29(6):559-75. [DOI] [PubMed] [Google Scholar]
Kurth 1987 {unpublished data only}
- Kurth LA. Message responses as functions of communication mode: a comparison of electronic mail and typed memoranda. Doctoral dissertation 1987.
Kuskowska‐Wolk 1992 {published data only}
- Kuskowska-Wolk A, Holte S, Ohlander EM, Bruce A, Holmberg L, Adami HO, et al. Effects of different designs and extension of a food frequency questionnaire on response rate, completeness of data and food frequency responses. International Journal of Epidemiology 1992;21(6):1144-50. [DOI] [PubMed] [Google Scholar]
Kypri 2003 {published data only}
- Kypri K, Gallagher SJ. Incentives to increase participation in an Internet survey of alcohol use: a controlled experiment. Alcohol & Alcoholism 2003;38(5):437-41. [DOI] [PubMed] [Google Scholar]
Kypri 2016 {published data only}
- Kypri K, Maclennan B, Connor J L. Effects of small incentives on survey response fractions: randomised comparisons in national alcohol surveys conducted in New Zealand. EUROPEAN JOURNAL OF PUBLIC HEALTH 2016;26(3):430-U12. [DOI] [PubMed] [Google Scholar]
Labarere 2000 {published data only}
- Labarere J, Francois P, Bertrand D, Fourny M, Olive F, Peyrin JC. Survey of inpatient satisfaction: comparison of different survey methods [Evaluation de la satisfaction des patients hospitalises: Comparaison de plusieurs methodes d'enquete]. La Presse Medicale 2000;29:1112-4. [PubMed] [Google Scholar]
Labrecque 1978 {published data only}
- Labrecque DP. A response rate experiment using mail questionnaires. Journal of Marketing 1978;42:82-3. [Google Scholar]
La Garce 1995 {published data only}
- La Garce R, Kuhn LD. The effect of visual stimuli on mail survey response rates. Industrial Marketing Management 1995;24:11-8. [Google Scholar]
Lagerros 2012 {published data only}
- Lagerros Y T, Sandin S, Bexelius C, Litton J E, Lof M. Estimating physical activity using a cell phone questionnaire sent by means of short message service (SMS): a randomized population-based study. EUROPEAN JOURNAL OF EPIDEMIOLOGY 2012;27(7):561-6. [DOI] [PubMed] [Google Scholar]
Langenderfer‐Magruder 2020 {published data only}
- Langenderfer-Magruder Lisa, Wilke Dina J. The Use of Text Message Reminders to Increase Completion of Web-Based Surveys: Results of Two Randomized Control Trials. Journal of Technology in Human Services 2020;38(1):22-37. [Google Scholar]
Lavelle 2008 {published data only}
- Lavelle K, Todd C, Campbell M. Do postage stamps versus pre-paid envelopes increase responses to patient mail surveys? A randomised controlled trial. BMC Health Services Research 2008;8(113):1-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Leece 2004 {published data only}
- Leece P, Bhandari M, Sprague S, Swiontkowski M F, Schemitsch E H, Tornetta P, et al. Internet versus mailed questionnaires: A randomized comparison (2). JOURNAL OF MEDICAL INTERNET RESEARCH 2004;6(3):26-33. [DOI] [PMC free article] [PubMed] [Google Scholar]
Leece 2006a {published data only}
- Leece P, Bhandari M, Sprague S, Swiontkowski MF, Schemitsch EH, Tornetta P. Does flattery work? A comparison of 2 different cover letters for an international survey of orthopedic surgeons. Canadian Journal of Surgery 2006a;49(2):90-5. [PMC free article] [PubMed] [Google Scholar]
Leece 2006b {published data only}
- Leece P, Bhandari M, Sprague S, Swiontkowski MF, Schemitsch EH, Tornetta P. Does flattery work? A comparison of 2 different cover letters for an international survey of orthopedic surgeons. Canadian Journal of Surgery 2006b;49(2):90-5. [PMC free article] [PubMed] [Google Scholar]
Leigh Brown 1997 {published data only}
- Leigh Brown AP, Lawrie HE, Kennedy AD, Webb JA, Torgerson DJ, Grant AM. Cost effectiveness of a prize draw on response to a postal questionnaire: results of a randomised trial among orthopaedic outpatients in Edinburgh. Journal of Epidemiology and Community Health 1997;51:463-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Leung 2002 {published data only}
- Leung GM, Ho LM, Chan MF, Johnston JM, Wong FK. The effects of cash and lottery incentives on mailed surveys to physicians: a randomized trial. Journal of Clinical Epidemiology 2002;55:801-7. [DOI] [PubMed] [Google Scholar]
Leung 2004 {published data only}
- Leung GM, Johnston JM, Saing H, Tin KY, Wong IO, Ho, LM. Prepayment was superior to postpayment cash incentives in a randomized postal survey among physicians. Journal of Clinical Epidemiology 2004;57(8):777-84. [DOI] [PubMed] [Google Scholar]
Levy 2012 {published data only}
- Levy R M, Shapiro M, Halpern S D, Ming M E. Effect of Personalization and Candy Incentive on Response Rates for a Mailed Survey of Dermatologists. JOURNAL OF INVESTIGATIVE DERMATOLOGY 2012;132(3):724-6. [DOI] [PubMed] [Google Scholar]
Lewis 2017 {published data only}
- Lewis H, Keding A, Bosanquet K, Gilbody S, Torgerson D. An randomized controlled trial of Post-it® notes did not increase postal response rates in older depressed participants. Journal of Evaluation in Clinical Practice 2017;23(1):102-7. [DOI] [PubMed] [Google Scholar]
Lewis 2017a {published data only}
- Lewis T, Hess K. The Effect of Alternative E-mail Contact Timing Strategies on Response Rates in a Self-administered Web Survey. Field Methods 2017;29(4):351-64. [Google Scholar]
Linsky 1965 {published data only}
- Linsky AS. A factorial experiment in inducing responses to a mail questionnaire. Sociology and Social Research 1965;49:183-9. [Google Scholar]
Little 1990 {published data only}
- Little EL, Engelbrecht EG. The use of incentives to increase mail survey response rates in a business environment. Journal of Direct Marketing 1990;4(4):46-9. [Google Scholar]
Loban 2017 {published data only}
- Loban A, Mandefield L, Hind D, Bradburn M. A randomized trial found online questionnaires supplemented by postal reminders generated a cost-effective and generalizable sample but don't forget the reminders. Journal of Clinical Epidemiology 2017;92:116-25. [DOI] [PubMed] [Google Scholar]
London 1990a {published data only}
- London SJ, Dommeyer CJ. Increasing response to industrial mail surveys. Industrial Marketing Management 1990;19:235-41. [Google Scholar]
London 1990b {published data only}
- London SJ, Dommeyer CJ. Increasing response to industrial mail surveys. Industrial Marketing Management 1990;19:235-41. [Google Scholar]
Lorenzi 1988 {published data only}
- Lorenzi P, Friedman R, Paolollo JGP. Consumer mail survey responses: more (unbiased) bang for the buck. Journal of Consumer Marketing 1988;5(4):31-40. [Google Scholar]
Lund 1998 {published data only}
- Lund E, Gram IT. Response rate according to title and length of questionnaire. Scandinavian Journal of Social Medicine 1998;26(2):154-60. [DOI] [PubMed] [Google Scholar]
Lusinchi 2007 {published data only}
- Lusinchi D. Increasing response rates & data quality of Web surveys: Pre-notification and questionnaire paging format. https://nces.ed.gov/FCSM/pdf/2007FCSM_Lusinchi-X-A.pdf 2007.
MacLennan 2013 {published data only}
- MacLennan Graeme, McDonald Alison, McPherson Gladys, Avenell Alison. Do advance telephone calls ahead of reminder questionnaires increase response rate in non-responders compared to questionnaire reminders only: The record phone trial. Clinical Trials 2013;10(SUPPL. 2):S1. [DOI] [PMC free article] [PubMed] [Google Scholar]
Maheux 1989a {published data only}
- Maheux B, Legault C, Lambert J. Increasing response rates in physicians' mail surveys: an experimental study. American Journal of Public Health 1989;79(5):638-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Maheux 1989b {published data only}
- Maheux B, Legault C, Lambert J. Increasing response rates in physicians' mail surveys: an experimental study. American Journal of Public Health 1979;79(5):638-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Mallen 2008 {unpublished data only}
- Mallen C, Dunn KM, Thomas E, Peat G. Thicker paper and larger font increased response and completeness in a postal survey. Journal of Clinical Epidemiology 2008;61(12):1296-300. [DOI] [PubMed] [Google Scholar]
Man 2011 {published data only}
- Man M S, Tilbrook H E, Jayakody S, Hewitt C E, Cox H, Cross B, et al. Electronic reminders did not improve postal questionnaire response rates or response times: a randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2011;64(9):1001-4. [DOI] [PubMed] [Google Scholar]
Mann 2005 {published data only}
- Mann CB. Do advance letters improve preelection forecast accuracy? Public Opinion Quarterly 2005;69(4):561-71. [Google Scholar]
Mann 2008 {published data only}
- Mann S L, Lynn D J, Peterson A V. The "Downstream" effect of token prepaid cash incentives to parents on their young adult children's survey participation. PUBLIC OPINION QUARTERLY 2008;72(3):487-501. [Google Scholar]
Marcus 2007 {published data only}
- Marcus B, Bosnjak M, Lindner S, Pilischenko S, Schütz A. Compensating for low topic interest and long surveys. A field experiment on nonresponse in web surveys. Social Science Computer Review 2007;25:372-83. [Google Scholar]
Marrett 1992 {published data only}
- Marrett LD, Kreiger N, Dodds L, Hilditch S. The effect on response rates of offering a small incentive with a mailed questionnaire. AEP 1992;2(5):745-53. [DOI] [PubMed] [Google Scholar]
Marsh 1999 {published data only}
- Marsh P, Kendrick D. Using a diary to record near misses and minor injuries - which method of administration is best? Injury Prevention 1999;5:305-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Martin 1970 {published data only}
- Martin JD, McConnell JP. Mail questionnaire response induction: the effect of four variables on the response of a random sample to a difficult questionnaire. Social Science Quarterly 1970;51:409-14. [Google Scholar]
Martin 1989 {published data only}
- Martin WS, Duncan WJ, Powers TL, Sawyer JC. Costs and benefits of selected response inducement techniques in mail survey research. Journal of Business Research 1989;19:67-79. [Google Scholar]
Martin 1994 {published data only}
- Martin CL. The impact of topic interest on mail survey response behaviour. Journal of the Market Research Society 1994;36(4):327-38. [Google Scholar]
Martinson 2000 {published data only}
- Martinson BC, Lazovich D, Lando HA, Perry CL, McGovern PG, Boyle RG. Effectiveness of monetary incentives for recruiting adolescents to an intervention trial to reduce smoking. Preventive Medicine 2000;31:706-13. [DOI] [PubMed] [Google Scholar]
Mason 1961 {published data only}
- Mason WS, Dressel RJ, Bain RK. An experimental study of factors affecting response to a mail survey of beginning teachers. Public Opinion Quarterly 1961;25:296-9. [Google Scholar]
Matteson 1974 {published data only}
- Matteson MT. Type of transmittal letter and questionnaire colour as two variables influencing response rates in a mail survey. Journal of Applied Psychology 1974;59(4):535-6. [Google Scholar]
Mauz 2018 {published data only}
- Mauz Elvira, Hoffmann Robert, Houben Robin, Krause Laura, Kamtsiuris Panagiotis, Goswald Antje. Mode Equivalence of Health Indicators Between Data Collection Modes and Mixed-Mode Survey Designs in Population-Based Health Interview Surveys for Children and Adolescents: Methodological Study. Journal of medical Internet research 2018;20(3):e64. [DOI] [PMC free article] [PubMed] [Google Scholar]
Maxwell 2009 {published data only}
- Maxwell A E, Bastani R, Glenn B A, Mojica C M, Chang L C. An Experimental Test of the Effect of Incentives on Recruitment of Ethnically Diverse Colorectal Cancer Cases and Their First-Degree Relatives into a Research Study. CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION 2009;18(10):2620-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
McCaffery 2019 {published data only}
- McCaffery J, Mitchell A S, Fairhurst C, Cockayne S, Rodgers S, Relton C, et al. Does handwriting the name of a potential trial participant on an invitation letter improve recruitment rates? A randomised controlled study within a trial. F1000Research 2019;8:659. [DOI] [PMC free article] [PubMed] [Google Scholar]
McCambridge 2011 {published data only}
- McCambridge J, Kalaitzaki E, White I R, Khadjesari Z, Murray E, Linke S, et al. Impact of Length or Relevance of Questionnaires on Attrition in Online Trials: Randomized Controlled Trial. JOURNAL OF MEDICAL INTERNET RESEARCH 2011;13(4):e96. [DOI] [PMC free article] [PubMed] [Google Scholar]
McColl 2003a {published data only}
- McColl E, Eccles MP, Rousseau NS, Steen IN, Parkin DW, Grimshaw JM. From the generic to the condition-specific? Instrument order effects in quality of life assessment. Medical Care 2003a;7:777–90. [DOI] [PubMed] [Google Scholar]
McColl 2003b {published data only}
- McColl E, Eccles MP, Rousseau NS, Steen IN, Parkin DW, Grimshaw JM. From the generic to the condition-specific? Instrument order effects in quality of life assessment. Medical Care 2003b;7:777–90. [DOI] [PubMed] [Google Scholar]
McConochie 1985 {published data only}
- McConochie RM, Rankin CA. Effects of monetary premium variations on response/non response bias: representation of black and non black respondents in surveys of radio listening. Proceeding of the Section on Survey, American Statistical Association 1985;2:42-5. [Google Scholar]
McCormack 2013 {published data only}
- McCormack LA. Effect of Small Monetary Incentive and Demographic Characteristics on Response Rate of Self-Administered Questionnaire Mailed to Rural Women. Online J Rural Res Policy 2013;8(1):1. [DOI] [PMC free article] [PubMed] [Google Scholar]
McCoy 2007 {published data only}
- McCoy M, Hargie O. Effects of personalization and envelope color on response rate, speed and quality among a business population. Industrial Marketing Management 2007;36:799–809. [Google Scholar]
McDaniel 1980 {published data only}
- McDaniel SW. The effect of monetary inducement on mailed questionnaire response quality. Journal of Marketing Research 1980;17:265-8. [Google Scholar]
McDaniel 1981 {published data only}
- McDaniel SW. An investigation of respondent anonymity’s effect on mailed questionnaire response rate and quality. Journal of the Market Research Society 1981;23(3):150-60. [Google Scholar]
McGonagle 2017 {published data only}
- McGonagle K A, Freedman V A. The Effects of a Delayed Incentive on Response Rates, Response Mode, Data Quality, and Sample Bias in a Nationally Representative Mixed Mode Study. FIELD METHODS 2017;29(3):221-37. [DOI] [PMC free article] [PubMed] [Google Scholar]
McKee 1992 {published data only}
- McKee D. The effect of using a questionnaire identification code and message about non-response follow-up plans on mail survey response characteristics. Journal of the Market Research Society 1992;34(2):179-91. [Google Scholar]
McKenzie‐McHarg 2005 {published data only}
- McKenzie-McHarg K, Tully L, Gates S, Ayers S, Brocklehurst P. Effect on survey response rate of hand written versus printed signature on a covering letter: randomised controlled trial. BMC Health Services Research 2005;5(52):1-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
McKillip 1984 {published data only}
- McKillip J, Lockhart DC. The effectiveness of cover-letter appeals. Journal of Social Psychology 1984;122:85-91. [Google Scholar]
McLaren 2000a {published data only}
- McLaren B, Shelley J. Response rates of Victorian general practitioners to a mailed survey on miscarriage: randomised trial of a prize and two forms of introduction to the research. Australian and New Zealand Journal of Public Health 2000;24(4):360-4. [DOI] [PubMed] [Google Scholar]
McLaren 2000b {published data only}
- McLaren B, Shelley J. Response rates of Victorian general practitioners to a mailed survey on miscarriage: randomised trial of a prize and two forms of introduction to the research. Australian and New Zealand Journal of Public Health 2000;24(4):360-4. [DOI] [PubMed] [Google Scholar]
McLean 2014 {published data only}
- McLean S A, Paxton S J, Massey R, Mond J M, Rodgers B, Hay P J. Prenotification but not envelope teaser increased response rates in a bulimia nervosa mental health literacy survey: A randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2014;67(8):870-6. [DOI] [PubMed] [Google Scholar]
Meadows 2000 {published data only}
- Meadows KA, Greene T, Foster L, Beer S. The impact of different response alternatives on responders' reporting of health-related behaviour in a postal survey. Quality of Life Research 2000;9:385-91. [DOI] [PubMed] [Google Scholar]
Meuleman 2017 {published data only}
- Meuleman Bart, Langer Arnim, Blom Annelies G. Can Incentive Effects in Web Surveys Be Generalized to Non-Western Countries? Conditional and Unconditional Cash Incentives in a Web Survey of Ghanaian University Students. SOCIAL SCIENCE COMPUTER REVIEW 2017;36(2):231-50. [Google Scholar]
Millar 2011a {published data only}
- Millar Morgan M, Dillman Don A. IMPROVING RESPONSE TO WEB AND MIXED-MODE SURVEYS. The Public Opinion Quarterly 2011;75(2):249-69. [Google Scholar]
Millar 2011b {published data only}
- Millar Morgan M, Dillman Don A. IMPROVING RESPONSE TO WEB AND MIXED-MODE SURVEYS. The Public Opinion Quarterly 2011;75(2):249-69. [Google Scholar]
Millar 2019 {published data only}
- Millar Morgan M, Elena Joanne W, Gallicchio Lisa, Edwards Sandra L, Carter Marjorie E, Herget Kimberly A, et al. The feasibility of web surveys for obtaining patient-reported outcomes from cancer survivors: a randomized experiment comparing survey modes and brochure enclosures. BMC medical research methodology 2019;19(1):208. [DOI] [PMC free article] [PubMed] [Google Scholar]
Miller 1994 {published data only}
- Miller MM. The effects of cover letter appeal and non monetary incentives on university professors' response to a mail survey. Paper presented at the annual meeting of the American Educational Research Association 1994.
Mills 2019 {published data only}
- Mills S. A $2 Bill or Two $1 Bills: An Experiment that Challenges Standard Protocol. FIELD METHODS 2019;31(3):230-40. [Google Scholar]
Mitchell 2011 {published data only}
- Mitchell N, Hewitt C E, Torgerson D J, Grp Scoop Trial. A controlled trial of envelope colour for increasing response rates in older women. AGING CLINICAL AND EXPERIMENTAL RESEARCH 2011;23(3):236-40. [DOI] [PubMed] [Google Scholar]
Mitchell 2012 {published data only}
- Mitchell N, Hewitt C E, Lenaghan E, Platt E, Shepstone L, Torgerson D J, et al. Prior notification of trial participants by newsletter increased response rates: a randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2012;65(12):1348-52. [DOI] [PubMed] [Google Scholar]
Mitchell 2021a {published data only}
- Mitchell Alex S, Cook Liz, Dean Alexandra, Fairhurst Caroline, Torgerson David J, Northgraves Matthew, et al. An embedded randomised controlled retention trial ofpersonalised text messages compared to non-personalised text messages in an orthopaedic setting [version 1; peer review: 1 approved]. F1000Research 2021;9((Mitchell, Cook, Dean, Fairhurst, Torgerson, Reed) Department of Health Sciences, University of York, York Y010 5DD, United Kingdom(Northgraves) Hull Health Trials Unit, University of Hull, Hull HU6 7RU, United Kingdom(Reed) North Tyneside General Hospita):1-8. [Google Scholar]
Mitchell 2021b {published data only}
- Mitchell A S, Cook L, Dean A, Fairhurst C, Northgraves M, Torgerson D J, et al. Using pens as an incentive for questionnaire return in an orthopaedic trial: an embedded randomised controlled retention trial. F1000Research 2021;9:321. [DOI] [PMC free article] [PubMed] [Google Scholar]
Mizes 1984 {published data only}
- Mizes JS, Fleece EL, Roos C. Incentives for increasing return rates: magnitude levels, response bias, and format. Public Opinion Quarterly 1984;48(4):794-800. [Google Scholar]
Mockovak 2012 {published data only}
- Mockovak W. The Impact of Visual Design in Survey Cover Letters on Response and Web Take‐Up Rates. U S Bureau of Labor Statistics 2012;https://www.bls.gov/osmr/research-papers/2011/pdf/st110040.pdf.
Mond 2004 {published data only}
- Mond JM, Rodgers B, Hay PJ, Owen C, Beumont PJV. Mode of delivery, but not questionnaire length, affected response in an epidemiological study of eating-disordered behavior. Journal of Clinical Epidemiology 2004;57:1167–71. [DOI] [PubMed] [Google Scholar]
Morgan 2017 {published data only}
- Morgan A J, Rapee R M, Bayer J K. Increasing response rates to follow-up questionnaires in health intervention research: Randomized controlled trial of a gift card prize incentive. CLINICAL TRIALS 2017;14(4):381-6. [DOI] [PubMed] [Google Scholar]
Morris 2013 {published data only}
- Morris M, Edwards P, Doyle P, Maconochie N. Women in an infertility survey responded more by mail but preferred a choice: randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2013;66(2):226-35. [DOI] [PubMed] [Google Scholar]
Morrison 2003 {published data only}
- Morrison DS, Thomson H, Petticrew M. Effects of disseminating research findings on response rates in a community survey: a randomised controlled trial. Journal of Epidemiology and Community Health 2003;57:536-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
Mortagy 1985 {published data only}
- Mortagy AK, Howell JB, Waters WE. A useless raffle. Journal of Epidemiology and Community Health 1985;39:183-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Moses 2004 {published data only}
- Moses SH, Clark TJ. Effect of prize draw incentive on the response rate to a postal survey of obstetricians and gynaecologists: a randomised controlled trial. BMC Health Services Research 2004;4(14):1-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
Moss 1991 {published data only}
- Moss VD, Worthen BR. Do personalization and postage make a difference on response rates to surveys of professional populations. Psychological Reports 1991;68:692-4. [Google Scholar]
Mullen 1987 {published data only}
- Mullen P, Easling I, Nixon SA, Koester DR, Biddle AK. The cost-effectiveness of randomised incentive and follow-up contacts in a national mail survey of family physicians. Evaluation & the Health Professions 1987;10(2):232-45. [Google Scholar]
Mullner 1982 {published data only}
- Mullner RM, Levy PS, Byre CS, Matthews D. Effects of characteristics of the survey instrument on response rates to a mail survey of community hospitals. Public Health Reports 1982;97(5):465-9. [PMC free article] [PubMed] [Google Scholar]
Munoz 2017 {published data only}
- Munoz R F, Leykin Y, Barrera A Z, Brown C H, Bunge E L. The impact of phone calls on follow-up rates in an online depression prevention study. Internet interventions 2017;8(101631612):10-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Murawski 1996 {published data only}
- Murawski MM, Carroll NV. Direct mail performance of selected health related quality of life scales. Journal of Pharmacoepidemiology 1996;5(1):17-38. [Google Scholar]
Murdoch 2014 {published data only}
- Murdoch M, Simon A B, Polusny M A, Bangerter A K, Grill J P, Noorbaloochi S, et al. Impact of different privacy conditions and incentives on survey response rate, participant representativeness, and disclosure of sensitive information: a randomized controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2014;14:90. [DOI] [PMC free article] [PubMed] [Google Scholar]
Murphy 1991 {published data only}
- Murphy PM, Daley JM. Exploring the effects of postcard prenotification on industiral firms' response to mail surveys. Journal of the Market Research Society 1991;33(4):335-41. [Google Scholar]
Murphy 2020 {published data only}
- Murphy Caitlin C, Craddock Lee Simon J, Geiger Ann M, Cox John V, Ahn Chul, Nair Rasmi, et al. A randomized trial of mail and email recruitment strategies for a physician survey on clinical trial accrual. BMC medical research methodology 2020;20(1):123. [DOI] [PMC free article] [PubMed] [Google Scholar]
Myers 1969 {published data only}
- Myers JH, Haug AF. How a preliminary letter affects mail survey returns and costs. Journal of Advertising Research 1969;9(3):37-9. [Google Scholar]
Myhre 2019a {published data only}
- Myhre J B, Andersen L F, Holvik K, Astrup H, Kristiansen A L. Means of increasing response rates in a Norwegian dietary survey among infants - results from a pseudo-randomized pilot study. BMC MEDICAL RESEARCH METHODOLOGY 2019;19:144. [DOI] [PMC free article] [PubMed] [Google Scholar]
Myhre 2019b {published data only}
- Myhre J B, Andersen L F, Holvik K, Astrup H, Kristiansen A L. Means of increasing response rates in a Norwegian dietary survey among infants - results from a pseudo-randomized pilot study. BMC MEDICAL RESEARCH METHODOLOGY 2019;19:144. [DOI] [PMC free article] [PubMed] [Google Scholar]
Nagata 1995 {published data only}
- Nagata C, Hara S, Shimizu H. Factors affecting response to mail questionnaire: research topics, questionnaire length, and non-response bias. Journal of Epidemiology 1995;5(5):81-5. [Google Scholar]
Nakai 1997 {published data only}
- Nakai S, Hashimoto S, Murakami Y, Hayashi M, Manabe K, Noda H. Response rates and non-response bias in a health-related mailed survey. Nippon-Koshu-Eisei-Zasshi 1997;44(3):184-91. [PubMed] [Google Scholar]
Nakash 2007 {published data only}
- Nakash Rachel Anne. A study of response and non-response to postal questionnaire follow-up in clinical trials. Thesis (Ph.D.) - University of Warwick, 2007. 2007:1.
Nakazawa 2020 {published data only}
- Nakazawa Y, Takeuchi E, Miyashita M, Sato K, Ogawa A, Kinoshita H, Kizawa Y, Morita T, Kato M. A Population-based Mortality Follow-Back Survey Evaluating Good Death for Cancer and Non-cancer Patients: A Randomized Feasibility Study. Journal of pain and symptom management 2020;61(1):42-53. [DOI] [PubMed] [Google Scholar]
Napoles‐Springer 2004 {published data only}
- Napoles-Springer AM, Fongwa MN, Stewart AL, Gildengorin G, Perez-Stable EJ. The effectiveness of an advance notice letter on the recruitment of African Americans and Whites for a mailed patient satisfaction survey. Journal of Aging & Health 2004;16(5 Suppl):124S-36S. [DOI] [PubMed] [Google Scholar]
Nathenson 2019 {published data only}
- Nathenson R A, Supovitz J. Variation in Motivational Appeals to Survey Completion: Lessons from a Randomized Experiment with Teachers. JOURNAL OF RESEARCH ON EDUCATIONAL EFFECTIVENESS 2019;12(2):307-31. [Google Scholar]
Nederhof 1982 {published data only}
- Nederhof AJ. Effects of preliminary contacts on volunteering in mail surveys. Perceptual and Motor Skills 1982;54:1333-4. [Google Scholar]
Nederhof 1983a {published data only}
- Nederhof AJ. Effects of repetition and consistency of personalization treatments on response rate in mail surveys. Social Science Research 1983a;12:1-9. [Google Scholar]
Nederhof 1983b {published data only}
- Nedefhof AJ. Effects of repetition and consistency of personalization treatments on response rate in mail surveys. Social Science Research 1983b;12:1-9. [Google Scholar]
Nederhof 1988 {published data only}
- Nedefhof AJ. Effects of a final telephone reminder and questionnaire cover design in mail surveys. Social Science Research 1988;17:353-61. [Google Scholar]
Neider 1981a {published data only}
- Neider L, Sugrue P. Personalization as a response inducement technique in mail surveys. American Institute of Decision Sciences 1981;13:238-9. [Google Scholar]
Neider 1981b {published data only}
- Neider L, Sugrue P. Personalization as a response inducement technique in mail surveys. American Institute of Decision Sciences 1981;13:238-9. [Google Scholar]
Nesrallah 2014 {published data only}
- Nesrallah Gihad, Barnieh Lianne, Manns Braden, Clase Catherine, Mendelssohn David, Guyatt Gordon. A charitable donation incentive did not increase physician survey response rates in a randomized trial. Journal of clinical epidemiology 2014;67(4):482-3. [DOI] [PubMed] [Google Scholar]
Nevin 1975a {published data only}
- Nevin JR, Ford NM. Effects of a deadline and veiled threat on mail survey responses. Journal of Applied Psychology 1975;61(1):116-8. [Google Scholar]
Nevin 1975b {published data only}
- Nevin JR, Ford NM. Effects of a deadline and veiled threat on mail survey responses. Journal of Applied Psychology 1975;61(1):116-8. [Google Scholar]
Newby 2003 {published data only}
- Newby R, Watson J, Woodliff D. SME survey methodology: response rates, data quality, and cost effectiveness. Entrepreneurship Theory and Practice 2003;28(2):163-72. [Google Scholar]
Newland 1977 {published data only}
- Newland CA, Waters WE, Standford AP, Batchelor BG. A study of mail survey method. International Journal of Epidemiology 1977;6(1):65-7. [DOI] [PubMed] [Google Scholar]
Nichols 1966 {published data only}
- Nichols RC, Meyer MA. Timing postcard follow-ups in mail questionnaire surveys. Public Opinion Quarterly 1966;30:3006-7. [Google Scholar]
Nichols 1988 {published data only}
- Nichols S, Waters WE, Woolaway M, Hamilton-Smith MB. Evaluation of the effectiveness of a nutritional health education leaflet in changing public knowledge and attitudes about eating and health. Journal of Human Nutrition and Dietetics 1988;1:233-8. [Google Scholar]
Nicolaas 2015 {published data only}
- Nicolaas G, Smith P, Pickering K, Branson C. Increasing response rates in postal surveys while controlling costs: an experimental investigation. Social Research Practice 2015;1:3-16. [Google Scholar]
Noel 2018 {published data only}
- Noel HarmoniJoie, Huang Alison R. The Effect of Varying Incentive Amounts on Physician Survey Response. EVALUATION & THE HEALTH PROFESSIONS 2018;42(1):71-81. [DOI] [PubMed] [Google Scholar]
O'Connor 2011 {published data only}
- O'Connor M. The challenge of recruiting control groups. An experiment of different recruitment models in the control group of a clinical psychological postal survey. QUALITY & QUANTITY 2011;45(4):743-50. [Google Scholar]
Ogborne 1986 {published data only}
- Ogbourne AC, Rush B, Fondacaro R. Dealing with nonrespondents in a mail survey of professionals. Evaluation & the Health Professions 1986;9(1):121-8. [Google Scholar]
Olivarius 1995 {published data only}
- Olivarius N de F, Andreasen AH. Day-of-the-week effect on doctors' response to a postal questionnaire. Scandinavian Journal of Primary Health Care 1995;13:65-7. [DOI] [PubMed] [Google Scholar]
Olsen 2012 {published data only}
- Olsen Frank, Abelsen Birgit, Olsen Jan Abel. Improving response rate and quality of survey data with a scratch lottery ticket incentive. BMC Medical Research Methodology 2012;12(1):52. [DOI] [PMC free article] [PubMed] [Google Scholar]
Osborne 1996 {published data only}
- Osborne MO, Ward J, Boyle C. Effectiveness of telephone prompts when surveying general practitioners: a randomised trial. Australian Family Physician 1996;25(1):S41-3. [PubMed] [Google Scholar]
Pace 2020 {published data only}
- Pace Lydia E, Lee Yeonsoo S, Tung Nadine, Hamilton Jada G, Gabriel Camila, Raja Sahitya C, et al. Comparison of up-front cash cards and checks as incentives for participation in a clinician survey: a study within a trial. BMC medical research methodology 2020;20(1):210. [DOI] [PMC free article] [PubMed] [Google Scholar]
Paolillo 1984 {published data only}
- Paolillo JG, Lorenzi P. Monetary incentives and mail questionnaire response rates. Journal of Advertising 1984;131:46-8. [Google Scholar]
Parasuraman 1981 {published data only}
- Parasuraman A. Impact of cover letter detail on response patterns in a mail survey. American Institute of Decision Science 1981;13th Meeting:289-91. [Google Scholar]
Parker 2019 {published data only}
- A Parker, S Brealey, A Keding, L Kottam, A Mitchell, M Northgraves, PP Sarathy, C Welch, A Rangan. Timing of text message reminders to increase trial participant response to postal questionnaires: An embedded randomized trial. Trials 2019;20(Supplement 1):579. [Google Scholar]
Parkes 2000a {published data only}
- Parkes R, Kreiger N, James B, Johnson KC. Effects on subject response of information brochures and small cash incentives in a mail-based case-control study. Annals of Epidemiology 2000;10:117-24. [DOI] [PubMed] [Google Scholar]
Parkes 2000b {published data only}
- Parkes R, Kreiger N, James B, Johnson KC. Effects on subject response of information brochures and small cash incentives in a mail-based case-control study. Annals of Epidemiology 2000;10:117-24. [DOI] [PubMed] [Google Scholar]
Parsons 1972a {published data only}
- Parsons RJ, Medford TS. The effect of advance notice in mail surveys of homogeneous groups. Public Opinion Quarterly 1972;36:258-9. [Google Scholar]
Parsons 1972b {published data only}
- Parsons RJ, Medford TS. The effect of advance notice in mail surveys of homogenous groups. Public Opinion Quarterly 1972;36:258-9. [Google Scholar]
Patrick 2013 {published data only}
- Patrick Megan E, Singer Eleanor, Boyd Carol J, Cranford James A, McCabe Sean Esteban. Incentives for college student participation in web-based substance use surveys. Addictive behaviors 2013;38(3):1710-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
Patrick 2018 {published data only}
- Patrick Megan E, Couper Mick P, Laetz Virginia B, Schulenberg John E, O'Malley Patrick M, Johnston Lloyd D, et al. A Sequential Mixed-Mode Experiment in the U.S. National Monitoring the Future Study. Journal of survey statistics and methodology 2018;6(1):72-97. [DOI] [PMC free article] [PubMed] [Google Scholar]
Paul 2005 {published data only}
- Paul CL, Walsh RA, Tzelepis F. A monetary incentive increases postal survey response rates for pharmacists. Journal of Epidemiology and Community Health 2005;59:1099-101. [DOI] [PMC free article] [PubMed] [Google Scholar]
Pearson 2003 {published data only}
- Pearson J, Levine RA. Salutations and Response Rates to Online Surveys. Association for Survey Computing, Fourth International Conference on the Impact of Technology on the Survey Process 2003;1:1-9. [Google Scholar]
Peck 1981 {published data only}
- Peck JK, Dresch SP. Financial incentives, survey response, and sample representativeness: does money matter? Review of Public Data Use 1981;9:245-66. [Google Scholar]
Pedersen 2016 {published data only}
- Pedersen M J, Nielsen C V. Improving Survey Response Rates in Online Panels: Effects of Low-Cost Incentives and Cost-Free Text Appeal Interventions. SOCIAL SCIENCE COMPUTER REVIEW 2016;34(2):229-43. [Google Scholar]
Pedrana 2008 {published data only}
- Pedrana A, Hellard M, Giles M. Registered post achieved a higher response rate than normal mail - A randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2008;61(9):896-9. [DOI] [PubMed] [Google Scholar]
Pejtersen 2020 {published data only}
- Pejtersen JH. The effect of monetary incentive on survey response for vulnerable children and youths: A randomized controlled trial. PLOS ONE 2020;15(5):e0233025. [DOI] [PMC free article] [PubMed] [Google Scholar]
Perneger 1993 {published data only}
- Perneger TV, Etter J-F, Rougemont A. Randomized trial of use of a monetary incentive and a reminder card to increase the response rate to a mailed questionnaire. American Journal of Epidemiology 1993;138(9):714-22. [DOI] [PubMed] [Google Scholar]
Perry 1974 {published data only}
- Perry N. Postage combinations in postal questionnaire surveys - another view. Journal of the Market Research Society 1974;16(3):245-6. [Google Scholar]
Peters 1998 {published data only}
- Peters TJ, Harvey IM, Bachmann MO, Eachus JI. Does requesting sensitive information on postal questionnaires have an impact on response rates? A randomised controlled trial in the south west of England. Journal of Epidemiology and Community Health 1998;52:130. [DOI] [PMC free article] [PubMed] [Google Scholar]
Peterson 1975 {published data only}
- Peterson RA. An experimental investigation of mail survey responses. Journal of Business Research 1975;3(3):199-210. [Google Scholar]
Petrovčič 2016 {published data only}
- Petrovčič Andraž, Petrič Gregor, Lozar Manfreda Katja. The effect of email invitation elements on response rate in a web survey within an online community. Computers in Human Behavior 2016;56:320-9. [Google Scholar]
Phillips 1951 {published data only}
- Phillips WM. Weaknesses of the mail questionnaire: a methodological study. Sociology & Social Research 1951;35:260-7. [Google Scholar]
Pirotta 1999 {published data only}
- Pirotta M, Gunn J, Farish S, Karabatsos G. Primer postcard improves postal survey response rates. Australian and New Zealand Journal of Public Health 1999;23(2):196-7. [DOI] [PubMed] [Google Scholar]
Pit 2013 {published data only}
- Pit S W, Hansen V, Ewald D. A small unconditional non-financial incentive suggests an increase in survey response rates amongst older general practitioners (GPs): a randomised controlled trial study. BMC FAMILY PRACTICE 2013;14:108. [DOI] [PMC free article] [PubMed] [Google Scholar]
Poe 1988 {published data only}
- Poe GS, Seeman I, McLaughlin J, Mehl E, Dietz M. 'Don't know' boxes in factual questions in a mail questionnaire. Public Opinion Quarterly 1988;52:212-22. [Google Scholar]
Porter 2003a {published data only}
- Porter SR, Whitcomb ME. The impact of lottery incentives on student survey response rates. Research in Higher Education 2003;44(4):389-407. [Google Scholar]
Porter 2003b {published data only}
- Porter SR, Whitcomb ME. The impact of contact type on web survey response rates. Public Opinion Quarterly 2003b;67:579–88. [Google Scholar]
Porter 2005a {published data only}
- Porter SR, Whitcomb ME. E-mail subject lines and their effect on web survey viewing and response. Social Science Computer Review 2005;23:280-7. [Google Scholar]
Porter 2005b {published data only}
- Porter SR, Whitcomb ME. E-mail subject lines and their effect on web survey viewing and response. Social Science Computer Review 2005;23:280-7. [Google Scholar]
Porter S 2003b {published data only}
- Porter SR, Whitcomb ME. The impact of contact type on web survey response rates. Public Opinion Quarterly 2003b;67:579–88. [Google Scholar]
Pourjalali 1994 {published data only}
- Pourjalali H, Kimbrell J. Effects of four instrumental variables on survey response. Psychological Reports 1994;75:895-8. [Google Scholar]
Powers 1982 {published data only}
- Powers DE, Alderman DL. Feedback as an incentive for responding to a mail questionnaire. Research in Higher Education 1982;17(3):207-11. [Google Scholar]
Pressley 1977 {published data only}
- Pressley MM, Tullar WL. A factor interactive investigation of mail survey response rates from a commercial population. Journal of Marketing Research 1977;14:108-11. [Google Scholar]
Pressley 1978 {published data only}
- Pressley MM. Care needed when selecting response inducements in mail surveys of commercial populations. Journal of the Academy of Marketing Science 1978;6(4):336-43. [Google Scholar]
Pressley 1985 {published data only}
- Pressley MM, Dunn MG. A factor-interactive experimental investigation of inducing response to questionnaires mailed to commercial populations. AMA Educators Conference Proceedings 1985;14(1):356-61. [Google Scholar]
Price 1996 {published data only}
- Price JH, Easton A, Kandakai T, Oden L. Race-specific versus general stamps on African-American women's survey return rates. Perceptual and Motor Skills 1996;82:928-30. [DOI] [PubMed] [Google Scholar]
Price 2003 {published data only}
- Price JH, Dake JA, Akpanudo S, Kleinfelder J. The effect of survey return rates of having a signed or unsigned postcard as the third wave mailing. Psychological Reports 2003;92(2):1099-102. [DOI] [PubMed] [Google Scholar]
Price 2010 {published data only}
- Price James H, Khubchandani Jagdish, Bryant Michele, Rickard Megan, Hendershot Candace, Thompson Amy. Survey return rates for multiple-authored versus single-authored covering letters. Psychological reports 2010;107(1):209-12. [DOI] [PubMed] [Google Scholar]
Price 2014 {published data only}
- Price A M H, Coates C, Symeonides C, Hiscock H, Smith L, York E, et al. Chocolate frogs do not increase completion of parent survey: Randomised study. JOURNAL OF PAEDIATRICS AND CHILD HEALTH 2014;50(11):866-8. [DOI] [PubMed] [Google Scholar]
Pucel 1971 {published data only}
- Pucel DJ, Nelson HF, Wheeler DN. Questionnaire follow-up returns as a function of incentives and responder characteristics. Vocational Guidance Quarterly 1971;March:188-93. [Google Scholar]
Puffer 2004 {published data only}
- Puffer S, Porthouse J, Birks Y, Morton V, Torgerson D. Increasing response rates to postal questionnaires: a randomised trial of variations in design. Journal of Health Services Research & Policy 2004;9(4):213–7. [DOI] [PubMed] [Google Scholar]
Rach 2020 {published data only}
- Rach S, Gunther K, Hadeler B. Participants who were difficult to recruit at baseline are less likely to complete a follow-up questionnaire - results from the German National Cohort. BMC MEDICAL RESEARCH METHODOLOGY 2020;20(1):187. [DOI] [PMC free article] [PubMed] [Google Scholar]
Rath 2017 {published data only}
- Rath J M, Williams V F, Villanti A C, Green M P, Mowery P D, Vallone D M. Boosting Online Response Rates Among Nonresponders: A Dose of Funny. SOCIAL SCIENCE COMPUTER REVIEW 2017;35(5):619-32. [Google Scholar]
Recklitis 2009 {published data only}
- Recklitis C J, Campbell E G, Kutner J S, Bober S L. Money talks: non-monetary incentive and Internet administration fail to increase response rates to a physician survey. JOURNAL OF CLINICAL EPIDEMIOLOGY 2009;62(2):224-6. [DOI] [PubMed] [Google Scholar]
Rego 2020 {published data only}
- Rego Ryan, Watson Samuel, Ishengoma Philbert, Langat Philemon, Otieno Hezekiah Pireh, Lilford Richard. Effectiveness of SMS messaging for diarrhoea measurement: a factorial cross-over randomised controlled trial. BMC medical research methodology 2020;20(1):174. [DOI] [PMC free article] [PubMed] [Google Scholar]
Reinisch 2016 {published data only}
- Reinisch John F, Yu Daniel C, Li Wai-Yee. Getting a Valid Survey Response From 662 Plastic Surgeons in the 21st Century. Annals of plastic surgery 2016;76(1):3-5. [DOI] [PubMed] [Google Scholar]
Renfroe 2002 {published data only}
- Renfroe EG, Heywood G, Foreman L, Schron E, Powell J, Baessler C, et al, for the AVID Coordinators and Investigators. The end-of-study patient survey: methods influencing response rate in the AVID Trial. Controlled Clinical Trials 2002;23:521-33. [DOI] [PubMed] [Google Scholar]
Riesenberg 2006 {published data only}
- Riesenberg LA, Rosebaum P, Stick SL. Unexpected mailed survey response rates. Family Medicine 2006;38(2):83. [PubMed] [Google Scholar]
Rikard‐Bell 2000 {published data only}
- Rikard-Bell G, Ward J. Maximizing response rates to a survey of dentists: a randomized trial. Australian Dental Journal 2000;45(1):46-8. [DOI] [PubMed] [Google Scholar]
Rimm 1990 {published data only}
- Rimm EB, Stampfer MJ, Colditz GA, Giovannuci E, Willet WC. Effectiveness of various mailing strategies among nonrespondents in a prospective cohort study. American Journal of Epidemiology 1990;131(6):1068-71. [DOI] [PubMed] [Google Scholar]
Robb 2017 {published data only}
- Robb K A, Gatting L, Wardle J. What impact do questionnaire length and monetary incentives have on mailed health psychology survey response? BRITISH JOURNAL OF HEALTH PSYCHOLOGY 2017;22(4):671-85. [DOI] [PMC free article] [PubMed] [Google Scholar]
Roberts 1978 {published data only}
- Roberts RE, McCrory OF, Forthofer RN. Further evidence on using a deadline to stimulate responses to a mail survey. Public Opinion Quarterly 1978;42:407-10. [Google Scholar]
Roberts 1993 {published data only}
- Roberts H, Pearson JC, Dengler R. Impact of a postcard versus a questionnaire as a first reminder in a postal lifestyle survey. Journal of Epidemiology and Community Health 1993;47:334-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Roberts 1994 {published data only}
- Roberts I, Coggan C, Fanslow J. Epidemiological methods: the effect of envelope type on response rates in an epidemiological study of back pain. Aust NZ Journal of Occupational Health and Safety 1994;10(1):55-7. [Google Scholar]
Roberts 2000 {published data only}
- Roberts P-J, Roberts C, Sibbald B, Torgerson DJ. The effect of a direct payment or a lottery on questionnaire response rates: a randomised controlled trial. Journal of Epidemiology and Community Health 2000;54:71-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
Roberts 2004 {published data only}
- Roberts LM, Wilson S, Roalfe A, Bridge P. A randomised controlled trial to determine the effect on response of including a lottery incentive in health surveys. BMC Health Services Research 2004;4(30):1-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
Robertson 1978 {published data only}
- Robertson DH, Bellenger DN. A new method of increasing mail survey responses: Contributions to charity. Journal of Marketing Research 1978;15:632-3. [Google Scholar]
Robertson 2005 {published data only}
- Robertson J, Walkom EJ, McGettigan P. Response rates and representativeness: a lottery incentive improves physician survey response rates. Pharmacoepidemiology and Drug Safety 2005;14:571-7. [DOI] [PubMed] [Google Scholar]
Rodgers 2018 {published data only}
- Rodgers S, Sbizzera I, Cockayne S, Fairhurst C, Lamb S E, Vernon W, et al. A study update newsletter or Post-it® note did not increase postal questionnaire response rates in a falls prevention trial: an embedded randomised factorial trial. f1000research 2018;16(7):1083. [DOI] [PMC free article] [PubMed] [Google Scholar]
Rolnick 1989 {published data only}
- Rolnick SJ, Gross CR, Garrard J, Gibson RW. A comparison of response rate, data quality, and cost in the collection of data on sexual history and personal behaviours. American Journal of Epidemiology 1989;129(5):1052-61. [DOI] [PubMed] [Google Scholar]
Romney 1993 {unpublished data only}
- Romney VA. A comparison of responses to open-ended and closed ended items on a state-level community education needs assessment instrument. Doctoral Dissertation 1993.
Ronckers 2004 {published data only}
- Ronckers C, Land C, Hayes R, Verdunijn P, Van LeeUwen F. Factors impacting questionnaire response in a Dutch retrospective cohort study. Annals of Epidemiology 2004;14(1):66–72. [DOI] [PubMed] [Google Scholar]
Roscoe 1975 {published data only}
- Roscoe AM, Lang D, Sheth JN. Follow-up methods, questionnaire length, and market differences in mail surveys. Journal of Marketing 1975;39:20-7. [Google Scholar]
Rose 2007a {published data only}
- Rose DS, Sidle SD, Griffith KH. A penny for your thoughts. Monetary incentives improve response rates for company-sponsored employee surveys. Organizational Research Methods 2007a;10(2):225-40. [Google Scholar]
Rose 2007b {published data only}
- Rose DS, Sidle SD, Griffith KH. A penny for your thoughts. Monetary incentives improve response rates for company-sponsored employee surveys. Organizational Research Methods 2007;10(2):225-40. [Google Scholar]
Rosoff 2005a {published data only}
- Rosoff PM, Werner C, Clipp EC, Guill AB, Bonner M, Demark-Wahnefried W. Response rates to a mailed survey targeting childhood cancer survivors: A comparison of conditional versus unconditional incentives. Cancer Epidemiology, Biomarkers & Prevention 2005a;14(5):1330-2. [DOI] [PubMed] [Google Scholar]
Rosoff 2005b {published data only}
- Rosoff PM, Werner C, Clipp EC, Guill AB, Bonner M, Demark-Wahnefried W. Response rates to a mailed survey targeting childhood cancer survivors: A comparison of conditional versus unconditional incentives. Cancer Epidemiology, Biomarkers & Prevention 2005b;14(5):1330-2. [DOI] [PubMed] [Google Scholar]
Rosoff 2005c {published data only}
- Rosoff PM, Werner C, Clipp EC, Guill AB, Bonner M, Demark-Wahnefried W. Response rates to a mailed survey targeting childhood cancer survivors: A comparison of conditional versus unconditional incentives. Cancer Epidemiology, Biomarkers & Prevention 2005c;14(5):1330-2. [DOI] [PubMed] [Google Scholar]
Roszkowski 1990a {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990b {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990c {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990d {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990e {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990f {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990g {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990h {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990i {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990j {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990k {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990l {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990m {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Roszkowski 1990n {published data only}
- Roszkowski MJ, Bean AG. Believe it or not! Longer questionnaires have lower response rates. Journal of Business and Psychology 1990;4(4):495-509. [Google Scholar]
Rucker 1979a {published data only}
- Rucker MH, Arbaugh JE. A comparison of matrix questionnaires with standard questionnaires. Educational and Psychological Measurement 1979;39:637-43. [Google Scholar]
Rucker 1979b {published data only}
- Rucker MH, Arbaugh JE. A comparison of matrix questionnaires with standard questionnaires. Educational and Psychological Measurement 1979;39:637-43. [Google Scholar]
Rucker 1984 {published data only}
- Rucker M et al. Personalization of mail surveys: too much of a good thing? Educational and Psychological Measurement 1984;44(4):893-905. [Google Scholar]
Russell 2003 {published data only}
- Russell ML, Mutasingwa DR, Verhoef MJ, Injeyan HS. Effect of a monetary incentive on chiropractors’ response rate and time to respond to a mail survey. Journal of Clinical Epidemiology 2003;56:1027–8. [DOI] [PubMed] [Google Scholar]
Ryu 2006 {published data only}
- Ryu E, Couper MP, Marans RW. Survey incentives: cash vs. in-kind; face-to-face vs. mail; response rate vs. nonresponse error. International Journal of Public Opinion Research 2006;18(1):89-106. [Google Scholar]
Saal 2005 {published data only}
- Saal D, Nuebling M, Husemann Y, Heidegger T. Effect of timing on the response to postal questionnaires concerning satisfaction with anaesthesia care. British Journal of Anaesthesia 2005;94(2):206–10. [DOI] [PubMed] [Google Scholar]
Sahlqvist 2011 {published data only}
- Sahlqvist Shannon, Song Yena, Bull Fiona, Adams Emma, Preston John, Ogilvie David, et al. Effect of questionnaire length, personalisation and reminder type on response rate to a complex postal survey: randomised controlled trial. BMC medical research methodology 2011;11(100968545):62. [DOI] [PMC free article] [PubMed] [Google Scholar]
Sakshaug 2019 {published data only}
- Sakshaug Joseph W, Vicari Basha, Couper Mick P. Paper, e-mail, or both? Effects of contact mode on participation in a web survey of establishments. Social Science Computer Review 2019;37(6):750-65. [Google Scholar]
Salim Silva 2002 {published data only}
- Salim Silva M, Smith WT, Bammer G. Telephone reminders are a cost effective way to improve responses in postal health surveys. Journal of Epidemiology and Community Health 2002;56:115-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
Sallis 1984 {published data only}
- Sallis JF, Fortmann SP, Solomon DS, Farquhar JW. Increasing returns of physician surveys. American Journal of Public Health 1984;74(9):1043. [DOI] [PMC free article] [PubMed] [Google Scholar]
Salvesen 1992 {published data only}
- Salvesen K, Vatten L. Effect of a newspaper article on the response to a postal questionnaire. Journal of Epidemiology and Community Health 1992;46:86. [DOI] [PMC free article] [PubMed] [Google Scholar]
Sang‐Wook 2005 {published data only}
- Sang-Wook Y, Hong JS, Ohr H, Yi JJ. A comparison of response rate and time according to the survey methods used: a randomized controlled trial. European Journal of Epidemiology 2005;20:131–5. [DOI] [PubMed] [Google Scholar]
Satia 2005 {published data only}
- Satia J A, Galanko J A, Rimer B K. Methods and strategies to recruit African Americans into cancer prevention surveillance studies. CANCER EPIDEMIOLOGY BIOMARKERS & PREVENTION 2005;14(3):718-21. [DOI] [PubMed] [Google Scholar]
Sauerland 2002 {published data only}
- Sauerland S, Neugebauer EAM. An experiment of mailing physician surveys on two different issues in joint or separate mail. Journal of Clinical Epidemiology 2002;55:1046-8. [DOI] [PubMed] [Google Scholar]
Schmidt 2005 {published data only}
- Schmidt JB, Calantone RJ, Griffin A, Montoya-Weiss MM. Do certified mail third-wave follow-ups really boost response rates and quality? Marketing Letters 2005;16(2):129-41. [Google Scholar]
Schmuhl 2010 {published data only}
- Schmuhl P, Van Duker H, Gurley K L, Webster A, Olson L M. Reaching emergency medical services providers: is one survey mode better than another? Prehospital Emergency Care 2010;14(3):361-9. [DOI] [PubMed] [Google Scholar]
Schwartzenberger 2017 {published data only}
- Schwartzenberger Justin, Presson Angela, Lyle Adam, O'Farrell Andrew, Tyser Andrew R. Remote Collection of Patient-Reported Outcomes Following Outpatient Hand Surgery: A Randomized Trial of Telephone, Mail, and E-Mail. The Journal of hand surgery 2017;42(9):693-9. [DOI] [PubMed] [Google Scholar]
Schweitzer 1995 {published data only}
- Schweitzer M, Asch D. Timing payments to subjects of mail surveys: cost-effectiveness and bias. Journal of Clinical Epidemiology 1995;48(11):1325-9. [DOI] [PubMed] [Google Scholar]
Scott 1957 {published data only}
- Scott FG. Mail questionnaires used in a study of older women. Sociology and Social Research 1957;41:281-4. [Google Scholar]
Scott 2011 {published data only}
- Scott A, Jeon S H, Joyce C M, Humphreys J S, Kalb G, Witt J, et al. A randomised trial and economic evaluation of the effect of response mode on response rate, response bias, and item non-response in a survey of doctors. BMC MEDICAL RESEARCH METHODOLOGY 2011;11:126. [DOI] [PMC free article] [PubMed] [Google Scholar]
Sebo 2017 {published data only}
- Sebo P, Maisonneuve H, Cerutti B, Fournier JP, Senn N, Haller DM. Rates, Delays, and Completeness of General Practitioners' Responses to a Postal Versus Web-Based Survey: A Randomized Trial. JOURNAL OF MEDICAL INTERNET RESEARCH 2017;19(3):e83. [DOI] [PMC free article] [PubMed] [Google Scholar]
See Tai 1997 {published data only}
- See Tai S, Nazareth I, Haines A, Jowett C. A randomized trial of the impact of telephone and recorded delivery reminders on the response rate to research questionnaires. Journal of Public Health Medicine 1997;19(2):219-21. [DOI] [PubMed] [Google Scholar]
Severi 2011a {published data only}
- Severi E, Free C, Knight R, Robertson S, Edwards P, Hoile E. Two controlled trials to increase participant retention in a randomized controlled trial of mobile phone-based smoking cessation support in the United Kingdom. CLINICAL TRIALS 2011;8(5):654-60. [DOI] [PMC free article] [PubMed] [Google Scholar]
Severi 2011b {published data only}
- Severi E, Free C, Knight R, Robertson S, Edwards P, Hoile E. Two controlled trials to increase participant retention in a randomized controlled trial of mobile phone-based smoking cessation support in the United Kingdom. CLINICAL TRIALS 2011;8(5):654-60. [DOI] [PMC free article] [PubMed] [Google Scholar]
Shackleton 1980 {published data only}
- Shackleton VJ, Wild JM, Wolffe M. Screening optometric patients by questionnaire: methods of improving response. American Journal of Optometry and Physiological Optics 1980;57(6):404-6. [DOI] [PubMed] [Google Scholar]
Shah 2001 {published data only}
- Shah S, Harris TJ, Rink E, DeWilde S, Victor CR, Cook DG. Do income questions and seeking consent to link medical records reduce survey response rates? A randomised controlled trial among older people. British Journal of General Practice 2001;51:223-5. [PMC free article] [PubMed] [Google Scholar]
Shahar 1993 {published data only}
- Shahar E, Bisgard KM, Folsom AR. Response to mail surveys: effect of a request to explain refusal to participate. Epidemiology 1993;4:480-2. [PubMed] [Google Scholar]
Sharp 2006 {published data only}
- Sharp L, Cochran C, Cotton SC, Gray NM, Gallagher ME. Enclosing a pen with a postal questionnaire can significantly increase the response rate. Journal of Clinical Epidemiology 2006;59:747–54. [DOI] [PubMed] [Google Scholar]
Shaw 2001 {published data only}
- Shaw MJ, Beebe TJ, Jensen HL, Adlis SA. The use of monetary incentives in a community survey: Impact on response rates, data quality, and cost. Health Services Research 2001;35(6):1339-46. [PMC free article] [PubMed] [Google Scholar]
Sheikh 1982 {published data only}
- Sheikh K. Response to postal questionnaire: the effects of enquiry about earnings. International Review of Applied Psychology 1982;31:345-9. [Google Scholar]
Shin 1992 {unpublished data only}
- Shin E. An experimental study of techniques to improve response rates of mail questionnaire. Utah State University 1992.
Shiono 1991 {published data only}
- Shiono PH, Klebanoff MA. The effect of two mailing strategies on the response to a survey of physicians. American Journal of Epidemiology 1991;134(5):539-42. [DOI] [PubMed] [Google Scholar]
Signorelli 2021 {published data only}
- Signorelli Christina, Wakefield Claire E, McLoone Jordana K, Mateos Marion K, Aaronson Neil K, Lavoipierre Ange, et al. A cost-effective approach to increasing participation in patient-reported outcomes research in cancer: A randomized trial of video invitations. International journal of cancer 2021;148(4):971-80. [DOI] [PubMed] [Google Scholar]
Simon 1967a {published data only}
- Simon R. Responses to personal and form letters in mail surveys. Journal of Advertising Research 1967;7:28-30. [Google Scholar]
Simon 1967b {published data only}
- Simon R. Responses to personal and form letters in mail surveys. Journal of Advertising Research 1967;7:28-30. [Google Scholar]
Simon 1967c {published data only}
- Simon R. Responses to personal and form letters in mail surveys. Journal of Advertising Research 1967;7:28-30. [Google Scholar]
Sizmur 2019 {published data only}
- Sizmur Steve, Roth Firona. Testing interventions to improve response to a National Health Service Staff Survey. Health Services Management Research 2019;32(3):124-9. [DOI] [PubMed] [Google Scholar]
Skinner 1984 {published data only}
- Skinner SJ, Ferrell OC, Pride WM. Personal and nonpersonal incentives in mail surveys: immediate versus delayed inducements. Academy of Marketing Science 1984;12(1):106-14. [Google Scholar]
Sletto 1940 {published data only}
- Sletto R. Pretesting of questionnaires. American Sociological Review 1940;5:193-200. [Google Scholar]
Sloan 1997 {published data only}
- Sloan M, Kreiger N, James B. Improving response rates among doctors: randomised trial. BMJ 1997;315:1136. [DOI] [PMC free article] [PubMed] [Google Scholar]
Smith 1985 {published data only}
- Smith WCS, Crombie IK, Campion PD, Knox JDE. Comparison of response rates to a postal questionnaire from a general practice and a research unit. British Medical Journal 1985;291:1483-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
So 2018 {published data only}
- So R, Shinohara K, Aoki T, Tsujimoto Y, Suganuma A M, Furukawa T A. Effect of Recruitment Methods on Response Rate in a Web-Based Study for Primary Care Physicians: Factorial Randomized Controlled Trial. JOURNAL OF MEDICAL INTERNET RESEARCH 2018;20(2):e28. [DOI] [PMC free article] [PubMed] [Google Scholar]
Solnick 2020 {published data only}
- Solnick Rachel, Nogee Daniel P, Boatright Dowin H, Jarou Zach. The effect of monetary incentives on survey completion by emergency medicine trainees: A randomized trial. Academic Emergency Medicine 2020;27(Supplement 1):S198-9. [Google Scholar]
Spry 1989a {published data only}
- Spry VM, Hovell MF, Sallis JG, Hofsteter CR, Elder JP, Molgaard CA. Recruiting survey respondents to mailed surveys: controlled trials of incentives and prompts. American Journal of Epidemiology 1989;130(1):166-72. [DOI] [PubMed] [Google Scholar]
Spry 1989b {published data only}
- Spry VM, Hovell MF, Sallis JG, Hofsteter CR, Elder JP, Molgaard CA. Recruiting survey respondents to mailed surveys: controlled trials of incentives and prompts. American Journal of Epidemiology 1989;130(1):166-72. [DOI] [PubMed] [Google Scholar]
Spry 1989c {published data only}
- Spry VM, Hovell MF, Sallis JG, Hofsteter CR, Elder JP, Molgaard CA. Recruiting survey respondents to mailed surveys: controlled trials of incentives and prompts. American Journal of Epidemiology 1989;130(1):166-72. [DOI] [PubMed] [Google Scholar]
Stafford 1966 {published data only}
- Stafford JE. Influence of preliminary contact on mail returns. Journal of Marketing Research 1966;3:410-1. [Google Scholar]
Stange 2011 {published data only}
- Stange J P, Zyzanski S J. The Effect of a College Pen Incentive on Survey Response Rate Among Recent College Graduates. EVALUATION REVIEW 2011;35(1):93-9. [DOI] [PubMed] [Google Scholar]
Stapulonis 2004 {published data only}
- Stapulonis RA, Marsh S, Markesich J. Incentives with low-income populations: an experiment with merchant point-of-sale (POS) cards. Paper presented at the Annual Conference of the American Association for Public Opinion Research, Phoenix, Arizona 2004.
Starr 2015 {published data only}
- Starr K, McPherson G, Forrest M, Cotton SC. SMS text pre-notification and delivery of reminder e-mails to increase response rates to postal questionnaires: A factorial design, randomised, controlled trial. Trials 2015;8(16):295. [DOI] [PMC free article] [PubMed] [Google Scholar]
Stem 1984a {published data only}
- Stem DE, Steinhorst RK. Telephone interview and mail questionnaire applications of the randomized response model. Journal of the American Statistical Association 1984a;79(387):555-64. [Google Scholar]
Stem 1984b {published data only}
- Stem DE, Steinhorst RK. Telephone interview and mail questionnaire applications of the randomized response model. Journal of the American Statistical Association 1984a;79(387):555-64. [Google Scholar]
Stevens 1975 {published data only}
- Stevens RE. Does precoding mail questionnaires affect response rates. Public Opinion Quarterly 1975;38:621-2. [Google Scholar]
Stolzmann 2019 {published data only}
- Stolzmann K, Meterko M, Miller C J, Belanger L, Seibert M N, Bauer M S. Survey Response Rate and Quality in a Mental Health Clinic Population: Results from a Randomized Survey Comparison. JOURNAL OF BEHAVIORAL HEALTH SERVICES & RESEARCH 2019;46(3):521-32. [DOI] [PubMed] [Google Scholar]
Streiff 2001 {published data only}
- Streiff MB, Dundes L, Spivak JL. A mail survey of United States hematologists and oncologists: a comparison of business reply versus stamped return envelopes. Journal of Clinical Epidemiology 2001;54:430-2. [DOI] [PubMed] [Google Scholar]
Subar 2001 {published data only}
- Subar AF, Ziegler RG, Thompson FE, Johnson CC, Weissfeld JL, Reding D, et al. Is shorter always better? Relative importance of questionnaire length and cognitive ease on response rates and data quality for two dietary questionnaires. American Journal of Epidemiology 2001;153:404-9. [DOI] [PubMed] [Google Scholar]
Sutton 1992 {published data only}
- Sutton RJ, Zeitz LL. Multiple prior notifications, personalization, and reminder surveys. Marketing Research 1992;4:14-21. [Google Scholar]
Suzer‐Gurtekin 2019 {published data only}
- Suzer-Gurtekin Z T, Elkasabi M, Lepkowski J M, Liu M, Curtin R. Randomized experiments for web-mail surveys conducted using address-based samples of the general population. In: Experimental Methods in Survey Research: Techniques that Combine Random Sampling with Random Assignment. Wiley, 2019:275-89. [Google Scholar]
Svensson 2012 {published data only}
- Svensson M, Svensson T, Hansen A W, Lagerros Y T. The effect of reminders in a web-based intervention study. EUROPEAN JOURNAL OF EPIDEMIOLOGY 2012;27(5):333-40. [DOI] [PubMed] [Google Scholar]
Svoboda 2001 {unpublished data only}
- Svoboda P. A comparison of two questionnaires for assessing outcome after head injury in the Czech Republic. unpublished.
Swan 1980 {published data only}
- Swan JE, Epley DE, Burns WL. Can follow-up response rates to a mail survey be increased by including another copy of the questionnaire? Psychological Reports 1980;47:103-6. [Google Scholar]
Szelényi 2005 {published data only}
- Szelényi Katalin, Bryant Alyssa N, Lindholm Jennifer A. What Money Can Buy: Examining the effects of prepaid monetary incentives on survey response rates among college students. Educational Research and Evaluation 2005;11(4):385-404. [Google Scholar]
Szirony 2002 {published data only}
- Szirony TA, Price JH, Telljohann SK, Wolfe E. Survey return rates using a covering letter signed by a graduate student or faculty member. Psychological Reports 2002;91:1174-6. [DOI] [PubMed] [Google Scholar]
Tai 2018 {published data only}
- Tai Xiaochen, Smith Alanna M, McGeer Allison J, Dubé Eve, Holness Dorothy Linn, Katz Kevin, et al. Comparison of response rates on invitation mode of a web-based survey on influenza vaccine adverse events among healthcare workers: a pilot study. BMC Medical Research Methodology 2018;18(1):N.PAG. [DOI] [PMC free article] [PubMed] [Google Scholar]
Tamayo‐Sarver 2004 {published data only}
- Tamayo-Sarver JH, Baker DW. Comparison of responses to a US 2 dollar bill versus a chance to win 250 US dollars in a mail survey of emergency physicians. Academic Emergency Medicine 2004;11(8):888-91. [DOI] [PubMed] [Google Scholar]
Tambor 1993 {published and unpublished data}
- Tambor ES, Chase GA, Faden RR, Geller G, Hofman KJ, Holtzman NA. Improving response rates through incentives and follow-up: the effect on a survey of physician's knowledge of genetics. American Journal of Public Health 1993;83:1599-603. [DOI] [PMC free article] [PubMed] [Google Scholar]
Tariq 2021 {published data only}
- Tariq M B, Jones M H, Strnad G, Sosic E, Spindler K P. A Last-Ditch Effort and Personalized Surgeon Letter Improves PROMs Follow-Up Rate in Sports Medicine Patients: A Crossover Randomized Controlled Trial. JOURNAL OF KNEE SURGERY 2021;34(02):130-6. [DOI] [PubMed] [Google Scholar]
Taylor 1998 {published data only}
- Taylor S, Lynn P. The effect of a preliminary notification letter on response to a postal survey of young people. The Journal of the Market Research Society 1998;40(2):165-73. [Google Scholar]
Taylor 2006 {published data only}
- Taylor KS, Counsell CE, Harris CE, Gordon JC, Fonseca SC, Lee AJ. In a randomized study of envelope and ink color, colored ink was found to increase the response rate to a postal questionnaire. Journal of Clinical Epidemiology 2006;59(12):1326-30. [DOI] [PubMed] [Google Scholar]
Taylor 2019 {published data only}
- Taylor Sara, Ferguson Craig, Peng Fengjiao, Schoeneich Magdalena, Picard Rosalind W. Use of In-Game Rewards to Motivate Daily Self-Report. JOURNAL OF MEDICAL INTERNET RESEARCH 2019;21(1):e11683. [DOI] [PMC free article] [PubMed] [Google Scholar]
Teisl 2005 {published data only}
- Teisl MF, Roe B, Vayda M. Incentive effects on response rates, data quality, and survey administration costs. International Journal of Public Opinion Research 2005;18(3):364-73. [Google Scholar]
Temple‐Smith 1998 {published data only}
- Temple-Smith M, Mulvey G, Doyle W. Maximising response rates in a survey of general practitioners - lessons from a Victorian survey on sexually transmissible diseases. Australian Family Physician 1998;27(Suppl 1):S15-8. [PubMed] [Google Scholar]
Thistlethwaite 1993 {published data only}
- Thistlethwaite PC. The impact of selected mail response enhancement techniques on surveys of the mature market: some new evidence. Journal of Professional Services Marketing 1993;8(2):269-76. [Google Scholar]
Thomson 2004 {published data only}
- Thomson CE, Paterson-Brown S, Russell D, McCaldin D, Russell IT. Short report: encouraging GPs to complete postal questionnaires - one big prize or many small prizes? A randomized controlled trial. Family Practice 2004;21(6):697-8. [DOI] [PubMed] [Google Scholar]
Tilbrook 2014 {published data only}
- Tilbrook HE, Becque T, Buckley H, MacPherson H, Bailey M, Torgerson DJ. Randomized trial within a trial of yellow 'post-it notes' did not improve questionnaire response rates among participants in a trial of treatments for neck pain. J Eval Clin Pract 2014;21(2):202‐204. [DOI] [PubMed] [Google Scholar]
Tjerbo 2005 {published data only}
- Tjerbo T, Kvaemer KJ, Botten G, Aasland OG. Bruk av incentiver for a oke svarandelen i sporreskjemaundersokelser. Tidsskr Nor Laegeforen 2005;18(125):2496-7. [PubMed] [Google Scholar]
Todd 2015 {published data only}
- Todd A L, Porter M, Williamson J L, Patterson J A, Roberts C L. Pre-notification letter type and response rate to a postal survey among women who have recently given birth. BMC MEDICAL RESEARCH METHODOLOGY 2015;15:104. [DOI] [PMC free article] [PubMed] [Google Scholar]
Trussell 2004a {published data only}
- Trussell N, Lavrakas PJ. The influence of incremental increases in token cash incentives on mail survey response. Public Opinion Quarterly 2004a;68(3):349-67. [Google Scholar]
Trussell 2004b {published data only}
- Trussell N, Lavrakas PJ. The influence of incremental increases in token cash incentives on mail survey response. Public Opinion Quarterly 2004b;68(3):349-67. [Google Scholar]
Trussell 2004c {published data only}
- Trussell N, Lavrakas PJ. The influence of incremental increases in token cash incentives on mail survey response. Public Opinion Quarterly 2004c;68(3):349-67. [Google Scholar]
Tullar 1979 {published data only}
- Tullar WL, Pressley MM, Gentry DL. Toward a theoretical framework for mail survey response. Proceeding of the Third Annual Conference of the Academy of Marketing Science 1979;2:243-7. [Google Scholar]
Tullar 2004 {published data only}
- Tullar JM, Katz JN, Wright EA, Fossel AH, Phillips CB, Maher NE, et al. Effect of handwritten, hand-stamped envelopes on response rate in a follow up study of hip replacement patients. Arthritis & Rheumatism 2004;51(3):501-4. [DOI] [PubMed] [Google Scholar]
Turnbull 2015 {published data only}
- Turnbull A E, O'Connor C L, Lau B, Halpern S D, Needham D M. Allowing Physicians to Choose the Value of Compensation for Participation in a Web-Based Survey: Randomized Controlled Trial. JOURNAL OF MEDICAL INTERNET RESEARCH 2015;17(7):e189. [DOI] [PMC free article] [PubMed] [Google Scholar]
Tuten 2004 {published data only}
- Tuten TL, Galesic M, Bosnjak M. Effects of immediate versus delayed notification of prize draw results on response behavior in web surveys: an experiment. Social Science Computer Review 2004;22:377-84. [Google Scholar]
Ulrich 2005 {published data only}
- Ulrich CM, Danis M, Koziol D, Garrett-Mayer E, Hubbard R, Grady C. Does it pay to pay? A randomized trial of prepaid financial incentives and lottery incentives in surveys of nonphysician healthcare professionals. Nursing Research 2005;54(3):178-83. [DOI] [PubMed] [Google Scholar]
Urban 1993 {published data only}
- Urban N, Anderson GL, Tseng A. Effects on response rates and costs of stamps vs business reply in a mail survey of physicians. Clinical Epidemiology 1993;46(5):455-9. [DOI] [PubMed] [Google Scholar]
van den Berg 2011 {published data only}
- Van den Berg MH, Overbeek A, Van der Pal HJ, Versluys AB, Bresters D, Van Leeuwen FE, et al. Using Web-Based and Paper-Based Questionnaires for Collecting Data on Fertility Issues Among Female Childhood Cancer Survivors: Differences in Response Characteristics. JOURNAL OF MEDICAL INTERNET RESEARCH 2011;13(3):e76. [DOI] [PMC free article] [PubMed] [Google Scholar]
van der Mark 2012 {published data only}
- Van der Mark Lonneke B, Van Wonderen Karina E, Mohrs Jacob, Bindels Patrick Je, Puhan Milo A, Ter Riet Gerben. The effect of two lottery-style incentives on response rates to postal questionnaires in a prospective cohort study in preschool children at high risk of asthma: a randomized trial. BMC Medical Research Methodology 2012;12(100968545):186. [DOI] [PMC free article] [PubMed] [Google Scholar]
VanGeest 2001 {published data only}
- VanGeest JB, Wynia MK, Cummins DS, Wilson IB. Effects of different monetary incentives on the return rate of a national mail survey of physicians. Medical Care 2001;39(2):197-201. [DOI] [PubMed] [Google Scholar]
Van Mol 2017 {published data only}
- Van Mol Christof. Improving web survey efficiency: the impact of an extra reminder and reminder content on web survey response. INTERNATIONAL JOURNAL OF SOCIAL RESEARCH METHODOLOGY 2017;20(4):317-27. [Google Scholar]
Veen 2015 {published data only}
- Veen Floris van, Göritz Anja S, Sattler Sebastian. Response Effects of Prenotification, Prepaid Cash, Prepaid Vouchers, and Postpaid Vouchers: An Experimental Comparison. SOCIAL SCIENCE COMPUTER REVIEW 2015;34(3):333-46. [Google Scholar]
Veiga 1974 {published data only}
- Veiga JF. Getting the mail questionnaire returned: Some practical research considerations. Journal of Applied Psychology 1974;59(2):217-8. [Google Scholar]
Viera 2012 {published data only}
- Viera Anthony J, Edwards Teresa. Does an offer for a free on-line continuing medical education (CME) activity increase physician survey response rate? A randomized trial. BMC research notes 2012;5(101462768):129. [DOI] [PMC free article] [PubMed] [Google Scholar]
Virtanen 2007a {published data only}
- Virtanen V, Sirkiä T, Jokiranta V. Reducing nonresponse by SMS reminders in mail surveys. Social Science Computer Review 2007a;25:384-95. [Google Scholar]
Virtanen 2007b {published data only}
- Virtanen V, Sirkiä T, Jokiranta V. Reducing nonresponse by SMS reminders in mail surveys. Social Science Computer Review 2007b;25:384-95. [Google Scholar]
Virtanen 2007c {published data only}
- Virtanen V, Sirkiä T, Jokiranta V. Reducing nonresponse by SMS reminders in mail surveys. Social Science Computer Review 2007c;25:384-95. [Google Scholar]
Vocino 1977 {published data only}
- Vocino T. Three variables in stimulating responses to mailed questionnaires. Journal of Marketing 1977;41:76-7. [Google Scholar]
Vogel 1992 {published data only}
- Vogel PA, Skjostad K, Eriksen L. Influencing return rate by mail of alcoholics' questionnaires at follow-up by varying lottery procedures and questionnaire lengths. Two experimental studies. European Journal of Psychiatry 1992;6(4):213-22. [Google Scholar]
VonRiesen 1979 {published data only}
- VonRiesen RD. Postcard reminders versus replacement questionnaires and mail survey response rates from a professional population. Journal of Business Research 1979;7:1-7. [Google Scholar]
Waisanen 1954 {published data only}
- Waisanen FB. A note on the response to a mailed questionnaire. Public Opinion Quarterly 1954;18:210-2. [Google Scholar]
Wakabayashi 2012 {published data only}
- Wakabayashi C, Hayashi K, Nagai K, Sakamoto N, Iwasaki Y. Effect of stamped reply envelopes and timing of newsletter delivery on response rates of mail survey: a randomised controlled trial in a prospective cohort study. BMJ OPEN 2012;2(5):e001181. [DOI] [PMC free article] [PubMed] [Google Scholar]
Walker 1997 {unpublished data only}
- Walker N on behalf of the Auckland Leg Ulcer Study Group. unpublished data only. Auckland Leg Ulcer Study - Trial data 1997-8.
Waltemyer 2005 {published data only}
- Waltemyer S, Sagas M, Cunningham GB, Jordan JS, Turner BA. The effects of personalization and colored paper on mailed questionnaire response rates in a coaching sample. Research Quarterly for Exercise and Sport 2005;76(1):A130. [Google Scholar]
Wan 2012 {published data only}
- Wan J, Abuabara K, Shin DB, Troxel AB, Bebo BF Jr, Gelfand JM. Dermatologist response rates to a mailed questionnaire: a randomized trial of monetary incentives. J Am Acad Dermatol 2012;66(1):e18-20. [DOI] [PMC free article] [PubMed]
Ward 1996 {published data only}
- Ward J, Boyle C, Long D, Ovadia C. Patient surveys in general practice. Australian Family Physician 1996;25(1):S19-S20. [PubMed] [Google Scholar]
Ward 1998 {published data only}
- Ward J, Bruce T, Holt P, D'Este K, Sladden M. Labour-saving strategies to maintain survey response rates: a randomised trial. Australian and New Zealand Journal of Public Health 1998;22(3 Suppl):394-6. [DOI] [PubMed] [Google Scholar]
Warriner 1996 {published and unpublished data}
- Warriner K, Goyder J, Gjertsen H, Hohner P, McSpurren K. Charities, no; lotteries, no; cash, yes. Public Opinion Quarterly 1996;60:542-62. [Google Scholar]
Warwick 2019 {published data only}
- Warwick H, Hutyra C, Politzer C, Francis A, Risoli T, Green C, et al. Small Social Incentives Did Not Improve the Survey Response Rate of Patients Who Underwent Orthopaedic Surgery: A Randomized Trial. CLINICAL ORTHOPAEDICS AND RELATED RESEARCH 2019;477(7):1648-56. [DOI] [PMC free article] [PubMed] [Google Scholar]
Weaver 2019 {published data only}
- Weaver Lesley, Beebe Timothy J, Rockwood Todd. The impact of survey mode on the response rate in a survey of the factors that influence Minnesota physicians' disclosure practices. BMC medical research methodology 2019;19(1):73. [DOI] [PMC free article] [PubMed] [Google Scholar]
Webborn 2022 {published data only}
- Webborn E, McKenna E, Elam S, Anderson B, Cooper A, Oreszczyn T. Increasing response rates and improving research design: Learnings from the Smart Energy Research Lab in the United Kingdom. ENERGY RESEARCH & SOCIAL SCIENCE 2022;83:102312. [Google Scholar]
Weilbacher 1952 {published data only}
- Weilbacher WM, Walsh HR. Mail questionnaires and the personalized letter of transmittal. Marketing Notes 1952;16:331-6. [Google Scholar]
Weir 1999 {unpublished data only}
- Weir N. Methods of following up stroke patients. Neurosciences Trials Unit, University of Edinburgh.
Wells 1984 {unpublished data only}
- Wells DV. The representativeness of mail questionnaires as a function or sponsorship, return postage, and time of response. Doctoral Dissertation 1984.
Weltzien 1986 {published data only}
- Weltzien RT, McIntyre TJ, Ernst JA, Walsh JA, Parker JK. Crossvalidation of some psychometric properties of the CSQ and its differential return rate as a function of token financial incentives. Community Mental Health Journal 1986;22(1):49-55. [DOI] [PubMed] [Google Scholar]
Wenemark 2010 {published data only}
- Wenemark M, Vernby A, Norberg A L. Can incentives undermine intrinsic motivation to participate in epidemiologic surveys? EUROPEAN JOURNAL OF EPIDEMIOLOGY 2010;25(4):231-5. [DOI] [PubMed] [Google Scholar]
Wensing 1999a {published data only}
- Wensing M, Mainz J, Kramme O, Jung HP, Ribacke M. Effect of mailed reminders on the response rate in surveys among patients in general practice. Journal of Clinical Epidemiology 1999;52(6):585-7. [DOI] [PubMed] [Google Scholar]
Wensing 1999b {published data only}
- Wensing M, Mainz J, Kramme O, Jung HP, Ribacke M. Effect of mailed reminders on the response rate in surveys among patients in general practice. Journal of Clinical Epidemiology 1999;52(6):585-7. [DOI] [PubMed] [Google Scholar]
Wensing 2005 {published data only}
- Wensing M, Schattenberg G. Initial nonresponders had an increased response rate after repeated questionnaire mailings. Journal of Clinical Epidemiology 2005;58:959–61. [DOI] [PubMed] [Google Scholar]
Whitcomb 2004 {published data only}
- Whitcomb ME, Porter SR. E-mail contacts: a test of complex graphical designs in survey research. Social Science Computer Review 2004;22:370-6. [Google Scholar]
White 1997 {published data only}
- White MB, Chambers KM. Type of cover letter and questionnaire color: do they influence the response rate in survey research with marriage and family therapists? Family Therapy 1997;24(1):19-24. [Google Scholar]
White 2005a {published data only}
- White E, Carney PA, Kolar AS. Increasing response to mailed questionnaires by including a pencil/pen. American Journal of Epidemiology 2005a;162(3):261-6. [DOI] [PubMed] [Google Scholar]
White 2005b {published data only}
- White E, Carney PA, Kolar AS. Increasing response to mailed questionnaires by including a pencil/pen. American Journal of Epidemiology 2005b;162(3):261-5. [DOI] [PubMed] [Google Scholar]
Whitehead 2011 {published data only}
- Whitehead Lisa. Methodological issues in Internet-mediated research: a randomized comparison of internet versus mailed questionnaires. Journal of medical Internet research 2011;13(4):e109. [DOI] [PMC free article] [PubMed] [Google Scholar]
Whiteman 2003 {published data only}
- Whiteman MK, Langenberg P, Kjerulff K, McCarter R, Flaws JA. A randomized trial of incentives to improve response rates to a mailed women's health questionnaire. Journal of Women's Health 2003;12(8):821-8. [DOI] [PubMed] [Google Scholar]
Whiteside 2019 {published data only}
- Whiteside Katie, Flett Lydia, Mitchell Alex, Fairhurst Caroline, Cockayne Sarah, Rodgers Sara, et al. Using pens as an incentive for trial recruitment of older adults: An embedded randomised controlled trial. F1000Research 2019;8(101594320):315. [DOI] [PMC free article] [PubMed] [Google Scholar]
Whitmore 1976 {published data only}
- Whitmore WJ. Mail survey premiums and response bias. Journal of Marketing Research 1976;13:46-50. [Google Scholar]
Wiant 2018 {published data only}
- Wiant Kristine, Geisen Emily, Creel Darryl, Willis Gordon, Freedman Andrew, de Moor Janet, et al. Risks and rewards of using prepaid vs. postpaid incentive checks on a survey of physicians. BMC medical research methodology 2018;18(1):104. [DOI] [PMC free article] [PubMed] [Google Scholar]
Willits 1995 {published data only}
- Willits FK, Ke B. Part-whole question order effects. Public Opinion Quarterly 1995;59:392-403. [Google Scholar]
Wilson 2010 {published data only}
- Wilson P M, Petticrew M, Calnan M, Nazareth I. Effects of a Financial Incentive on Health Researchers' Response to an Online Survey: a Randomized Controlled Trial. JOURNAL OF MEDICAL INTERNET RESEARCH 2010;12(2):e13. [DOI] [PMC free article] [PubMed] [Google Scholar]
Windsor 1992 {published data only}
- Windsor J. What can you ask about? The effect on response to a postal screen of asking about two potentially sensitive questions. Journal of Epidemiology and Community Health 1992;46:83-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Wiseman 1972 {published data only}
- Wiseman F. Methodological bias in public opinion surveys. Public Opinion Quarterly 1972;36:105-8. [Google Scholar]
Wiseman 1973 {published data only}
- Wiseman F. Factor interaction effects in mail survey response rates. Journal of Marketing Research 1973;10:330-3. [Google Scholar]
Wong 2021 {published data only}
- Wong HZ, Brusseleers M, Hall KA, Maiden MJ, Chapple LS, Chapman MJ, Hodgson CL, Gluck S. Mixed-mode versus paper surveys for patient-reported outcomes after critical illness: A randomised controlled trial. Australian Critical Care 2021;35(3):286-293. [DOI] [PubMed] [Google Scholar]
Woodward 1985 {published data only}
- Woodward A, Douglas B, Miles H. Chance of a free dinner increases response to mail questionnaire. International Journal of Epidemiology 1985;14:641-2. [DOI] [PubMed] [Google Scholar]
Woolf 2021 {published data only}
- Woolf B, Edwards P. Does pre-notification increase questionnaire response rates: a randomised controlled trial nested within a systematic review. BMC MEDICAL RESEARCH METHODOLOGY 2021;21(259):1-7. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Worthen 1985a {published data only}
- Worthen BR, Valcarce RW. Relative effectiveness of personalized and form covering letters in initial and follow-up mail surveys. Psychology Reports 1985;57:735-44. [Google Scholar]
Worthen 1985b {published data only}
- Worthen BR, Valcarce RW. Relative effectiveness of personalized and form covering letters in initial and follow-up mail surveys. Psychology Reports 1985;57:735-44. [Google Scholar]
Worthen 1985c {published data only}
- Worthen BR, Valcarce RW. Relative effectiveness of personalized and form covering letters in initial and follow-up mail surveys. Psychology Reports 1985;57:735-44. [Google Scholar]
Wotruba 1966 {published data only}
- Wotruba TR. Monetary inducements and mail questionnaire response. Journal of Marketing Research 1966;3:398-400. [Google Scholar]
Wright 1984 {unpublished data only}
- Wright SJ. Mail survey response rates: a test of four techniques designed to increase response rates and a discussion of the associated cost considerations. Student Research Report, Department of Marketing, Massey University 1984.
Wright 1995 {published data only}
- Wright M. The effect of pre-notification on mail survey response rates: an experimental result. Marketing Bulletin 1995;6:59-64. [Google Scholar]
Wunder 1988 {published data only}
- Wunder GC, Wynn GW. The effects of address personalisation on mailed questionnaires response rate, time and quality. Journal of the Market Research Society 1988;30(1):95-101. [Google Scholar]
Wynn 1985 {published data only}
- Wynn GW, McDaniel SW. The effect of alternative foot-in-the-door manipulations on mailed questionnaire response rate and quality. Journal of the Market Research Society 1985;27(1):15-26. [Google Scholar]
Xie 2013 {published data only}
- Xie Y J, Ho S C. Prenotification had no additional effect on the response rate and survey quality: a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2013;66(12):1422-6. [DOI] [PubMed] [Google Scholar]
Yetter 2010 {published data only}
- Yetter Georgette, Capaccioli Kristen. Differences in responses to Web and paper surveys among school professionals. Behavior research methods 2010;42(1):266-72. [DOI] [PubMed] [Google Scholar]
Young 2015 {published data only}
- Young J M, O'Halloran A, McAulay C, Pirotta M, Forsdike K, Stacey I, et al. Unconditional and conditional incentives differentially improved general practitioners' participation in an online survey: randomized controlled trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2015;68(6):693-7. [DOI] [PubMed] [Google Scholar]
Young 2020 {published data only}
- Young Ben, Bedford Laura, das Nair Roshan, Gallant Stephanie, Littleford Roberta, Robertson John F R, et al. Unconditional and conditional monetary incentives to increase response to mailed questionnaires: A randomized controlled study within a trial (SWAT). Journal of evaluation in clinical practice 2020;26(3):893-902. [DOI] [PubMed] [Google Scholar]
Yu 2017 {published data only}
- Yu S C, Alper H E, Nguyen A M, Brackbill R M, Turner L, Walker D J, et al. The effectiveness of a monetary incentive offer on survey response rates and response completeness in a longitudinal study. BMC MEDICAL RESEARCH METHODOLOGY 2017;17(1):77. [DOI] [PMC free article] [PubMed] [Google Scholar]
Ziegenfuss 2010 {published data only}
- Ziegenfuss Jeanette Y, Beebe Timothy J, Rey Enrique, Schleck Cathy, Locke G Richard III, Talley Nicholas J. Internet Option in a Mail Survey: More Harm Than Good? Epidemiology 2010;21(4):585-586. [DOI] [PubMed] [Google Scholar]
Ziegenfuss 2011 {published data only}
- Ziegenfuss Jeanette Y, Shah Nilay D, Deming James R, Van Houten Holly K, Smith Steven A, Beebe Timothy J. Offering results to participants in a diabetes survey: effects on survey response rates. The patient 2011;4(4):241-5. [DOI] [PubMed] [Google Scholar]
Ziegenfuss 2012 {published data only}
- Ziegenfuss J Y, Burmeister K, James K M, Haas L, Tilburt J C, Beebe T J. Getting physicians to open the survey: little evidence that an envelope teaser increases response rates. BMC MEDICAL RESEARCH METHODOLOGY 2012;12:41. [DOI] [PMC free article] [PubMed] [Google Scholar]
Ziegenfuss 2014 {published data only}
- Ziegenfuss J Y, Tilburt J C, Lackore K, Jenkins S, James K, Beebe T J. Envelope Type and Response Rates in a Survey of Health Professionals. FIELD METHODS 2014;26(4):380-9. [Google Scholar]
Zusman 1987 {published data only}
- Zusman BJ, Duby P. An evaluation of the use of monetary incentives in postsecondary survey research. Journal of Research and Development in Education 1987;20(4):73-8. [Google Scholar]
References to studies excluded from this review
Alcaraz 2020 {published data only}
- Alcaraz Kassandra I, Vereen Rhyan N, Burnham Donna. Use of Telephone and Digital Channels to Engage Socioeconomically Disadvantaged Adults in Health Disparities Research Within a Social Service Setting: Cross-Sectional Study.. Journal of Medical Internet Research 2020;22(4):N.PAG-N.PAG-N.PAG-N.PAG. [DOI: 10.2196/16680] [DOI] [PMC free article] [PubMed] [Google Scholar]
Alexander 2008a {published data only}
- Alexander Gwen L, Divine George W, Couper Mick P, McClure Jennifer B, Stopponi Melanie A, Fortman Kristine K, Tolsma Dennis D, Strecher Victor J, Johnson Christine Cole. Effect of incentives and mailing features on online health program enrollment.. American journal of preventive medicine 2008;34(5):382-8-382-8. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Allen 1980 {published data only}
- Allen CT. More on self-perception theory’s foot technique in the pre-call/mail survey setting. Journal of Marketing Research 1980;17:498-502. [Google Scholar]
Anderson 1975 {published data only}
- Anderson JF. Effects of response rates of formal and informal questionnaire follow-up techniques. Journal of Applied Psychology 1975;60(2):255-7. [Google Scholar]
Anderson 2007 {published data only}
- Anderson DA, Simmons AM, Milnes SM, Earleywine M. Effect of response format on endorsement of eating disordered attitudes and behaviors.. International Journal of Eating Disorders 2007;40(1):90-93-90-93. [DOI: 10.1002/eat.20342] [DOI] [PubMed] [Google Scholar]
Angus 2003 {published data only}
- Angus VC, Entwistle VA, Emslie MJ, Walker KA, Andrew JE. The requirement for prior consent to participate on survey response rates: a population-based survey in Grampian. BMC Health Services Research 2003;3(21):1-10. [DOI] [PMC free article] [PubMed] [Google Scholar]
Antoun 2020 {published data only}
- Antoun C, Cernat A. Factors Affecting Completion Times: A Comparative Analysis of Smartphone and PC Web Surveys. SOCIAL SCIENCE COMPUTER REVIEW 2020;38(4):477-489-477-489. [DOI: 10.1177/0894439318823703] [DOI] [Google Scholar]
Armstrong 1975 {published data only}
- Armstrong JS. Monetary incentives in mail surveys. Public Opinion Quarterly 1975;39:111-6. [Google Scholar]
Asch 1994 {published data only}
- Asch DA, Christakis NA. Different response rates in a trial of two envelope styles in mail survey research. Epidemiology 1994;5(3):364-5. [DOI] [PubMed] [Google Scholar]
Ash 1952 {published data only}
- Ash P. The effect of anonymity on attitude-questionnaire response. Journal of Abnormal and Social Psychology 1952;47:722-3. [DOI] [PubMed] [Google Scholar]
Baron 2001 {published data only}
- Baron G, De Wals P, Milord F. Cost-effectiveness of a lottery for increasing physicians' responses to a mail survey. Evaluation and the Health Professions 2001;24(1):47-52. [DOI] [PubMed] [Google Scholar]
Beaty 2018 {published data only}
- Beaty Brenda L, Brtnikova Michaela, Allison Mandy A, Kempe Allison, Crane Lori A, Hurley Laura P. A method for achieving high response rates in national surveys of U.S. primary care physicians. PLoS ONE 2018;13(8):e0202755-e0202755-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Becker 2019 {published data only}
- Becker Rolf, Moser Sara, Glauser David. Cash vs. vouchers vs. gifts in web surveys of a mature panel study--Main effects in a long-term incentives experiment across three panel waves. Social science research 2019;81((Becker, Moser, Glauser) University of Bern Department of Sociology of Education, Fabrikstrasse 8, Bern CH-3012, Switzerland):221-234-221-234. [DOI: ] [DOI] [PubMed] [Google Scholar]
Beebe 2011 {published data only}
- Beebe Timothy J, Ziegenfuss Jeanette Y, St Sauver Jennifer L, Jenkins Sarah M, Haas Lindsey, Davern Michael E, Talley Nicholas J. Health Insurance Portability and Accountability Act (HIPAA) authorization and survey nonresponse bias.. Medical care 2011;49(4):365-70-365-70. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Berthelot 1993 {published data only}
- Berthelot Jean-Marie, Latouche Michel. Improving the Efficiency of Data Collection: A Generic Respondent Follow-Up Strategy for Economic Surveys. Journal of Business and Economic Statistics 1993;11(4):417-24-417-24. [Google Scholar]
Bevis 1948 {published data only}
- Bevis JC. Economical incentive used for mail questionnaire. Public Opinion Quarterly 1948;12:492-3. [Google Scholar]
Beynon 2010 {published data only}
- Beynon Caryl M, Taylor Avril, Allen Elizabeth, Bellis Mark A. Visual versus written cues: a comparison of drug injectors' responses. Have surveys using the written word underestimated risk behaviors for hepatitis C? Substance use & misuse 2010;45(10):1491-1508-1491-1508. [DOI: ] [DOI] [PubMed] [Google Scholar]
Biggar 1992 {published data only}
- Biggar RJ, Melbye M. Responses to anonymous questionnaires concerning sexual behaviour: a method to examine potential biases. American Journal of Public Health 1992;82(11):1506-12. [DOI] [PMC free article] [PubMed] [Google Scholar]
Blumberg 1974 {published data only}
- Blumberg H, Fuller C, Hare AP. Response rates in postal surveys. Public Opinion Quarterly 1974;38:113-23. [Google Scholar]
Blumenfeld 1973 {published data only}
- Blumenfeld WS. Effect of appearance of correspondence on response rate to a mail questionnaire survey. Psychological Reports 1973;32:178. [Google Scholar]
Boucher 2015 {published data only}
- Boucher S, Gray A, Leong SL, Sharples H, Horwath C. Token monetary incentives improve mail survey response rates and participant retention: results from a large randomised prospective study of mid-age New Zealand women. NEW ZEALAND MEDICAL JOURNAL 2015;128(1413):20-30-20-30. [PubMed] [Google Scholar]
Brealey 2007 {published data only}
- Brealey SD, Atwell C, Bryan S, Coulton S, Cox H, Cross B, Fylan F, Garratt A, Gilbert FJ, Gillan MGC, Hendry M, Hood K, Houston H, King D, Morton V, Orchard J, Robling M, Russell IT, Torgerson D, Wadsworth V, Wilkinson C. Improving response rates using a monetary incentive for patient completion of questionnaires: an observational study. BMC MEDICAL RESEARCH METHODOLOGY 2007;7:12. [DOI: 10.1186/1471-2288-7-12] [DOI] [PMC free article] [PubMed] [Google Scholar]
Brechner 1976 {published data only}
- Brechner K, Shippee G, Obitz FW. Compliance techniques to increase mailed questionnaire return rates from alcoholics. Journal of Studies on Alcohol 1976;37(7):995-6. [DOI] [PubMed] [Google Scholar]
Breeman 2013 {published data only}
- Breeman Suzanne, Cotton Seonaidh, McDonald Alison, McPherson Gladys, MacLennan Graeme, Bruhn Hanne. Telephone calls to boost response rates in the collection of outcome data. Trials 2013;14(SUPPL. 1):207DUMMY-207DUMMY-. [Google Scholar]
Brennan 1958 {published data only}
- Brennan RD. Trading stamps as an incentive in mail surveys. Journal of Marketing 1958;22(3):306-7. [Google Scholar]
Brennan 1990 {published data only}
- Brennan M, Hoek J, Astridge C. The effects of monetary incentives on the response rate and cost-effectiveness of a mail survey. Journal of the Market Research Society 1990;33:229-41. [Google Scholar]
Burkhart 2021 {published data only}
- Burkhart Q, Orr Nate, Brown Julie A, Hays Ron D, Cleary Paul D, Beckett Megan K, Perry Suzanne E, Gaillot Sarah, Elliott Marc N. Associations of Mail Survey Length and Layout With Response Rates.. Medical Care Research & Review 2021;78(4):441-448-441-448. [DOI: 10.1177/1077558719888407] [DOI] [PubMed] [Google Scholar]
Cadilhac 2012 {published data only}
- Cadilhac DA, Lannin N, Lim J, Anderson C, Price C, Faux S, Levi C, Donnan GA. Randomised comparative efficiency of telephone versus mail follow-up in the Australian Stroke Clinical Registry (AuSCR). Cerebrovascular Diseases 2012;33(SUPPL. 2):21-21-. [DOI: ] [Google Scholar]
Callegaro 2010 {published data only}
- Callegaro Mario, McCutcheon Allan L, Ludwig Jack. Who's calling? The impact of caller ID on telephone survey response.. Field Methods 2010;22(2):175-191-175-191. [DOI: ] [Google Scholar]
Cartwright 1968 {published data only}
- Cartwright A, Ward AWM. Variations in general practitioners' response to postal questionnaires. British Journal of Preventive and Social Medicine 1968;22:199-205. [DOI] [PMC free article] [PubMed] [Google Scholar]
Cartwright 1989 {published data only}
- Cartwright A, Windsor J. Some further experiments with factors that might affect the response to postal questionnaires. Survey of Methodology Bulletin 1989;25:11-5. [Google Scholar]
Cernat 2018 {published data only}
- Cernat Alexandru, Lynn Peter. The role of e-mail communications in determining response rates and mode of participation in a mixed-mode design.. Field Methods 2018;30(1):70-87-70-87. [DOI: ] [Google Scholar]
Champion 1969 {published data only}
- Champion DJ, Sear AM. Questionnaire response rate: a methodological analysis. Social Forces 1969;47(3):335-9. [Google Scholar]
Chen 2016 {published data only}
- Chen Jane S, Sprague Brian L, Klabunde Carrie N, Tosteson Anna NA, Bitton Asaf, Onega Tracy, MacLean Charles D, Harris Kimberly, Schapira Marilyn M, Haas Jennifer S. Take the money and run? Redemption of a gift card incentive in a clinician survey.. BMC Medical Research Methodology 2016;16:1-5-1-5. [DOI: 10.1186/s12874-016-0126-2] [DOI] [PMC free article] [PubMed] [Google Scholar]
Cheung 2019 {published data only}
- Cheung Yee Tak Derek, Weng Xue, Wang Man Ping, Ho Sai Yin, Kwong Antonio Cho Shing, Lai Vienna Wai Yin, Lam Tai Hing. Effect of prepaid and promised financial incentive on follow-up survey response in cigarette smokers: a randomized controlled trial.. BMC medical research methodology 2019;19(1):138-138-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Childs 2005 {published data only}
- Childs LA, The Submacular Surgery Trials Research Group. Effect of order of administration of health-related quality of life interview instruments on responses. Quality of Life Research 2005;14:493–500. [DOI] [PubMed] [Google Scholar]
Chin 2015 {published data only}
- Chin WY, Choi EPH, Lam CLK. The effect of timing of incentive payments on response rates for cohort study telephone interviews in primary care setting with cost-minimization analysis, a randomized controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2015;15:79. [DOI: 10.1186/s12874-015-0073-3] [DOI] [PMC free article] [PubMed] [Google Scholar]
Choi 2017 {published data only}
- Seung Hee Choi, Mitchell Jason, Lipkus Isaac. Lessons Learned From an Online Study with Dual-smoker Couples.. American Journal of Health Behavior 2017;41(1):61-66-61-66. [DOI: 10.5993/AJHB.41.1.6] [DOI] [PubMed] [Google Scholar]
Chyou 2017 {published data only}
- Chyou PH, Schroeder D, Schwei K, Acharya A. Statistical Application and Cost Saving in a Dental Survey. CLINICAL MEDICINE & RESEARCH 2017;15(1-2):1-5-1-5. [DOI: 10.3121/cmr.2017.1323] [DOI] [PMC free article] [PubMed] [Google Scholar]
Clark 2008 {published data only}
- Clark Melissa A, Rogers Michelle L, Armstrong Gene F, Rakowski William, Kviz Frederick J. Differential response effects of data collection mode in a cancer screening study of unmarried women ages 40-75 years: a randomized trial.. BMC medical research methodology 2008;8(100968545):10-10-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Coleman 2021 {published data only}
- Coleman Elizabeth, Whitemore Rachel, Clark Laura, Daykin Karen, Clark Miranda. Pre-notification and personalisation of text messages to increase questionnaire completion in a smoking cessation pregnancy RCT: an embedded randomised factorial trial.. F1000Research 2021;10(101594320):637-637-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Coleman 2021a {published data only}
- Coleman Elizabeth, Whitemore Rachel, Clark Laura, Daykin Karen, Clark Miranda. Pre-notification and personalisation of text-messages to retain participants in a smoking cessation pregnancy RCT: an embedded randomised factorial trial.. F1000Research 2021;10(101594320):637-637-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Conrad 2007 {published data only}
- Conrad Frederick G, Schober Michael F, Coiner Tania. Bringing features of human dialogue to web surveys. Applied Cognitive Psychology 2007;21(2):165-187-165-187. [DOI: ] [Google Scholar]
Cook 1985 {published data only}
- Cook JR, Schoeps N, Kim S. Program responses to mail surveys as a function of monetary incentives. Psychological Reports 1985;57:366. [Google Scholar]
Dal Grande 2016 {published data only}
- Dal Grande Eleonora, Chittleborough Catherine Ruth, Campostrini Stefano, Dollard Maureen, Taylor Anne Winifred. Pre-Survey Text Messages (SMS) Improve Participation Rate in an Australian Mobile Telephone Survey: An Experimental Study.. PloS one 2016;11(2):e0150231-e0150231-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Desborough 2008 {published data only}
- Desborough JA, Butters P, Bhattacharya D, Holland RC, Wright DJ. Does it matter whether the recipient of patient questionnaires in general practice is the general practitioner or an independent researcher? The REPLY randomised trial. BMC MEDICAL RESEARCH METHODOLOGY 2008;8:42. [DOI: 10.1186/1471-2288-8-42] [DOI] [PMC free article] [PubMed] [Google Scholar]
Dillman 1972 {published data only}
- Dillman DA. Increasing mail questionnaire response in large samples of the general public. Public Opinion Quarterly 1972;36:254-7. [Google Scholar]
Down 2010 {published data only}
- Down Liz, Wade Julia, Neal David, Hamdy Freddie, Donovan Jenny, Lane JAthene. Factors influencing questionnaire response rates in trials. Clinical Trials 2010;7(4):460-460-. [DOI: ] [Google Scholar]
Drake 2014 {published data only}
- Drake Keith M, Hargraves J Lee, Lloyd Stephanie, Gallagher Patricia M, Cleary Paul D. The effect of response scale, administration mode, and format on responses to the CAHPS Clinician and Group survey.. Health services research 2014;49(4):1387-99-1387-99. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Drummond 2015 {published data only}
- Drummond F J, O'Leary E, Sharp L. Lottery ticket was more effective than a prize draw in increasing questionnaire response among cancer survivors. JOURNAL OF CLINICAL EPIDEMIOLOGY 2015;68(7):769-75. [DOI] [PubMed] [Google Scholar]
Duan 2007 {published data only}
- Duan Naihua, Alegria Margarita, Canino Glorisa, McGuire Thomas G, Takeuchi David. Survey conditioning in self-reported mental health service use: Randomized comparison of alternative instrument formats: Methods articles. Health Services Research 2007;42(2):890-907-890-907. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Duncan 2019 {published data only}
- Duncan Anne, Treweek Shaun, Goodman Kirsteen, Hagan Suzanne. Same intervention, different opinions: Some challenges of doing Study Within A Trial (SWAT) replication studies. Trials 2019;20(Supplement 1):PS1A. [DOI: ] [Google Scholar]
Dunlap 1950 {published data only}
- Dunlap JW. The effect of colour in direct mail advertising. Journal of Applied Psychology 1950;34:280-1. [DOI] [PubMed] [Google Scholar]
Eaton 2020 {published data only}
- Eaton Cyd, Comer Margaret, Pruette Cozumel, Psoter Kevin, Riekert Kristin. Text Messaging Adherence Intervention for Adolescents and Young Adults with Chronic Kidney Disease: Pilot Randomized Controlled Trial and Stakeholder Interviews.. Journal of medical Internet research 2020;22(8):e19861-e19861-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Ebert 2018 {published data only}
- Ebert Jonas Fynboe, Huibers Linda, Christensen Bo, Christensen Morten Bondo. Paper- or Web-Based Questionnaire Invitations as a Method for Data Collection: Cross-Sectional Comparative Study of Differences in Response Rate, Completeness of Data, and Financial Cost.. Journal of medical Internet research 2018;20(1):e24-e24-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Egeland 2017 {published data only}
- Egeland Merete T, Tarangen Magnus, Shiryaeva Olga, Gay Caryl, Dosen Liv K, Haye Rolf. Evaluation of strategies for increasing response rates to postal questionnaires in quality control of nasal septal surgery. BMC research notes 2017;10(1):189-189-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Eisinger 1974 {published data only}
- Eisinger RA, Janicki WP, Stevenson RL, Thompson WL. Increasing returns in international mail surveys. Public Opinion Quarterly 1974;38:126-30. [Google Scholar]
Elinson 1950 {published data only}
- Elinson J, Haines VT. Role of anonymity in attitude surveys. American Psychologist 1950;5:315. [Google Scholar]
Ettridge 2021 {published data only}
- Ettridge Kerry, Caruso Joanna, Roder David, Prichard Ivanka, Scharling-Gamba Katrine, Wright Kathleen, Miller Caroline. A randomised online experimental study to compare responses to brief and extended surveys of health-related quality of life and psychosocial outcomes among women with breast cancer.. Quality of Life Research 2021;30(2):407-423-407-423. [DOI: 10.1007/s11136-020-02651-x] [DOI] [PubMed] [Google Scholar]
Everett 1997 {published data only}
- Everett SA, Price JH, Bedell A, Telljohann SK. The effect of a monetary incentive in increasing the return rate of a survey to family physicians. Evaluation & the Health Professions 1997;20(2):207-14. [DOI] [PubMed] [Google Scholar]
Fang 2006 {published data only}
- Fang J, Shao P. Does material incentive really improve the response rate in web-based survey? A classification model of the potential respondents. International Conference on Management Science & Engineering (13th) 2006;1-3:74-7. [Google Scholar]
Fang 2012 {published data only}
- Fang Jiaming, Wen Chao, Pavur Robert. Participation Willingness in Web Surveys: Exploring Effect of Sponsoring Corporation's and Survey Provider's Reputation. Cyberpsychology, Behavior, and Social Networking 2012;15(4):195-199-195-199. [DOI: 10.1089/cyber.2011.0411] [DOI] [PMC free article] [PubMed] [Google Scholar]
Fang 2021 {published data only}
- Fang Heping, Xian Ruoling, Ma Zhuoying, Lu Mingyue, Hu Yan. Comparison of the differences between web-based and traditional questionnaire surveys in pediatrics: Comparative survey study. Journal of Medical Internet Research 2021;23(8):e30861-e30861-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Fernandez Lynch 2019 {published data only}
- Fernandez Lynch Holly, Joffe Steven, Thirumurthy Harsha, Xie Dawei, Largent Emily A. Association Between Financial Incentives and Participant Deception About Study Eligibility.. JAMA network open 2019;2(1):e187355-e187355-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Ferriss 1951 {published data only}
- Ferriss AL. A note on stimulating response to questionnaires. American Sociological Review 1951;16:247-9. [Google Scholar]
Fleming 2013 {published data only}
- Fleming Charles B, Marchesini Gina, Elgin Jenna, Haggerty Kevin P, Woodward Danielle, Abbott Robert D, Catalano Richard F. Use of Web and Phone Survey Modes to Gather Data From Adults About Their Young Adult Children: An Evaluation Based on a Randomized Design.. Field methods 2013;25(4):388-404-388-404. [DOI] [PMC free article] [PubMed] [Google Scholar]
Fu 2013 {published data only}
- Fu M, Martínez-Sánchez JM, Sureda X, Martínez C, Ballbè M, Baranda L, Riccobene A, Fernández E. Handwritten versus scanned signature on the invitation letter: does it make any difference in participation in a population-based study? Eur J Epidemiol. 2013;28(11):931-4. [DOI: 10.1007/s10654-013-9838-3] [DOI] [PubMed] [Google Scholar]
Furse 1981 {published data only}
- Furse DH, Stewart DW, Rados DL. Effects of foot-in-the-door, cash incentives, and follow-ups on survey response. Journal of Marketing Research 1981;18:473-8. [Google Scholar]
Gerace 1995 {published data only}
- Gerace TA, George VA, Arango IG. Response rates to six recruitment mailing formats and two messages about a nutrition program for women 50-79 years old. Controlled Clinical Trials 1995;16:422-31. [DOI] [PubMed] [Google Scholar]
Gibson 2020 {published data only}
- Gibson Anthony M, Bowling Nathan A. The effects of questionnaire length and behavioral consequences on careless responding.. European Journal of Psychological Assessment 2020;36(2):410-420-410-420. [DOI: ] [Google Scholar]
Gillespie 1975 {published data only}
- Gillespie DF, Perry RW. Survey return rates and questionnaire appearance. Australian and New Zealand Journal of Sociology 1975;11(3):71-2. [Google Scholar]
Gooden 2021 {published data only}
- Gooden Tiffany, Wright Alison, Swinn Eliza, Sizmur Steve. Optimising response rates in a national postal survey evaluating community mental health care: four interventions trialled. Journal of Mental Health 2021;32(1)((Gooden, Wright, Swinn, Sizmur) Picker Institute Europe, Oxford, United Kingdom):96-102. [DOI: ] [DOI] [PubMed] [Google Scholar]
Groves 2011 {published data only}
- Groves Robert M, Couper Mick P, Presser Stanley, Singer Eleanor, Tourangeau Roger, Acosta Giorgina Piani, Nelson Lindsay. "Experiments in producing nonresponse bias": Errata.. Public Opinion Quarterly 2011;75(4):819-819-. [Google Scholar]
Hansen 2004 {published data only}
- Hansen J, Alessandril PT, Croft ML, Burton PR, Klerk NH. The Western Australian register of childhood multiples: effects of questionnaire design and follow-up protocol on response rates and representativeness. Twin Research 2004;7(2):149-61. [DOI] [PubMed] [Google Scholar]
Hare 1998 {published data only}
- Hare S, Price JH, Flynn MG, King KA. Increasing return rates of a mail survey to exercise professionals using a modest monetary incentive. Perceptual and Motor Skills 1998;86:217-8. [DOI] [PubMed] [Google Scholar]
Harlow 1993 {published data only}
- Harlow BL. Telephone answering machines: the influence of leaving messages on telephone interviewing response rates. Epidemiology 1993;4(4):380-3. [PubMed] [Google Scholar]
Harrison 2019 {published data only}
- Harrison Siân, Henderson Jane, Alderdice Fiona, Quigley Maria A. Methods to increase response rates to a population-based maternity survey: a comparison of two pilot studies.. BMC Medical Research Methodology 2019;19(1):N.PAG-N.PAG-N.PAG-N.PAG. [DOI: 10.1186/s12874-019-0702-3] [DOI] [PMC free article] [PubMed] [Google Scholar]
Haugejorden 1987 {published and unpublished data}
- Haugejorden O, Nielsen WA. Experimental study of two methods of data collection by questionnaire. Community Dentistry & Oral Epidemiology 1987;15:205-8. [DOI] [PubMed] [Google Scholar]
Hawes 1987 {published data only}
- Hawes JM, Crittenden VL, Crittenden WF. The effects of personalisation, source, and offer on mail survey response rate and speed. Akron Business and Economic Review 1987;18:54-63. [Google Scholar]
Heads 1966 {published data only}
- Heads J, Thrift HJ. Notes on a study in postal response rates. Commentary 1966;8(4):257-62. [Google Scholar]
Heje 2006 {published data only}
- Heje NH, Vedsted P, Olesen F. A cluster-randomized trial of the significance of a reminder procedure in a patient evaluation survey in general practice. International Journal for Quality in Health Care 2006;18(3):232–7. [DOI] [PubMed] [Google Scholar]
Helgeson 2002 {published data only}
- Helgeson JG, Voss KE, Terpening WD. Determinants of mail-survey response: survey design factors and respondent factors. Psychology & Marketing 2002;19(3):303-28. [Google Scholar]
Hennrich 2021 {published data only}
- Hennrich P, Arnold C, Wensing M. Effects of personalized invitation letters on research participation among general practitioners: a randomized trial. BMC MEDICAL RESEARCH METHODOLOGY 2021;21(1):247. [DOI: 10.1186/s12874-021-01447-y] [DOI] [PMC free article] [PubMed] [Google Scholar]
Hing 2005 {published data only}
- Hing E, Schappert SM, Burt CW, Shimizu IM. Effects of form length and item format on response patterns and estimates of physician office and hospital outpatient department visits. Vital Health Statistics 2005;2(139):1-32. [PubMed] [Google Scholar]
Hinrichs 1975 {published data only}
- Hinrichs JR. Factors related to survey response rates: effects of sampling, follow up letters, and commitment to participation on mail attitude survey response. Journal of Applied Psychology 1975;60(2):249-51. [Google Scholar]
Hocking 2006 {published data only}
- Hocking JS, Lim MSC, Read T, Hellard M. Postal surveys of physicians gave superior response rates over telephone interviews in a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2006;59(5):521-524-521-524. [DOI: 10.1016/j.jclinepi.2005.10.009] [DOI] [PubMed] [Google Scholar]
Horevoorts 2015 {published data only}
- Horevoorts Nicole Je, Vissers Pauline Aj, Mols Floortje, Thong Melissa Sy, de Poll-Franse Lonneke V. Response rates for patient-reported outcomes using web-based versus paper questionnaires: comparison of two invitational methods in older colorectal cancer patients.. Journal of medical Internet research 2015;17(5):e111-e111-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Hsu 2017 {published data only}
- Hsu Joanne W, Schmeiser Maximilian D, Haggerty Catherine, Nelson Shannon. The effect of large monetary incentives on survey completion: Evidence from a randomized experiment with the Survey of Consumer Finances.. Public Opinion Quarterly 2017;81(3):736-747-736-747. [DOI: ] [Google Scholar]
Hughes 1989 {published data only}
- Hughes JR. Free reprints to increase the return of follow-up questionnaires. Controlled Clinical Trials 1989;10:352. [Google Scholar]
Hurd 2017 {published data only}
- Hurd Madeleine, Linsell Louise, Juszczak Ed, Hewer Oliver, Bowler Ursula, Johnson Samantha, Dorling Jon. Increasing follow-up response among parents of very preterm infants: Personalised contact, external promotion, and web-based questionnaires. Trials 2017;18(Supplement 1):P301. [DOI: ] [Google Scholar]
Hurd 2019 {published data only}
- Hurd Madeleine, Bowler Ursula, Juszczak Ed, Hewer Oliver, Dorling Jon, Johnson Samantha. Managing follow-up among parents of very pre-term infants: Methods to improve questionnaire response rate. Trials 2019;20(Supplement 1):181. [DOI: ] [Google Scholar]
ISRCTN16437731 2016 {published data only}
- ISRCTN16437731. Question-behavior effect and flu vaccination in the over 65s. ISRCTN registry 2016. [DOI: ]
Ives 1990 {published data only}
- Ives D, Traven N, Kuller L. Comparison of recruitment strategies for health promotion and disease prevalence in the elderly. American Journal of Epidemiology 1990;132:790. [Google Scholar]
Jacobson 2016 {published data only}
- Jacobson Amanda E, Vesely Sara K, Christian-Rancy Myra, O'Brien Sarah H. Mobile application vs. Paper pictorial blood assessment chart to track menses in young women: A randomized cross-over design. Blood 2016;128(22):1006. [DOI] [PubMed] [Google Scholar]
Jiang 2005 {published data only}
- Jiang P, Rosenbloom B. Customer intention to return online: price perception, attribute-level performance, and satisfaction unfolding over time. European Journal of Marketing 2005;39(1-2):150-74. [Google Scholar]
Jobber 2004 {published data only}
- Jobber David, Saunders John, Mitchell Vince-Wayne. Prepaid monetary incentive effects on mail survey response. Journal of Business Research 2004;57(4):347-350-347-350. [DOI: ] [Google Scholar]
Johnson 2014 {published data only}
- Johnson Samantha, Seaton Sarah E, Manktelow Bradley N, Smith Lucy K, Field David, Draper Elizabeth S, Marlow Neil, Boyle Elaine M. Telephone interviews and online questionnaires can be used to improve neurodevelopmental follow-up rates. BMC research notes 2014;7((Johnson, Seaton, Manktelow, Smith, Field, Draper, Marlow, Boyle) Department of Health Sciences, University of Leicester, 22-28 Princess Road West, Leicester LE1 6TP, UK. sjj19@le.ac.uk):219-219-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Johnson 2015 {published data only}
- Johnson Natalie A, Kypri Kypros, Latter Joanna, McElduff Patrick, Attia John, Saitz Richard, Saunders John B, Wolfenden Luke, Dunlop Adrian, Doran Christopher, McCambridge Jim. Effect of telephone follow-up on retention and balance in an alcohol intervention trial.. Preventive medicine reports 2015;2(101643766):746-9-746-9. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Kato 2021 {published data only}
- Kato T, Miura T. The impact of questionnaire length on the accuracy rate of online surveys. Journal of Marketing Analytics 2021;9(2):83-98-83-98. [DOI: 10.1057/s41270-021-00105-y] [DOI] [Google Scholar]
Kerin 1974 {published data only}
- Kerin RA. Personalization strategies, response rate and response quality in a mail survey. Social Science Quarterly 1974;55:175-81. [Google Scholar]
Kerin 1977 {published data only}
- Kerin RA, Peterson RA. Personalization, respondent anonymity, and response distortion in mail surveys. Journal of Applied Psychology 1977;62(1):86-9. [Google Scholar]
Kerin 1983 {published data only}
- Kerin RA. Effects of preliminary contacts on volunteering in mail surveys: another view. Perceptual and Motor Skills 1983;57:1282. [Google Scholar]
Kimball 1961 {published data only}
- Kimball AE. Increasing the rate of return in mail surveys. Journal of Marketing 1961;25:63-5. [Google Scholar]
Kimel 2010 {published data only}
- Kimel Miriam, McCormak J, Chen W, Brunt K, Runken Michael. A Comparative Trial of Paper-and-Pencil Versus Electronic Administration of the Patient Perception of Migraine Questionnaire-Revised (PPMQ-R). In: 52nd Annual Scientific Meeting of the American-Headache-Society Volume: 50. 2010.
Koetsenruijter 2015 {published data only}
- Koetsenruijter J, Lieshout J, Wensing M. Higher monetary incentives led to a lowered response rate in ambulatory patients: a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2015;68(11):1380-1382-1380-1382. [DOI: 10.1016/j.jclinepi.2015.03.018] [DOI] [PubMed] [Google Scholar]
Kundig 2011 {published data only}
- Kundig F, Staines A, Kinge T, Perneger TV. Numbering questionnaires had no impact on the response rate and only a slight influence on the response content of a patient safety culture survey: a randomized trial. JOURNAL OF CLINICAL EPIDEMIOLOGY 2011;64(11):1262-1265-1262-1265. [DOI: 10.1016/j.jclinepi.2011.02.008] [DOI] [PubMed] [Google Scholar]
Labovitz 2017 {published data only}
- Labovitz Jonathan, Patel Neil, Santander Israel. Web-Based Patient Experience Surveys to Enhance Response Rates A Prospective Study.. Journal of the American Podiatric Medical Association 2017;107(6):516-521-516-521. [DOI: ] [DOI] [PubMed] [Google Scholar]
Lane 2011 {published data only}
- Lane Athene J, Down Liz, Wade Julia, Donovan Jenny, Neal David, Hamdy Freddie. Understanding factors influencing questionnaire response rates to maximise retention in a long term complex intervention trial. Trials 2011;12(SUPPL. 1):A134. [DOI: ] [Google Scholar]
Lane 2017 {published data only}
- Lane Athene, Davis Michael, Wade Julia, Turner Emma, Walsh Eleanor, Metcalfe Chris, Martin Richard, Holding Peter, Bonnington Sue, Neal David. Maximising participant retention and outcome data in a long term cancer trial (protect). Trials 2017;18(Supplement 1):P185. [DOI: ] [Google Scholar]
Lapane 2007 {published data only}
- Lapane KL, Quilliam BJ, Hughes CM. A comparison of two distribution methods on response rates to a patient safety questionnaire in nursing homes. JOURNAL OF THE AMERICAN MEDICAL DIRECTORS ASSOCIATION 2007;8(7):446-452-446-452. [DOI: 10.1016/j.jamda.2007.04.007] [DOI] [PubMed] [Google Scholar]
Larsson 1970 {published data only}
- Larsson I. Increasing the rate of returns in mail surveys. A methodological study. Didakometry & Sociometry 1970;2:43-70. [Google Scholar]
Lavender 2009 {published data only}
- Lavender JM, Anderson DA. Effect of perceived anonymity in assessments of eating disordered behaviors and attitudes.. International Journal of Eating Disorders 2009;42(6):546-551-546-551. [DOI: 10.1002/eat.20645] [DOI] [PubMed] [Google Scholar]
Leece 2004a {published data only}
- Leece P. Correction and republication: Internet versus mailed questionnaires: A controlled [correction of "Randomized"] - Comparison (2) (vol 4, pg 6, 2004). JOURNAL OF MEDICAL INTERNET RESEARCH 2004;6(4):85-93-85-93. [Google Scholar]
Li 2015 {published data only}
- Li Y, Wang W, Wu Q, Velthoven MH, Chen L, Du XZ, Zhang YF, Rudan I, Car J. Increasing the response rate of text messaging data collection: a delayed randomized controlled trial. JOURNAL OF THE AMERICAN MEDICAL INFORMATICS ASSOCIATION 2015;22(1):51-64-51-64. [DOI: 10.1136/amiajnl-2014-002845] [DOI] [PMC free article] [PubMed] [Google Scholar]
Lim 2020 {published data only}
- Lim Stephanie L, Yang Jui-Chen, Ehrisman Jessie, Havrilesky Laura J, Reed Shelby D. Are Videos or Text Better for Describing Attributes in Stated-Preference Surveys?.. The patient 2020;13(4):401-408-401-408. [DOI: ] [DOI] [PubMed] [Google Scholar]
Liu 2011 {published data only}
- Liu S T, Geidenberger C. Comparing Incentives to Increase Response Rates Among African Americans in the Ohio Pregnancy Risk Assessment Monitoring System. MATERNAL AND CHILD HEALTH JOURNAL 2011;15(4):527-33. [DOI] [PubMed] [Google Scholar]
Longworth 1953 {published data only}
- Longworth DS. Use of a mail questionnaire. American Sociologist 1953;18:310-3. [Google Scholar]
Lopez‐ Cano 2007 {published data only}
- Lopez-Cano M, Vilallonga R, Sanchez JL, Hermosilla E, Armengol M. Short postal questionnaire and selective clinical examination combined with repeat mailing and telephone reminders as a method of follow-up in hernia surgery. Hernia 2007;11:397-402. [DOI] [PubMed] [Google Scholar]
Lund 1988 {published data only}
- Lund DB, Malhotra NK, Smith AE. Field validation study of conjoint analysis using selected mail survey response rate facilitators. Journal of Business Research 1988;16:351-68. [Google Scholar]
Malhotra 2008 {published data only}
- Malhotra N. COMPLETION TIME AND RESPONSE ORDER EFFECTS IN WEB SURVEYS. PUBLIC OPINION QUARTERLY 2008;72(5):914-934-914-934. [DOI: 10.1093/poq/nfn050] [DOI] [Google Scholar]
Maloshonok 2016 {published data only}
- Maloshonok Natalia, Terentev Evgeniy. The impact of visual design and response formats on data quality in a web survey of MOOC students.. Computers in Human Behavior 2016;62:506-515-506-515. [DOI: 10.1016/j.chb.2016.04.025] [DOI] [Google Scholar]
Marks 1981 {published data only}
- Mark RB. A factorial experiment in stimulating response to mail surveys. In: American Marketing Association Educators Conference. Vol. 47. 1981:398-400.
May 1960 {published data only}
- May RC. What approach gets the best return in mail surveys? Industrial Marketing 1960;45:50-1. [Google Scholar]
McCree‐Hale 2010 {published data only}
- McCree-Hale Renicha, De La Cruz Natalie G, Montgomery Ann Elizabeth. Using downloadable songs from Apple iTunes as a novel incentive for college students participating in a Web-based follow-up survey. American journal of health promotion : AJHP 2010;25(2):119-121-119-121. [DOI] [PubMed] [Google Scholar]
McDermott 2003 {published data only}
- McDermott MM, Greenland P, Hahn EA, Brogan D, Cella D, Ockene J, Pet al. The effects of continuing medical education credits on physician response rates to a mailed questionnaire. Health Marketing Quarterly 2003;20(4):27-42. [DOI] [PubMed] [Google Scholar]
McDermott 2018 {published data only}
- McDermott L, Cornelius V, Wright AJ, Burgess C, Forster AS, Ashworth M, Khoshaba B, Clery P, Fuller F, Miller J, Dodhia H, Rudisill C, Conner MT, Gulliford MC. Enhanced Invitations Using the Question-Behavior Effect and Financial Incentives to Promote Health Check Uptake in Primary Care. ANNALS OF BEHAVIORAL MEDICINE 2018;52(7):594-605-594-605. [DOI: 10.1093/abm/kax048] [DOI] [PMC free article] [PubMed] [Google Scholar]
Mehta 1995 {published data only}
- Mehta R, Sivadas E. Comparing response rates and response content in mail versus electronic mail surveys. Journal of the Market Research Society 1995;37:429-39. [Google Scholar]
Millar 2021 {published data only}
- Millar MM, Olson LM, VanBuren JM, Richards R, Pollack MM, Holubkov R, Berg RA, Carcillo JA, McQuillen PS, Meert KL, Mourani PM, Burd RS. Incentive delivery timing and follow-up survey completion in a prospective cohort study of injured children: a randomized experiment comparing prepaid and postpaid incentives. BMC MEDICAL RESEARCH METHODOLOGY 2021;21(1):233. [DOI: 10.1186/s12874-021-01421-8] [DOI] [PMC free article] [PubMed] [Google Scholar]
Murdoch 2010 {published data only}
- Murdoch Maureen, Pietila Diane M, Partin Melissa R. Randomized trial showed that an "embedded" survey strategy optimized authorization rates compared with two "after survey" strategies in veterans with PTSD.. Journal of clinical epidemiology 2010;63(6):665-71-665-71. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Myers 2007 {published data only}
- Myers RP, Shaheen AAM, Lee SS. Impact of pharmaceutical industry versus university sponsorship on survey response: A randomized trial among Canadian hepatitis C care providers. CANADIAN JOURNAL OF GASTROENTEROLOGY 2007;21(3):169-175-169-175. [DOI: 10.1155/2007/945630] [DOI] [PMC free article] [PubMed] [Google Scholar]
Neve 2021 {published data only}
- Neve OM, Benthem PPG, Stiggelbout AM, Hensen EF. Response rate of patient reported outcomes: the delivery method matters. BMC MEDICAL RESEARCH METHODOLOGY 2021;21(1):220. [DOI: 10.1186/s12874-021-01419-2] [DOI] [PMC free article] [PubMed] [Google Scholar]
Nitecki 1975 {published data only}
- Nitecki DA. Effects of sponsorship and nonmonetary incentive on response rate. Journalism Quarterly 1975;55:581-3. [Google Scholar]
Nitikman 2015 {published data only}
- Nitikman M, Mulpuri K, Reilly C. Paper versus internet administration of questionnaires in an adolescent idiopathic scoliosis population: A randomized crossover study. Journal of Investigative Medicine 2015;63(1):198-198-. [DOI: ] [Google Scholar]
Nitikman 2017 {published data only}
- Nitikman M, Mulpuri K, Reilly CW. Internet-administered Health-related Quality of Life Questionnaires Compared With Pen and Paper in an Adolescent Scoliosis Population: A Randomized Crossover Study. JOURNAL OF PEDIATRIC ORTHOPAEDICS 2017;37(2):E75-E79-E75-E79. [DOI] [PubMed] [Google Scholar]
Nord 2007 {published data only}
- Nord Mark, Hopwood Heather. Does interview mode matter for food security measurement? Telephone versus in-person interviews in the Current Population Survey Food Security Supplement. Public Health Nutrition 2007;10(12):1474-1480-1474-1480. [DOI: ] [DOI] [PubMed] [Google Scholar]
O'Toole 2008 {published data only}
- O'Toole Joanne, Sinclair Martha, Leder Karin. Maximising response rates in household telephone surveys.. BMC medical research methodology 2008;8(100968545):71-71-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Oden 1999 {published data only}
- Oden L, Price JH. Effects of a small monetary incentive and follow-up mailings on return rates of a survey to nurse practitioners. Psychological Reports 1999;85:1154-6. [DOI] [PubMed] [Google Scholar]
Onoye 2012 {published data only}
- Onoye Jane M, Goebert Deborah A, Nishimura Stephanie T. Use of incentives and web-based administration for surveying student alcohol and substance use in an ethnically diverse sample. Journal of Substance Use 2012;17(1):61-71-61-71. [DOI: ] [Google Scholar]
Otzen 2020 {published data only}
- Otzen Tamara, Fuentes Natalia, Wetzel Gustavo, Henríquez Constanza, Antúnez Zayra, Melnik Tamara. Suicidabilidad y apoyo social percibido en estudiantes universitarios con enfermedades crónicas no transmisibles. Ter. psicol 2020;38(1):119-129-119-129. [DOI: 10.4067/S0718-48082020000100119] [DOI] [Google Scholar]
Palmer 2018 {published data only}
- Palmer Cristina, Farhan Bilal, Nguyen Nobel, Zhang Lishi, Do Rebecca, Nguyen Danh V, Ghoniem Gamal. Are Electronic and Paper Questionnaires Equivalent to Assess Patients with Overactive Bladder?.. The Journal of urology 2018;200(2):369-374-369-374. [DOI: ] [DOI] [PubMed] [Google Scholar]
Pariyo 2019 {published data only}
- Pariyo George W, Greenleaf Abigail R, Gibson Dustin G, Ali Joseph, Selig Hannah, Labrique Alain B, Al Kibria Gulam Muhammed, Khan Iqbal Ansary, Masanja Honorati, Flora Meerjady Sabrina, Ahmed Saifuddin, Hyder Adnan A. Does mobile phone survey method matter? Reliability of computer-assisted telephone interviews and interactive voice response non-communicable diseases risk factor surveys in low and middle income countries.. PloS one 2019;14(4):e0214450-e0214450-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Perneger 2003 {published data only}
- Perneger TV, Kossovsky MP, Cathieni F, Florio VD, Burnand B. A randomized trial of four patient satisfaction questionnaires. Medical Care 2003;41(12):1343–52. [DOI] [PubMed] [Google Scholar]
Perneger 2014 {published data only}
- Perneger TV, Cullati S, Rudaz S, Agoritsas T, Schmidt RE, Combescure C, Courvoisier DS. Effect of numbering of return envelopes on participation, explicit refusals, and bias: experiment and meta-analysis. BMC MEDICAL RESEARCH METHODOLOGY 2014;14:6. [DOI: 10.1186/1471-2288-14-6] [DOI] [PMC free article] [PubMed] [Google Scholar]
Peytremann‐Bridevaux 2006a {published data only}
- Peytremann-Bridevaux I, Scherer F, Peer L, Cathieni F, Bonsack C, Cléopas A, et al. Satisfaction of patients hospitalised in psychiatric hospitals: a randomised comparison of two psychiatric-specific and one generic satisfaction questionnaires. BMC Health Services Research 2006;6(108):1-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Pieper 2018 {published data only}
- Pieper D, Kotte N, Ober P. The effect of a voucher incentive on a survey response rate in the clinical setting: a quasi-randomized controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2018;18:86. [DOI: 10.1186/s12874-018-0544-4] [DOI] [PMC free article] [PubMed] [Google Scholar]
Porter 2004 {published data only}
- Porter SR, Whitcomb ME. Understanding the effect of prizes on response rates. New Directions for Institutional Research 2004;121:51-62. [Google Scholar]
Pottick 1991 {published data only}
- Pottick KJ, Lerman P. Maximising survey response rates for hard-to-reach inner-city populations. Social Science Quarterly 1991;721:172-80. [Google Scholar]
Prado 2012 {published data only}
- Prado Cristiana Soares, Tenório Josceli Maria, Ruiz Evandro Eduardo Seron, Ortolani Cristina Lúcia Feijó, Pisa Ivan Torres. Impacto da utilização de mensagens do tipo SMS (Short Message Service) como lembrete na adesão ao tratamento de saúde: revisão sistemática da literatura. J. health inform 2012;4(4):159-64. [Google Scholar]
Rafiq 2016 {published data only}
- Rafiq M, Hussain Z, Akhtar S. Modifications of some simple one-stage randomized response models to two-stage in complex surveys. Pakistan Journal of Statistics and Operation Research 2016;12(2):327-338-327-338. [DOI: 10.18187/pjsor.v12i2.830] [DOI] [Google Scholar]
Rashidian 2008 {published data only}
- Rashidian A, Meulen J, Russell I. Differences in the contents of two randomized surveys of GPs' prescribing intentions affected response rates. JOURNAL OF CLINICAL EPIDEMIOLOGY 2008;61(7):718-721-718-721. [DOI: 10.1016/j.jclinepi.2007.10.019] [DOI] [PubMed] [Google Scholar]
Richards 2009 {published data only}
- Richards Julie, Ahrens Kym, Sandler Paula, Richardson Laura. Surveying adolescents enrolled in a regional health plan: Mail & phone followup - What works at what cost? Journal of Adolescent Health 2009;44(2 SUPPL. 1):S37-S37-. [DOI: ] [Google Scholar]
Richards 2010 {published data only}
- Richards J, Wiese C, Katon W, Rockhill C, McCarty C, Grossman D, McCauley E, Richardson LP. Surveying Adolescents Enrolled in a Regional Health Care Delivery Organization: Mail and Phone Follow-up-What Works at What Cost? JOURNAL OF THE AMERICAN BOARD OF FAMILY MEDICINE 2010;23(4):534-541-534-541. [DOI: 10.3122/jabfm.2010.04.100019] [DOI] [PMC free article] [PubMed] [Google Scholar]
Robbins 2018 {published data only}
- Robbins MW, Grimm G, Stecher B, Opfer VD. A Comparison of Strategies for Recruiting Teachers Into Survey Panels. SAGE OPEN 2018;8(3):1. [DOI: 10.1177/2158244018796412] [DOI] [PMC free article] [PubMed] [Google Scholar]
Robin 1973 {published data only}
- Robin DP, Nash HW, Jones SR. An analysis of monetary incentives in mail questionnaire studies. J Business Comm 1973;11:38-42. [Google Scholar]
Robin 1976 {published data only}
- Robin DP, Walters CG. The effect on return rate of messages explaining monetary incentives in mail questionnaire studies. Journal of the Business Community 1976;13(3):49-54. [Google Scholar]
Rocheleau 2012 {published data only}
- Rocheleau Carissa M, Romitti Paul A, Sherlock Stacey Hockett, Sanderson Wayne T, Bell Erin M, Druschel Charlotte. Effect of survey instrument on participation in a follow-up study: a randomization study of a mailed questionnaire versus a computer-assisted telephone interview.. BMC public health 2012;12(100968562):579-579-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Roeher 1963 {published data only}
- Roeher GA. Effective techniques in increasing response to mailed questionnaires. Public Opinion Quarterly 1963;27:299-302. [Google Scholar]
Rudd 1980 {published data only}
- Rudd NM, Maxwell NL. Mail survey response rates: effects of questionnaire topic and length and recipients community. Psychological Reports 1980;46:435-40. [Google Scholar]
Ryan 2018 {published data only}
- Ryan Michael S, Leggio Lisa E, Peltier Christopher B, Chatterjee Archana, Barone Michael A, Arenberg Steven, Byerley Julie S, Belkowitz Julia L, Rabalais Gerard P. Recruitment and retention of community preceptors. Pediatrics 2018;142(3):e20180673-e20180673-. [DOI: ] [DOI] [PubMed] [Google Scholar]
Salomone 1978 {published data only}
- Salomone PR, Miller GC. Increasing the response rates of rehabilitation counselors to mailed questionnaires. Rehabilitation Counseling Bulletin 1978;22:138-41. [Google Scholar]
Senf 1987 {published and unpublished data}
- Senf JH. The option to refuse: a tool in understanding nonresponse in mailed surveys. Evaluation Review 1987;11:775-81. [Google Scholar]
Shackleton 1982 {published data only}
- Shackleton VJ, Wild JM. Effect of incentives and personal contact on response rate to a mailed questionnaire. Psychological Reports 1982;50:365-6. [Google Scholar]
Shah 2016 {published data only}
- Shah Kalpit N, Hofmann Martin R, Schwarzkopf Ran, Pourmand Deeba, Bhatia Nitin N, Rafijah Gregory, Bederman S Samuel. Patient-Reported Outcome Measures: How Do Digital Tablets Stack Up to Paper Forms? A Randomized, Controlled Study.. American journal of orthopedics (Belle Mead, N.J.) 2016;45(7):E451-E457-E451-E457. [PubMed] [Google Scholar]
Shermis 1982 {published data only}
- Shermis MD. Issues in survey data quality: four field experiments. Doctoral Dissertation 1982;University of Michigan ProQuest Dissertations Publishing, 1982. 8304591..
Sheth 1975 {published data only}
- Sheth JN, Roscoe AM. Impact of questionnaire length, follow-up methods, and geographical location on response rate to a mail survey. Journal of Applied Psychology 1975;60(2):252-4. [Google Scholar]
Shin 2015 {published data only}
- Shin N, Simcoe R, Sule H, Massone R, Hall R. Get feedback now: How to best use your residency management software to increase the response rate and quality of conference evaluations. Western Journal of Emergency Medicine 2015;16(Supplement 1):S13-S14-S13-S14. [Google Scholar]
Short 2015 {published data only}
- Short Camille E, Rebar Amanda L, Vandelanotte Corneel. Do personalised e-mail invitations increase the response rates of breast cancer survivors invited to participate in a web-based behaviour change intervention? A quasi-randomised 2-arm controlled trial.. BMC medical research methodology 2015;15(100968545):66-66-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Simcoe 2015 {published data only}
- Simcoe Ross, Hall Ronald, Sule Harsh, Massone Richard, Shin Nara. Get feedback now: Increase your survey response rate by using handheld devices, web-based surveys, and protected time for survey completion. Academic Emergency Medicine 2015;22(5 SUPPL. 1):S217-S218-S217-S218. [DOI: ] [Google Scholar]
Sirken 1960 {published and unpublished data}
- Sirken MG, Pifer JW, Brown ML. Survey procedures for supplementing mortality statistics. American Journal of Public Health 1960;50:1753-64. [DOI] [PMC free article] [PubMed] [Google Scholar]
Smith 1972 {published data only}
- Smith EM, Hewett W. The value of a preliminary letter in postal survey response. Journal of the Marketing Research Society 1972;14(3):145-51. [Google Scholar]
Smith 1977 {published data only}
- Smith K. Signing off in the right colour can boost mail survey response. Industrial Marketing 1977;62:61-2. [Google Scholar]
Smith 1987 {published data only}
- Smith K, Bers T. Improving alumni survey response rates: an experiment and cost-benefit analysis. Research in Higher Education 1987;27(3):218-25. [Google Scholar]
Smith 2019 {published data only}
- Smith MG, Witte M, Rocha S, Basner M. Effectiveness of incentives and follow-up on increasing survey response rates and participation in field studies. BMC MEDICAL RESEARCH METHODOLOGY 2019;19(1):230. [DOI: 10.1186/s12874-019-0868-8] [DOI] [PMC free article] [PubMed] [Google Scholar]
Snyder 1984 {published data only}
- Snyder M, Lapovsky D. Enhancing survey response from initial non-consenters. Journal of Advertising Research 1984;24:17-20. [Google Scholar]
Stenhammar 2011 {published data only}
- Stenhammar Christina, Bokström Pär, Edlund Birgitta, Sarkadi Anna. Using different approaches to conducting postal questionnaires affected response rates and cost-efficiency. JOURNAL OF CLINICAL EPIDEMIOLOGY 2011;64(10):1137-1143-1137-1143. [DOI: ] [DOI] [PubMed] [Google Scholar]
Suhre 1989 {published and unpublished data}
- Surhe C. Schools over the gangway: an experiment on response impoving procedures. Tijdschrift voor Onderwijsresearch 1989;14:172-80. [Google Scholar]
Sullivan 1995 {published data only}
- Sullivan LM, Dukes KA, Harris L, Dittus RS, Greenfield S, Kaplan SH. A comparison of various methods of collecting self-reported health outcomes data among low-income and minority patients. Medical Care 1995;33(4):AS183-94. [PubMed] [Google Scholar]
Sutherland 1996 {published data only}
- Sutherland HJ, Beaton M, Mazer R, Kriukov V, Boyd NF. A randomized trial of the total design method for the postal follow-up of women in a cancer prevention trial. European Journal of Cancer Prevention 1996;5:165-8. [DOI] [PubMed] [Google Scholar]
Tan 1997 {published data only}
- Tan RT, Burke FJT. Response rates to questionnaires mailed to dentists. A review of 77 publications. International Dental Journal 1997;47:349-54. [Google Scholar]
TCTR20190814001 2019 {published data only}
- TCTR20190814001. Comparison of collecting patient-reported outcome measurements between electronic-based and paper-based questionnaire in adults with low back pain: a randomized controlled crossover trial. WHO International Clinical Trials Registry Platform (ICTRP) 2019.
Trice 1985 {published data only}
- Trice AD. Maximizing participation in surveys: hotel ratings VII. Journal of Social Behaviour and Personality 1985;1(1):137-41. [Google Scholar]
Tucker‐Seeley 2009 {published data only}
- Tucker-Seeley Kevon R. The effects of using Likert vs. Visual Analogue Scale response options on the outcome of a web-based survey of 4th through 12th grade students: Data from a randomized experiment.. Dissertation Abstracts International Section A: Humanities and Social Sciences 2009;69(11-A):4305-4305-. [Google Scholar]
Udby 2021 {published data only}
- Udby CL, Riis A, Thomsen JL, Rolving N. Does the use of telephone reminders to increase survey response rates affect outcome estimates? An ancillary analysis of a prospective cohort study of patients with low back pain. BMC Musculoskeletal Disorders 2021;22(1):893. [DOI: 10.1186/s12891-021-04787-4] [DOI] [PMC free article] [PubMed] [Google Scholar]
Van Ryswyk 2016 {published data only}
- Van Ryswyk E M, Middleton P F, Hague W M, Crowther C A. Women's views on postpartum testing for type 2 diabetes after gestational diabetes: Six month follow-up to the DIAMIND randomised controlled trial.. Primary care diabetes 2016;10(2):91-102-91-102. [DOI: ] [DOI] [PubMed] [Google Scholar]
von Allmen 2019 {published data only}
- Allmen RS, Tinner C, Schmidli J, Tevaearai HT, Dick F. Randomized controlled comparison of cross-sectional survey approaches to optimize follow-up completeness in clinical studies. PLOS ONE 2019;14(3):e0213822.. [DOI: 10.1371/journal.pone.0213822] [DOI] [PMC free article] [PubMed] [Google Scholar]
Walker 1977 {published data only}
- Walker BJ, Burdick RK. Advance correspondence and error in mail surveys. Journal of Marketing Research 1977;14:379-82. [Google Scholar]
Wang 2018 {published data only}
- Wang Mengyang. Grid Questions and Data Quality: An Investigation of Grid Placement on Web Surveys Completed across Three Types of Device. ProQuest Dissertations and Theses 2018;(10841678):187-187-.
Ward 1994 {published data only}
- Ward J, Wain G. Increasing response rates of gynaecologists to a survey: a randomised trial of telephone prompts. Australian Journal of Public Health 1994;18(3):332-4. [DOI] [PubMed] [Google Scholar]
Warnock 2022 {published data only}
- Warnock AC, Kaur H, Buckman JR, Hoenemeyer T, Demark-Wahnefried W. A comparison of two mail-based strategies to recruit older cancer survivors into a randomized controlled trial of a lifestyle intervention. JOURNAL OF CANCER SURVIVORSHIP 2022 ;16(5):998-1003. [DOI: 10.1007/s11764-021-01091-x] [DOI] [PMC free article] [PubMed] [Google Scholar]
Watson 1965 {published data only}
- Watson JJ. Improving the response rate in mail research. Journal of Advertising Research 1965;5:48-50. [Google Scholar]
Weiss 1985 {published data only}
- Weiss LI, Friedman D, Shoemaker CL. Prepaid incentives yield higher response rates to mail surveys. Marketing News 1985;19:30-1. [Google Scholar]
Weissenburger 1987 {published data only}
- Weissenburger FE. Effects of prior information on teacher ratings of students with behaviour problems. Doctoral Dissertation 1987.
Weston 2017 {published data only}
- Weston D, Parsons V, Ntani G, Rushton L, Madan I. Mixed contact methods to improve response to a postal questionnaire.. Occupational Medicine 2017;67(4):305-307-305-307. [DOI: ] [DOI] [PubMed] [Google Scholar]
Wildman 1977 {published data only}
- Wildman RC. Effects of anonymity and social setting on survey responses. Public Opinion Quarterly 1977;41:74-9. [Google Scholar]
Willis 2013 {published data only}
- Willis Gordon B, Smith Tenbroeck, Lee Hyunshik J. Do Additional Recontacts to Increase Response Rate Improve Physician Survey Data Quality? Medical care 2013;51(10):945-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
Wood 2017 {published data only}
- Wood J, Cook JA, Hudson J, McDonald A, Bruhn H, Watson AJM. Do higher monetary incentives improve response rates part-way through a randomised control trial? TRIALS 2017;18:P65. [Google Scholar]
Zagumny 1996 {published data only}
- Zagumny MJ, Ramsey R, Upchurch MP. Is anonymity important in AIDS survey research? Psychological Reports 1996;78:270. [DOI] [PubMed] [Google Scholar]
Zheng 2018 {published data only}
- Zheng Guili, Oksuzyan Sona, Hsu Shelly, Cloud Jennifer, Jewell Mirna Ponce, Shah Nirvi, Smith Lisa V, Frye Douglas, Kuo Tony. Self-Reported Interest to Participate in a Health Survey if Different Amounts of Cash or Non-Monetary Incentive Types Were Offered.. Journal of Urban Health 2018;95(6):837-849-837-849. [DOI: 10.1007/s11524-018-0237-7] [DOI] [PMC free article] [PubMed] [Google Scholar]
Ziegenfuss 2012a {published data only}
- Ziegenfuss Jeanette Y, Burmeister Kelly R, Harris Ann, Holubar Stefan D, Beebe Timothy J. Telephone follow-up to a mail survey: when to offer an interview compared to a reminder call.. BMC medical research methodology 2012;12(100968545):32-32-. [DOI: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Zuidgeest 2011 {published data only}
- Zuidgeest Marloes, Hendriks Michelle, Koopman Laura, Spreeuwenberg Peter, Rademakers Jany. A comparison of a postal survey and mixed-mode survey using a questionnaire on patients' experiences with breast care. Journal of medical Internet research 2011;13(3):e68-e68-. [DOI] [PMC free article] [PubMed] [Google Scholar]
Zwisler 2004 {published data only}
- Zwisler LJET, Jarbol LDE, Lous J. Sporgeskemaundersogelser - hvordan opnar jeg en hoj besvarelsesprocent? Ugeskr Laeger 2004;166(7):575-8. [PubMed] [Google Scholar]
References to studies awaiting assessment
Alexander 2008 {published data only}
- Alexander GL, Divine GW, Couper MP, McClure JB, Stopponi MA, Fortman KK, et al. Effect of incentives and mailing features on online health program enrolment. American Journal of Preventive Medicine 2008;34(5):382-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
Balabanis 2007 {published data only}
- Balabanis G, Mitchell VW, Heinonen-Mavrovouniotis S. SMS-based surveys: Strategies to improve participation. International Journal of Advertising 2007;26(3):369-85. [Google Scholar]
Bauman 2016 {published data only}
- Bauman A, Phongsavan P, Cowle A, Banks E, Jorm L, Rogers K, et al. Maximising follow-up participation rates in a large scale 45 and Up Study in Australia. EMERGING THEMES IN EPIDEMIOLOGY 2016;13:6. [DOI] [PMC free article] [PubMed] [Google Scholar]
Bhattarai 2010 {published data only}
- Bhattarai B, Fosgate G T. Increased response proportions for postal questionnaires in Texas veterinarians using incentives. PREVENTIVE VETERINARY MEDICINE 2010;93(1):62-5. [DOI] [PubMed] [Google Scholar]
Bosnjak 2015 {published data only}
- Bosnjak M, Neubarth W, Couper MP, Bandilla W, Kaczmirek L. Prenotification in web-based access panel surveys: the influence of mobile text messaging versus e-mail on response rates and sample composition. Social Science Computer Review 2015;26(2):213-223.
Brusseleers 2019 {published data only}
- Brusseleers M. The ICU Feedback Study: comparing response rate of paper based questionnaires versus electronic questionnaires in patients with a recent intensive care stay. ANZCTR 2019.
Burns 2015 {published data only}
- Burns Frances, Clarke Mike, Maguire Lisa. The NICOLA questionnaire trial (NICOLA-QT): A randomised trial of the effect of timing and mode of delivery on the completion and return of a self-assessment questionnaire. Trials 2015;16(Supplement 2):P107. [Google Scholar]
Damberg 2020 {published data only}
- Damberg C, Bogart A, Orr N, Elliott M, Flora Sheng Y, Zaslavsky A. Simplified notifications improve response rates to patient surveys: Findings from the medicare disenrollment survey experiment. Health Services Research 2020;55(SUPPL 1):108. [Google Scholar]
Davidson 2019 {published data only}
- Davidson T, Cooper D. Trial questionnaire response rates-Is bigger better? Trials 2019;20(Supplement 1):579. [Google Scholar]
Dommeyer 2008 {published data only}
- Dommeyer CJ. The effects of the researcher's physical attractiveness and gender on mail survey response. Psychology & Marketing 2008;25(1):47-70. [Google Scholar]
Dudas 2012 {published data only}
- Dudas D, Hudson D, Kirkland E. Methods used to achieve a high response to cancer prevention study-II (CPS-II) mailings. American Journal of Epidemiology 2012;175(SUPPL. 11):S18. [Google Scholar]
Duncan 2015 {published data only}
- Duncan A, Bonetti D, Clarkson J, Ramsay C. Improving trial questionnaire response rates using behaviour change theory. Trials 2015;16(Supplement 2):P92. [Google Scholar]
Duncan 2017 {published data only}
- Duncan A, Goulao B, Ramsay C, Fee P, McLaren-Neil F, Floate R, et al. When is enough, enough? Replication of behaviour change interventions to minimise attrition of follow up questionnaires. Trials 2017;18(Supplement 1):200.:P428. [Google Scholar]
Edelman 2013a {published data only}
- Edelman Linda S, Guymon Maughan, Yang Rumei, Olson Lenora. Improving Response Rates for Surveys of Rural Community Dwelling Older Adults. Communicating Nursing Research 2013;46:338. [DOI] [PubMed] [Google Scholar]
Epperson 1997 {published data only}
- Epperson WV, Peck RC. Questionnaire response bias as a function of respondent anonymity. Accident Analysis & Prevention 1997;9:249-56. [Google Scholar]
Finkelstein 2016 {published data only}
- Finkelstein Stanley M, Celebrezze Margaret, Cady Rhonda, Lunos Scott, Looman Wendy S. Strategies to Maximize Data Collection Response Rates in a Randomized Control Trial Focused on Children with Medical Complexity. Telemedicine journal and e-health : the official journal of the American Telemedicine Association 2016;22(4):295-301. [DOI] [PMC free article] [PubMed] [Google Scholar]
Goodman 2017 {published data only}
- Goodman K, Hagen S, McClurg D, Sergenson N, Stratton S, Treweek S. Can behaviour change theory increase questionnaire response rates within trials? Trials 2017;18(Supplement 1):200.P439. [Google Scholar]
Griffin 2019 {published data only}
- Griffin Charlotte, Toomey Elaine, Queally Michelle, Hayes Catherine, Kearney Patricia M, Matvienko-Sikar Karen. Influence of providing information to participants about development of trial outcomes on response rates and attitudes to questionnaire completion: Protocol for a study within a trial. HRB open research 2019;2(101754913):2. [DOI] [PMC free article] [PubMed] [Google Scholar]
Ho‐A‐Yun 2007 {published data only}
- Ho-A-Yun J, Crawford F, Newton J, Clarkson J. The effect of advance telephone prompting in a survey of general dental practitioners in Scotland: a randomised controlled trial. Community Dental Health 2007;24(4):233-7. [PubMed] [Google Scholar]
Hopkins 1983 {published data only}
- Hopkins KD, Podolak J. Class-of-mail and the effects of monetary gratuity on the response rates of mailed questionnaires. Journal of Experimental Education 1983;51:169-70. [Google Scholar]
ISRCTN16642368 2016 {published data only}
- ISRCTN16642368. Timing of text message prompts to increase trial participant response to postal questionnaires in UK-FROST. Cochrane Database of Systematic Reviews 2016.
ISRCTN31304930 2014 {published data only}
- ISRCTN31304930. Contacting by telephone prior to dispatching postal questionnaires increases response rates in a senescent and frail patient population. Cochrane Central Register of Controlled Trials 2014.
ISRCTN99859966 2018 {published data only}
- ISRCTN99859966. Postal questionnaire data collection pilot study - APPEAL pilot study. ISRCTN Registry 2018.
Joinson 2007 {published data only}
- Joinson Adam N, Reips Ulf-Dietrich. Personalized salutation, power of sender and response rates to Web-based surveys. Computers in Human Behavior 2007;23(3):1372-83. [Google Scholar]
Kaplowitz 2011 {published data only}
- Kaplowitz, Michael D, Lupi, Frank, Couper, Mick P, et al. The Effect of Invitation Design on Web Survey Response Rates. Social Science Computer Review;30(3):339-349.
Kelly 2010 {published data only}
- Kelly Bridget J, Fraze Taressa K, Hornik Robert C. Response rates to a mailed survey of a representative sample of cancer patients randomly drawn from the Pennsylvania Cancer Registry: a randomized trial of incentive and length effects. BMC medical research methodology 2010;10(100968545):65. [DOI] [PMC free article] [PubMed] [Google Scholar]
Koitsalu 2018 {published data only}
- Koitsalu M, Eklund M, Adolfsson J, Gronberg H, Brandberg Y. Effects of pre-notification, invitation length, questionnaire length and reminder on participation rate: a quasi-randomised controlled trial. BMC MEDICAL RESEARCH METHODOLOGY 2018;18(1):3. [DOI] [PMC free article] [PubMed] [Google Scholar]
Kozak 2020 {published data only}
- Kozak Margaret, Usoz Melissa, Fujimoto Dylann, von Eyben Rie, Kidd Elizabeth. Prospective Randomized Trial of Email and/or Telephone Reminders to Enhance Vaginal Dilator Compliance in Patients Undergoing Brachytherapy for Gynecologic Malignancies. International Journal of Radiation Oncology Biology Physics 2020;108(2 Supplement):E10. [DOI] [PubMed] [Google Scholar]
Langeland 2019 {published data only}
- Langeland JL. The Use of eMail in Establishment Surveys. Dissertation 2019:186.
Maynard 1996 {published data only}
- Maynard ML. Effectiveness of 'begging' as a persuasive tactic for improving response rate on a client / agency mail survey. Psychological Reports 1996;78:204-6. [Google Scholar]
McCrohan 1981 {published data only}
- McCrohan KF, Lowe LS. A cost/benefit approach to postage used on mail questionnaires. Journal of Marketing 1981;45:130-3. [Google Scholar]
Mendoza 2014 {published data only}
- Mendoza CA. Variations in online survey designs. Dissertation 2014:146.
Muñoz‐Leiva 2010 {published data only}
- Muñoz-Leiva Francisco, Sánchez-Fernández Juan, Montoro-Ríos Francisco, Ibáñez-Zapata José Ángel. Improving the response rate and quality in Web-based surveys through the personalization and frequency of reminder mailings. Quality & Quantity 2010;44(5):1037-52. [Google Scholar]
Newton 1998 {published data only}
- Newton K, Stein SM, Lucey C. Influence of mailing strategies on response to questionnaires. Psychiatric Bulletin 1998;22:692-4. [Google Scholar]
O'Keefe 1987 {published data only}
- O'Keefe LB. Selecting cost-effective survey methods: foot-in-door and prepaid monetary incentives. Journal of Business Research 1987;15:365-76. [Google Scholar]
Parast 2018 {published data only}
- Parast Layla, Elliott Marc N, Hambarsoomian Katrin, Teno Joan, Anhang Price Rebecca. Effects of Survey Mode on Consumer Assessment of Healthcare Providers and Systems (CAHPS) Hospice Survey Scores. Journal of the American Geriatrics Society 2018;66(3):546-52. [DOI] [PubMed] [Google Scholar]
Patrick 2021 {published data only}
- Patrick Megan E, Couper Mick P, Parks Michael J, Laetz Virginia, Schulenberg John E. Comparison of a web-push survey research protocol with a mailed paper and pencil protocol in the Monitoring the Future panel survey. Addiction (Abingdon, England) 2021;116(1):191-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
Porter 2007 {published data only}
- Porter SR, Whitcomb ME. Mixed-mode contacts in Web surveys: paper is not necessarily better. Public Opinion Quarterly 2007;71(4):635-48. [Google Scholar]
Price 2004a {published data only}
- Price JH, Yingling F, Walsh E, Murnan J, Dake JA. Tone of postcards in increasing survey response rates. Psychological Reports 2004a;94(2):444-8. [DOI] [PubMed] [Google Scholar]
Price 2004b {published data only}
- Price JH, Yingling F, Walsh E, Murnan J, Dake JA. Tone of postcards in increasing survey response rates. Psychological Reports 2004b;94(2):444-8. [DOI] [PubMed] [Google Scholar]
Price 2004c {published data only}
- Price JH, Yingling F, Walsh E, Murnan J, Dake JA. Tone of postcards in increasing survey response rates. Pyschological Reports 2004c;94(2):444-8. [DOI] [PubMed] [Google Scholar]
Price 2006 {published data only}
- Price JH, Dake JA, Jordan TR, Silvestri KS, Ward BL. Effects of small monetary incentives on return rates of a health survey to adults in rural areas. PSYCHOLOGICAL REPORTS 2006;98(3):849-852-849-852. [DOI: 10.2466/PR0.98.3.849-852] [DOI] [PubMed] [Google Scholar]
Rach 1994 {unpublished data only}
- Rach PJ. An analysis of factors effecting initial response rates to mailed questionnaires. Doctoral Dissertation 1994.
Samel‐Kowalik 2012 {published data only}
- Samel-Kowalik P, Raciborski F, Tomaszewska A, Walkiewicz A, Borowicz J, Lusawa A, et al. Impact of the announcement letter on declaration of asthma, rhinitis and eczema in ECAP study. Allergy: European Journal of Allergy and Clinical Immunology 2012;67(SUPPL. 96):606. [Google Scholar]
Siera 1988 {published data only}
- Siera S and Pettibone TJ. Four methods of following up mailed questionnaires. In: Paper presented at the Annual Meeting of the American Educational Research Association. 1988.
Strickland 1980 {published data only}
- Strickland S. The effect of wording and scale format on student response to educational evaluation questionnaires. Doctoral Dissertation 1980.
Treat 1996 {published data only}
- Treat JB. The effect of questionnaire length on response. Procedings of the Section on Survey, American Statistical Association 1996;1:734-9. [Google Scholar]
Virtanen 2007 {published data only}
- Virtanen Vesa, Sirkiä Timo, Jokiranta Virve. Reducing Nonresponse by SMS Reminders in Mail Surveys. SOCIAL SCIENCE COMPUTER REVIEW 2007;25(3):384-95. [Google Scholar]
Wood 2015 {published data only}
- Wood J, Bruhn H, Cook J A, McDonald A, Norrie J, Watson A J. STRATEGIES TO IMPROVE RESPONSE RATES TO PATIENT REPORTED OUTCOME MEASURES IN A SURGICAL RCT. GUT 2015;64:A161-2. [Google Scholar]
Additional references
Armstrong 1995
- Armstrong BK, White E, Saracci R. Principles of exposure measurement in epidemiology. In: Kelsey JL, Marmot MG, Stolley PD, Vessey MP, editors(s). Monographs in Epidemiology and Biostatistics. First edition. Vol. 21. New York: Oxford University Press Inc., 1995:294-321. [Google Scholar]
Butler 2013
- Butler CC, Simpson SA, Hood K, Cohen D, Pickles T, Spanou C, et al. Training practitioners to deliver opportunistic multiple behaviour change counselling in primary care: a cluster randomised trial.. BMJ 2013;346:f1191. [DOI] [PMC free article] [PubMed] [Google Scholar]
Clarke 1994
- Clarke MJ, Stewart LA. Obtaining data from randomised controlled trials: how much do we need for reliable and informative meta-analyses? BMJ 1994;309:1007-10. [DOI] [PMC free article] [PubMed] [Google Scholar]
Covidence [Computer program]
- Covidence. Melbourne, Australia: Veritas Health Innovation, accessed 7 February 2022. Available at covidence.org.
Edwards 2004
- Edwards P, Roberts I, Sandercock P, Frost C. Follow-up by mail in clinical trials: does questionnaire length matter? Controlled Clinical Trials 2004;25(1):31-52. [DOI] [PubMed] [Google Scholar]
Edwards 2005
- Edwards P, Cooper R, Roberts I, Frost C. Meta-analysis of randomised trials of monetary incentives and response to mailed questionnaires. Journal of Epidemiology and Community Health 2005;59:987-99. [DOI] [PMC free article] [PubMed] [Google Scholar]
Edwards 2005b
- Edwards P, Arango M, Balica L, Cottingham R, El-Sayed H, Farrell, B, et al. Final results of MRC CRASH, a randomised placebo-controlled trial of intravenous corticosteroid in adults with head injury-outcomes at 6 months.. Lancet 2005;365(9475):1957-9. [DOI] [PubMed] [Google Scholar]
Egger 1997
- Egger M, Davey Smith G, Schneider M, Minder C. Bias in meta-analysis detected by a simple graphical test. BMJ 1997;315:629-34. [DOI] [PMC free article] [PubMed] [Google Scholar]
Free 2011
- Free C, Knight R, Robertson S, Whittaker R, Edwards P, Zhou W, et al. Smoking cessation support delivered via mobile phone text messaging (TXT2STOP): a single-blind, randomised trial.. Lancet 2011;378(9785):49-55. [DOI] [PMC free article] [PubMed] [Google Scholar]
Higgins 2003
- Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327(7414):557-60. [DOI: 10.1136/bmj.327.7414.557] [PMID: ] [DOI] [PMC free article] [PubMed] [Google Scholar]
Higgins 2011
- Higgins JP, Altman DG, Gøtzsche PC, Jüni P, Moher D, Oxman AD, et al. The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ 2011 ;343:d5928. [DOI] [PMC free article] [PubMed] [Google Scholar]
Higgins 2022
- Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.3 (updated February 2022). Cochrane, 2022. vailable from www.training.cochrane.org/handbook.
Hook 1992
- Hook EB, Regal RR. The value of capture-recapture methods even for apparently exhaustive surveys. American Journal of Epidemiology 1992;135:1060-7. [DOI] [PubMed] [Google Scholar]
Molm 2010
- Molm LD. The Structure of Reciprocity. Social Psychology Quarterly 2010;73(2):119-131. [Google Scholar]
Nakash 2006
- Nakash RA et al. Maximising response to postal questionnaires – A systematic review of randomised trials in health research. BMC Medical Research Methodology 2006;6:5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Price 2022
- Price RA et al. A Systematic Review of Strategies to Enhance Response Rates and Representativeness of Patient Experience Surveys. Med Care 2022;60:910–918. [DOI] [PMC free article] [PubMed] [Google Scholar]
Review Manager 2020 [Computer program]
- Review Manager 5 (RevMan 5). Version 5.4. Copenhagen: The Cochrane Collaboration, 2020.
Schulz 1995
- Schulz KF, Chalmers I, Hayes RJ, Altman DG. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 1995;273(5):408-12. [DOI] [PubMed] [Google Scholar]
Scott 2006
- Scott P, Edwards P. Personally addressed hand-signed letters increase questionnaire response: a meta-analysis of randomised controlled trials. BMC Health Services Research 2006;6:111. [DOI] [PMC free article] [PubMed] [Google Scholar]
Van Gelder 2010
- Van Gelder MMHJ, Reini W Bretveld RW, Nel Roeleveld N. Web-based Questionnaires: The Future in Epidemiology? Am J Epidemiol 2010;172:1292-1298. [DOI] [PubMed] [Google Scholar]
Yammarino 1991
- Yammarino FJ, Skinner SJ, Childers TL. Understanding mail survey response behaviour: a meta-analysis. Public Opinion Quarterly 1991;55:613-39. [Google Scholar]
References to other published versions of this review
Edwards 2002
- Edwards P, Clarke M, DiGuiseppi C, Pratap S, Wentz R, Kwan I. Increasing response rates to postal questionnaires: systematic review. BMJ 2002;324(7347):1183-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
Edwards 2003
- Edwards PJ, Roberts IG, Clarke M, DiGuiseppi C, Pratap S, Wentz R, et al. Methods to increase response rates to postal questionnaires. Cochrane Database of Systematic Reviews 2003, Issue 4. Art. No: MR000008. [DOI: 10.1002/14651858.MR000008.pub2] [DOI] [PubMed] [Google Scholar]
Edwards 2007
- Edwards PJ, Roberts IG, Clarke MJ, DiGuiseppi C, Wentz R, Kwan I, Cooper R, Felix L, Pratap S. Methods to increase response rates to postal questionnaires. Cochrane Database of Systematic Reviews 2007, Issue 2. Art. No: MR000008. [DOI: 10.1002/14651858.MR000008.pub3] [DOI] [PubMed] [Google Scholar]
Edwards 2009
- Edwards PJ, Roberts I, Clarke MJ, Diguiseppi C, Wentz R, Kwan I, Cooper R, Felix LM, Pratap S. Methods to increase response to postal and electronic questionnaires. Cochrane Database of Systematic Reviews 2009, Issue 3. Art. No: MR000008. [DOI: 10.1002/14651858.MR000008.pub4] [PMID: ] [DOI] [PMC free article] [PubMed] [Google Scholar]