Moodie 2011.

Methods	Country: Scotland Setting: Greater Glasgow Date: May ‐ June 2010 Design: Counterbalanced repeated measures (within‐participants) experiment with 2 weeks using standardised pack and 2 weeks using their own branded packs. Participants completed questionnaires twice a week resulting in 4 questionnaires per brand type (referred to as questionnaire 1, 2, etc)
Participants	48 young adult smokers aged 18 ‐ 35 years. Door‐knock method from 14 postcode sectors using random location quota sampling; conducted by market recruiters. Average age = 27 years; 50% men (n = 24)
Interventions	IV: Branded vs standardised packs Branded = Own regular pack brand, e.g. the brand they normally smoke. UK cigarette packs contained 1 of 2 text health warnings on the front (‘Smoking kills’ or ‘Smoking seriously harms you and others around you’) and 1 of 14 ‘pictorial’ warnings on the reverse panel, although 3 are in fact text warnings as they do not display a picture, photo, pictogram or symbol Standardised (plain) = The plain packs were otherwise identical, with a fictitious brand name Kerrods, to prevent copyright breach, and all relevant legal markings and a barcode. All Kerrods packs had the same warning on the pack front TEXT only ('Smoking kills') and one ‘pictorial’ warning on the reverse panel showing a set of healthy and diseased lungs, to save costs Average size HW for both types of packs: 30% on front and 40% on back
Outcomes	[Secondary behavioural]: smoke less around others, forego smoking, stubbing out cigarettes early, keeping pack out of sight or covering pack, measured via yes/no responses [Secondary non‐behavioural]: thinking about quitting, motivation to quit, feelings about smoking (enjoyable, satisfying), pack perceptions(stylish, fashionable, cheap, cool, attractive, quality, appealing), health warnings (noticeable, believable, seriousness, highlighting the health risks of smoking). All measured on 5‐point scales Composite scores were derived for categories of responses (such as pack perceptions, response to warnings), by summing the individual items and then rescaling to a 5‐point scale Analysis summary: Analysis focused on comparing ratings between branded and standardised packs. For each time point, paired t‐tests were used to produce mean scores for the standardised packs relative to mean scores for their own packs. Given the ordinal nature of the 5‐point scales, the Wilcoxon signed rank test, a non‐parametric procedure suited to paired data, was used to test for significant differences between the ratings of standardised packs versus the ratings of the participant’s own packs at each measure. Data on occurrence of avoidant behaviours are binary (yes/no), and the McNemar test was used to test for differences in response between participants’ measures at each time point on the standardised pack and the respective measure on their own pack
Funding source	"Cancer Research UK; UK Centre for Tobacco Control Studies fund two of the authors (GH and AF)"
Conflicts of interest	"None"
Notes	All potential participants were informed that the study was concerned with smokers' experiences of, and opinions about, tobacco packaging
Risk of bias
Bias	Authors' judgement	Support for judgement
Selective reporting (reporting bias)	Low risk	Comment: First study of its kind with appropriate outcomes
Sampling Method	Low risk	Quote: “Young adult smokers (n=140) were recruited from 14 randomly selected postcode sectors in Greater Glasgow, using random location quota sampling. The 14 postcode sectors were randomly selected, stratified by deprivation category score (a measure of multiple deprivation), to ensure coverage of a range of socio‐economic backgrounds. Within each selected postcode sector, 10 participants were recruited, using the door knock method, according to quota controls on age, gender and social grade.” Comment: Sampling used random location quota sampling techniques
Measurement of independent variable	Low risk	Quote: “ [from a pilot] Smokers did not question the authenticity of the Kerrods packs or highlight any problems transferring their cigarettes into these packs, which took only a minute or so. All smokers reported using the packs for the 2 weeks, although one smoker reported not using the pack on a night out after he ran out of cigarettes.” Comment: Kerrods and their own packs were not identical apart from the branding, e.g. the brand name differed, but they were clearly distinguishable from branded packs
Measurement of dependent variable	Low risk	Quote: “A pre‐pilot naturalistic study was then conducted with six smokers, in March 2010, who were provided with 14 plain packs (without cigarettes inside) and asked to transfer cigarettes from their packs into the plain packs each day for a 2‐week period. They were also asked to complete identical questionnaires every second day for these 2 weeks. Questionnaires were developed by the research team, primarily from smokers’ reactions to plain packs within the focus groups, and covered five areas: pack perceptions, pack feelings, feelings about smoking, health warnings (measured on five‐point scales) and behavioural change/avoidant behaviour (measured via yes/no responses). The items on behaviour change and avoidant behaviour were adapted from the International Tobacco Control project. Two focus groups were subsequently employed to explore participants’ experience of using the plain packs, completing and comprehension of the questionnaires, and any aspects of the study protocol that could be improved. The two focus groups thought that the questionnaire was comprehensible but completing it every second day was cumbersome” "The questionnaire was informed by piloting and using previously used measures. The frequency of completion was reduced to twice a week based on the above feedback in the pilot study”
Control for confounding	High risk	One group only, and possible confounders not controlled for
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: “From the 140 participants recruited, 34 (25%) were noncompleters, who failed to participate at all, 58 (41%) were partial completers (who participated but did not return all the questionnaires or report using the correct pack) and 48 (34%) were completers, who completed the full study as intended. Noncompleters, with a mean age of 23 years (SD=4.7), were younger than both completers (mean age= 27 years, SD=5.5) and partial completers (mean age= 28 years, SD=5.5). There was no marked difference in participation, however, by amount smoked, motivation to quit or attempts to quit. The analysis focuses only on the 48 completers.” Comment: 34% of those who were recruited completed the study
Statistical methods	Low risk	Comment: Appropriate