Table 2.
Extracted quantitative data from the 35 included papers.
| Author | Number recruited |
Recruitment length (months)a |
Impressions (millions) |
Cost per ad click (US $)b | Conversion rate (%), n numbers included where available |
Eligibility (%), n numbers included where available |
Cost per participant (US $)b |
| Adam LM (2016) [15] | 45 | 0.8 | 0.04 | 0.21b | NRc | 56 (n=45) | 15.12b |
| Admon L (2016) [29] | 1178 | 1.0 | 0.36 | 0.58 | 13.2 (n=1592) | 74 (n=1178) | 14.63 |
| Akard TF (2015) [17] | 106 | 2.0 | 3.90 | 1.08 | 3.0 | 61 (n=106) | 17 |
| Arcia, A (2014) [18] | 344 | 4.0 | 10.50 | 0.63 | 6.0 | 50 | 11.11 |
| Batterham PJ (2014) [28] stage 1 |
610 | 0.1 | NR | NR | 3.0 | NR | 9.82b |
| Batterham PJ (2014) [28] stage 2 |
1283 | 0.1 | NR | NR | 3.0 | NR | 1.51b |
| Bauermeister JA (2012) [30] | 22 | NR | NR | NR | NR | NR | NR |
| Bull S (2013) [31] | 1578 | 36.0d | NR | NR | NR | NR | NR |
| Carlini B (2015) [19] | 285 | 4.0 | NR | NR | NR | NR | 8.92 |
| Carter-Harris L (2016) [9] | 331 | 0.6 | 0.06 | 0.45 | 29.5 | NR | 1.51 |
| Child RJH (2014) [20] | 78 | 0.1 | NR | NR | NR | NR | NR |
| Chu JL (2013) [21] | 88 | 9.0 | 17.50 | 0.39b | 5.0 (n=180) | 49 | 15.35b |
| Close S (2013) [22] | 39 | 0.2 | 2.50 | 0.61 | 18.0 | NR | 19.44 |
| Crosier BS (2016) [32] | 264 | 1.0 | 0.01 | 0.20 | NR | NR | 8.14 |
| Fenner Y (2012) [33] | 278 | 4.0 | 36.10 | 0.48b | 4.0 | NR | 14.50b |
| Frandsen TL (2014) [6] | 138 | 19.0 | 14.50 | 0.68b | NR | NR | 30.48b |
| Frandsen M (2016) [10] | 92 | 13.5 | NR | NR | NR | 61 | 74.64b |
| Harris ML (2015) [34] | NR | 8.0 | NR | 0.51b | 2.0 | 93 (n=3795) | 8.55b |
| Jones R (2015) [35] | 230 | 1.0 | NR | 0.36 | 3.0 | 39 | 37.74 |
| Kappa JM (2013) [36] | 0 | 0.3 | 0.90 | 0.98 | 3.0 | 78 (n=280) | NR |
| Miyagi E (2014) [37] | 126 | 9.0 | 5.70 | NR | NR | 95 | NR |
| Moreno MA (2017) [14] | 8 | NR | NR | NR | NR | NR | 40.99 |
| Morgan AJ (2015) [16] | 35 | 11.0 | 2.00 | 0.45b | NR | NR | 14.32b |
| Musiat P (2016) [38] | 26 | 3.0 | 0.50 | 1.74b,d | 0.1 | 90 | 76.15b |
| Nelson EJ (2014) [24] | 1003 | 2.0 | NR | NR | 48.0d(n=1003) | 91 | 1.36 |
| Parkinson S (2013) [39] | 100 | 0.2 | 1.30 | NR | 15.0 | 83 | NR |
| Pedersen ER (2014) [25] | 1023 | 1.0 | 3.30 | 0.38 | 5.0 | 45 | 7.05 |
| Ramo DE (2014) [40] | 1548 | 13.0 | 28.70 | 0.45 | 1.0 | NR | 4.28 |
| Ramo DE (2012) [41] | 230 | 2.0 | 3.20 | 0.34 | 9.0 | 51 | 8.80 |
| Raviotta JM (2016) [11] | 428 | 6.0 | 21.00 | 1.24 | NR | NR | 110.00d |
| Remschmidt C (2014) [42] | 1161 | 2.0 | 62.90 | NR | 9.0 | NR | NR |
| Schumacher KR (2014) [26] | 394 | 12.0 | NR | NR | NR | 100 (n=394) | NR |
| Schwinn T (2017) [43] | 797 | 4.2 | 187.00d | 0.6 | 2.8 | 43 (n=1873) | 51.70 |
| Staffileno BA (2016) [13] | 23 | 18.0 | NR | 0.73 | NR | 17 | NR |
| Subasinghe AK (2016) [12] | 919 | 13.0 | 55.40 | 0.67b | NR | NR | 17.29b |
| Yuan P (2014) [27] | 1404 | 4.0 | NR | NR | NR | NR | 3.56 |
aCalculated as a percentage of a 31-day month.
bAUD converted to USD with 0.72 and CD to USD with 0.75 exchange rates where appropriate.
cNR: not reported; not reported if data unavailable.
dOutliers of over 3 standard deviations excluded from statistical calculation.