Table 3.
Monetary and non-monetary incentives
| Monetary incentives | Intervention | OR | 95%CI |
|---|---|---|---|
| Deehan et al., 1997 [11] |
£10 vs no incentive |
3.14 |
2.37, 4.15 |
| |
£5 vs no incentive |
2.22 |
1.66, 2.98 |
| |
£10 charity donation vs no incentive |
1.20 |
0.85, 1.69 |
| |
£5 charity donation vs no incentive |
1.12 |
0.79, 1.57 |
| |
Pooled (Deehan, 1997) |
1.87 |
1.48, 2.36 |
| Everett et al., 1997 [28] |
$1bill vs no incentive |
1.86 |
1.34, 2.57 |
| |
Pooled |
1.87 |
1.55, 2.26 |
|
Nonmonetary incentives |
|
|
|
| Baron et al., 2001 [29] |
Lottery to win weekend trip vs No incentive |
1.31 |
1.02, 1.70 |
| McLaren and Shelley, 2000 [30] |
Awareness of prize vs no awareness of prize |
1.17 |
0.84, 1.61 |
| Pit et al., 2013 [25] |
Pen vs no incentive |
1.85 |
0.91, 3.77 |
| Robertson et al., 2005 [31] |
AU$2 Lottery vs no incentive |
1.78 |
1.23, 2.60 |
| |
Pooled |
1.39 |
1.15, 1.69 |
|
Large vs small incentives |
|
|
|
| Asch et al., 1998 [26] |
US$5 vs US$2 |
1.83 |
1.43, 2.35 |
| Deehan et al., 1997 [11] |
£10 cash vs £5 cash |
1.41 |
1.06,1.87 |
| |
£10 charity donation vs $5 |
1.08 |
0.73,1.58 |
| Thomson et al., 2004 [32] |
Lottery to win a large prize (6 bottles of champagne) vs six chances to win one bottle |
1.47 |
1.05, 2.08 |
| |
Pooled |
1.47 |
1.19,1.81 |
|
Prepaid vs promised incentives |
|
|
|
| James et al., 2011 [27] | US$25 prepaid vs US$25 promised | 2.88 | 1.70, 4.89 |