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 |