Table 2

Testing post-pre difference of approaches

Approach
Mean (SD)
Pre*
Post*
Post minus Pre
P-value for difference (paired t-test)**

1. Consent for each use
Mean (SD)
0.34 (1.95)
0.14 (2.07)
-0.21 (2.02)
0.315 (df = 95***)
2. Assumed consent
Mean (SD)
0.44 (1.99)
0.18 (2.10)
-0.29 (1.82)
0.122 (df = 96)
3. Broad Consent
Mean (SD)
1.55 (1.64)
1.21 (1.55)
-0.32 (1.54)
0.048 (df = 94)

* 7 Point scale where 3 = strongly like, 0 = neutral, & 3 = strongly dislike

** Bonferroni correction: Alpha = 0.017 (0.05/3)

*** df: Degree of freedom;

Willison et al. BMC Medical Ethics 2008 9:18   doi:10.1186/1472-6939-9-18