Table 1

Number required in each group to detect differences with 80% power at the 5% significance level given that group prevalences are p1% and p2%

Prevalence (p2%):
Prevalence (p1%):10203040506070
5 4407433191285
10 200603017117
20 29680372012
30 360924021
40 3929640
50 39292
60 360