Sample Size: X-Sectional, Cohort, & Randomized Clinical Trials | |||
Two-sided significance level(1-alpha): | 95 | ||
Power(1-beta, % chance of detecting): | 80 | ||
Ratio of sample size, Unexposed/Exposed: | 1 | ||
Percent of Unexposed with Outcome: | 15 | ||
Percent of Exposed with Outcome: | 5.5 | ||
Odds Ratio: | 0.32 | ||
Risk/Prevalence Ratio: | 0.36 | ||
Risk/Prevalence difference: | −9.8 | ||
Kelsey | Fleiss | Fleiss with CC | |
Sample Size-Exposed | 151 | 150 | 170 |
Sample Size-Nonexposed | 151 | 150 | 170 |
Total sample size: | 302 | 300 | 340 |
References | |||
Kelsey et al., Methods in Observational Epidemiology 2nd Edition, Tables 12-15 | |||
Fleiss, Statistical Methods for Rates and Proportions, Formulas 3.18 & 3.19 | |||
CC = Continuity Correction | |||
Results are rounded up to the nearest integer |