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 2 | |||

Fleiss, Statistical Methods for Rates and Proportions, Formulas 3.18 & 3.19 | |||

CC = Continuity Correction | |||

Results are rounded up to the nearest integer |