Effect Size Calculator

David B. Wilson, PhD, George Mason University
Version date: 2023.11.27

Odds Ratio/Risk Ratio from Proportions

Proportion
with Event

Sample
Size

Treatment

Control

Odds ratio

Risk ratio

OR =

RR =

95% C.I. =

95% C.I. =

ORlogged =

RRlogged =

vORlogged =

vRRlogged =

seORlogged =

seRRlogged =

Notes: This method computes the odds and risk ratios from the proportion of successes (or failures) on a binary outcome variable. The “Proportion with Event” is simply the proportion of individuals (or other units of analysis) within each group with the outcome of interest.