Sample Size Calculator

All methods

Effect measures — RR, OR, HR

Use when the study is powered on a ratio measure of association rather than on a difference: relative risk in a cohort, odds ratio in a case-control study, hazard ratio in a time-to-event study.

3 methods

Effect measures — RR, OR, HR

  1. 11 Cohort study — risk ratio
  2. 12 Case-control study — odds ratio
  3. 13 Hazard ratio — Schoenfeld