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Document set current to 30 July 2026
Defined term · Statistics and inference

Risk ratio

The ratio of event probabilities in two arms. More directly interpretable than an odds ratio for common outcomes.

Document identifier
CEI-GT-072
Series
Defined term
Version
1.0
Published
30 Jul 2026
Last reviewed
30 Jul 2026
Certainty
Not rated

§1Risk ratio

§1.1Also known as

Relative risk

§1.2Category

Statistics and inference — Terms describing how effects are estimated and how uncertainty is expressed.

§1.3Related terms

  • Odds ratio — The ratio of the odds of an event in two arms. Approximates the risk ratio only when the event is uncommon, and departs from it materially for common outcomes.
  • Absolute risk difference — The difference in event probability between arms. Depends on baseline risk and is the measure from which a number needed to treat is derived.
Compound Evidence Institute · CEI-GT-072 · https://compoundevidence.com/glossary/risk-ratio/ · retrieved 30 July 2026
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