Odds ratios are not conditional risk ratios

Risk ratios and odds ratios--what are they?

A risk ratio (sometimes called relative risk, both abbreviated to RR) and an odds ratio (OR) are ways of expressing a comparison between two proportions. For example, in this paper, there are two randomised groups in the trial, women in the lateral position and women in the supported sitting position in the passive second stage of labour. The authors wanted to compare the proportions of instrum...

The relative merits of risk ratios and odds ratios.

When a study outcome is rare in all strata used for an analysis, the odds ratio estimate of causal effects will approximate the risk ratio; therefore, odds ratios from most case-control studies can be interpreted as risk ratios. However, if a study outcome is common, the odds ratio will be further from 1 than the risk ratio. There is debate regarding the merits of risk ratios compared with odds...

Response to letter to the editor by A. Huitfeldt Re: Odds ratios deconstructed: a new way to understand and explain odds ratios as conditional risk ratios.

OBJECTIVES The aim of this analysis was to provide an alternative derivation of the odds ratio (OR) to provide an intuitive meaning, freeing it from any mention of odds, which may make it a more useful concept for clinicians to use when describing treatment effect. STUDY DESIGN AND SETTING By examining the four possible combinations of treatment/control and corresponding outcomes, we consider...

Relative Risk and Odds Ratios Examples

Mischievous Odds Ratios