Understanding the odds ratio and the relative risk.

Both the odds ratio and the relative risk compare the relative likelihood of an event occurring between two groups. The relative risk is easier to interpret and is consistent with general intuition. Some designs, however, allow only for the calculation of the odds ration. Covariate adjustment is easier for an odds ratio. Finally, the odds ratio avoids ambiguity by being invariant to lthe labeling of the outcome measure. The Table summarizes the advantages and disadvantages of the odds ratio and relative risk. Whe reading research that summarizes data using odds ratios, or relative risks, be aware of the limitations of booth of these measures.