The odds of a given outcome (= p/q, where p is the proportion with the outcome and q is the proportion without the outcome) for participants with a particular characteristic, divided by the odds of that outcome for participants without the characteristic (or with one unit less of the characteristic). Helpful outlines of how the statistic can be applied in epidemiological studies are available as are warnings about its misuses. Also available are calculators for the ratio and associated confidence intervals.
See Attributable fraction, Case-comparison design, Cumulative incidence (CI), Epidemiological studies, Epidemiology, Hazard ratio, Influence efficacy, Likelihood ratio (LR), Precision, Rate ratio