title: Determination of significant relative risks and optimal sampling procedures in prospective and retrospective comparative studies of various sizes.
abstract: Methods are given for determining the relative risks which it is possible to demonstrate as statistically significant with given probability in prospective and retrospective studies of a particular size. Also considered is the ratio of the sample sizes in the two groups being compared which will provide the most precise estimate of relative risk for a given total sample size.
mesh_terms: D001699:Biometry; D004812:Epidemiologic Methods; D011446:Prospective Studies; D012189:Retrospective Studies; D012306:Risk; D012494:Sampling Studies