DETERMINATION OF SIGNIFICANT RELATIVE RISKS AND OPTIMAL SAMPLING PROCEDURES IN PROSPECTIVE AND RETROSPECTIVE COMPARATIVE STUDIES OF VARIOUS SIZES

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.