Sample size calculations in studies of test accuracy

Abstract

Methods for determining sample size for studies of the accuracy of diagnostic tests are reviewed. Several\raccuracy indices are considered, including sensitivity and speci®city, the full and partial area under the\rreceiver operating characteristic curve, the sensitivity at a ®xed false positive rate, and the likelihood\rratio. Sample size formulae are presented for studies evaluating a single test and studies comparing the\raccuracy of tests. Four real examples illustrate the concepts involved in sample size determination. Lastly,\rvarious study design issues are discussed, such as sampling methods, choices in format for the test results,\rand the issue of replicated readings.