ESTIMATING PREVALENCE FROM THE RESULTS OF A SCREENING TEST

Abstract
This paper deals with some basic properties of screening tests. Such tests, purport to separate people with disease from people without. Minimal criteria for such a process to be a test are discussed. Various ways of judging the goodness of a test are examined. A common use of tests Is to estimate prevalence of disease; frequency of positive tests Is shown to be a bad estimate, and the necessary adjustments are given.