• Discriminant analysis (DA) is a family of statistical methods in which the primary purpose is to predict into which of several discrete groups (eg, diagnostic categories) an individual subject should be classed. This might be called the classification or forecasting function. A second use of DA examines how well the derived discrimination equation fits the data from which it is derived. This is called the evaluation function of the analysis. Examples of familiar clinical situations show how DA might be relevant to health care decisions, especially classification decisions.