Estimating the size of subpopulations of heroin users: applications of log-linear models to capture/recapture sampling.

This article reviews two of the major methodologies applied to estimation of the number of heroin abusers: survey research methods and the capture/recapture technique. The main focus of the paper is to show the flexibility of the capture/recapture approach in handling not only the dependence of samples of heroin users but also the nonhomogeneity of sampling probabilities, allowing estimation in populations which are mixtures of qualitatively different heroin user types. Models with these features are illustrated using both simulated and real heroin abuse data.