Keywords: Capture-recapture, computer simulation

Examined here is a capture-recapture analysis designed to provide estimates of the size of the New York State ?methadone-competing? treatment population. Unlike the traditional capture-recapture approaches that compromise assumptions regarding closed populations and homogeneous probability of capture, the proposed model incorporates dynamical aspects of the population into the estimate. The analysis is based on data from New York State?s Office of Alcoholism and Substance Abuse Service Client Data System (CDS) which contains a rich source of methadone treatment data. A model and simulation of this population is presented for the period 1977 through 1997. This research was supported by grant 270-96-0019 from the Center for Substance Abuse Treatment.