A unified approach for estimating population size in capture-recapture studies with arbitrary removals

A unified approach is suggested to estimate the population size for a close d population in discrete time. Individuals can be removed after capture at any time during the experiment. The usual recapture and removal experiments are shown to be particular cases of the general formulation. The capture p robability is assumed to have a logistic function that depends on individua l covariates and can be time dependent. The unified approach involves a two -step procedure. A conditional likelihood function is used to estimate the covariates' coefficients and a Horvitz-Thompson type estimator to estimate the population size. The asymptotic and small-sample properties of the resu lting estimators are investigated. A real example is given.