Change-in-Ratio Estimators for Populations with More Than Two Subclasses

Change-in-ratio methods have been developed to estimate the size of populations with 2 or 3 population subclasses. Most of these methods require the often unreasonable assumption of equal sampling probabilities for individuals in all subclasses. This paper presents new models which provide explicit estimates of population size for populations with 3 or more subclasses. The new models are based on the weaker assumption that sampling probabilities are equal for only 2 of the subclasses and that the ratios of the sampling probabilities remain constant over time. Extensions of these models which require an additional sample but further relax the assumption of equal sampling probabilities are discussed. Likelihood ratio