Zippin's procedure is one of the most accurate methods used to estimate total populations from removal trapping data. However, explicit algebraic solutions of the maximum likelihood equations do not exist. Hitherto they have been obtained from graphs known as Zippin charts. In this paper a Newton-Raphson procedure is used to obtain numerical solutions to the equations. Comparisons with the classical method show some differences in the parameters, particularly in the estimation of the standard error.
Populations estimates; Estimation technics