Maximum Likelihood Applied to a Capture-Recapture Model

Maximum likelihood is applied to a capture-recapture model in order to estimate the population size, n. The likelihoods to which this model gives rise can be highly skew. It is shown that the use of n-3 gives an approximately normal likelihood. This results in a function that has an approximately standard normal distribution and is linear in n-3. Thence complete sets of approximate confidence intervals can be obtained merely by the use of a pocket calculator.