Effects of heterogeneity on population size estimator. A) Coefficient of variation of population size estimator as estimated from simulated data as a function of population heterogeneity for two different population sizes. The registration rate parameter p was randomly varied from unit to unit according to a normal distribution. The population heterogeneity was taken as the standard deviation of this normal distribution (x-axis). B) Bias of population size estimator as estimated from simulated data for different levels of population heterogeneity. The inset shows a histogram illustrating the distribution of rate parameter p corresponding to a heterogeneity of 0.25 (the ps have been scaled by 1000 to improve readability). All simulations in this figure were run with a sample size of 50% of the total population size.