Bootstrap resampling technique was applied to compute the variance of mixtures of truncated count data since the direct computation via the information matrix was usually difficult. For each nonparametric bootstrap, frequencies n n1, 2,,nm were sampled from a multinomial distribution with size parameter n and categorical probability parameters ni n ; then Nˆ was constructed using the BIC-selected mixture model. Suppose that there were B samples of size n each, population size estimates Nˆ1*,,Nˆ B* were available. These resampled data were used to compute variances and confidence intervals as asymptotic normal intervals.