Bootstrap estimate of the Fried index. The long red dash indicates the estimate yield by the observed data, whereas the long black dash shows the bootstrap mean and 95% percentile interval in the blue line. (A) and (B) are intervention part 1 and 2 estimation of the Fried index from 1,000 bootstraps in the distributions of sterile-to-wild male ratios in the control and release areas, respectively. The density corresponds to the percentage of the simulations for a given value.