BCa bootstrap confidence intervals

The existing Stata command bstrap takes a user-defined program and calculates normal approximation, percentile and bias- corrected percentile bootstrap confidence intervals. However, these intervals are not the most accurate available. In this article, we describe a new command, bci, which shares a similar syntax to bstrap, but which additionally calculates the more accurate BCa bootstrap confidence interval, as well as the so-called 'basic' bootstrap confidence interval.