In reply to Tobi.

That shouldn't happen in practice. It might be an indication that (1) Your bootstrap samples are incorrect, (2) You are bootstrapping a statistic (such as a median or maximum) that is not appropriate for bootstrapping, or (3) You need to increase the number of resamples, B.

You are correct that this can theoretically happen. If all the bootstrap statistics are less than the observed statistic, I would use (B-1)/B as an estimate of PropLess. So, in the bootBC module, you could insert the statement

if propLess=1 then propLess = (B-1)/B;

before calling the QUANTILE function.