Shouldn't anyone who passes through the training be considered qualified? If training is expensive then you no doubt want to prevent people from starting if you

Shouldn't anyone who passes through the training be considered qualified? If training is expensive then you no doubt want to prevent people from starting if you don't think they're likely to finish, but the metric there should obviously be a bar on absolute student quality, not rank. It should also be measured -- confidence intervals, correlation between input metrics and output performance etc. I bet the marginal student in terms of acceptance is more than likely great doctor material, and I bet it doesn't drop off sharply right past them.