[wenc]

Again, multivariate thinking is important. GPA alone doesn't predict everything, but it is one predictor in a complicated function and it may have varying sensitivities in different ranges as well as have interacting terms with other variables.

One needs to factor in all the other predictors, as you alluded to in your story.

[mrkstu]

The question is how do you reliably gather a rich dataset that encompasses those variables. It is an un-solved problem vs shortcuts like GPA and prestige of their attended institutions.