from Paul Graham | by Paul Graham

A selection process will be unbiased only if (a) the later performance of those selected is measured and (b) the selectors are judged according to this.

(Notice incidentally that venture funding has both of these, and American college admissions has neither.)

Since this is Twitter, I must remind everyone that "x only if y" doesn't mean that if y is true, then x will be, but rather that if y is false, then x will be. E.g. I'm not saying "measured means unbiased," but that "not measured means biased."