[lexcorvus]

I didn't say there are no valid examples of bias, just that many people assume unequal outcomes must result from unequal opportunity, ignoring the possibility of real group differences. Surely you know many real-life Alans who see bias every time a particular Group X is underrepresented in Field Y. Moreover, the values of X aren't random; you'll almost never hear complaints of bias regarding, say, trash haulers, or NFL cornerbacks. (But NFL quarterbacks—ah, plenty of bias there!)

[mannykannot]

Speculative explanations - i.e. assumptions - are not uncommonly offered in support of the proposition that there is no underlying bias. Nl provides a rare example of the assumptions being systematically investigated.