Whether it's math aptitude or an aptitude in some other tangentially related field, I think the idea is that men in general tend to have more variance in their

Whether it's math aptitude or an aptitude in some other tangentially related field, I think the idea is that men in general tend to have more variance in their distribution, though the mean ends up being about the same. "Small differences in the distributions of men and women don't allow you to predict much about any individual trait of a randomly selected individual. But when you limit yourself to the far tails of probability distributions, they do. " So, he's saying that by being more selective for a field that men have greater variance in, you're more likely to find more men at the far tails.