[mining]

> Indeed, if women were systematically underpaid despite equivalent performance, I find it hard to believe they wouldn't be hired by the boatload. This might be explained by (1) a lack of women relative to men in the developer workforce and (2) a systematic bias in competence.

Or (3) because a huge proportion of perceived performance is subjective. I can't find a study right now, but e.g. http://fortune.com/2014/08/26/performance-review-gender-bias... make a decent argument towards women receiving qualitatively different performance feedback to men.