[skuxxlife]

The general consensus is it is at least somewhat due to socialization and gender norms for women, which strongly encourage agreeability, friendliness, and deference to authority (at least in the western world), which are not advantageous in negotiation. When men are aggressive, they're seen as assertive and commanding, but when women exhibit the same behaviors they're often seen as pushy, shrill, or difficult. Anecdotally, women do research salaries, they do talk to each other (though often their networks are not as deep and their comparison point may be other underpaid women), but even talented, confident women can struggle to balance advocating for themselves aggressively while avoiding being seen negatively for doing so. It's hard to fight against an environment which says you should act a certain way to be accepted whether you buy into it or not.

So how do we make things more fair? IMO, pay transparency, narrow well-defined pay bands, explicit job duties and expectations, mentorship for women entering the field, and generally reducing the effect of good negotiation skills in roles where negotiation skills aren't critical to the job.