By focusing on the process in situations where employees bargain over their salaries with their employers as individuals, as opposed to receiving a set rate for the job, the research finds really striking differences between men and women.

Unique data on individual wage bargaining was collected from university graduates in two surveys in 1999 and 2000. Information was collected on the applicant's wage bid (the wage asked for if employment were to occur) and on the offered wage (or starting salary) at the time when employment began.

The results?

- When women bargain with a prospective employer over salary, they submit lower wage bids and are offered lower wages than men.

- Like men, women use self-promoting or competitive bargaining strategies (such as over-bidding) but they self-promote at lower levels, in other words they may over-bid but by less than men.

- Employers reward self-promotion but the larger the self-promotion, the larger is the gender gap in bargaining success, so more assertive bargaining tactics work better for men than for women.

- Women therefore lack the incentives to self-promote, which helps to explain gender disparities.

Thanks to nordicmodel for drawing my attention to this research.