The lesbian pay gap

Eric Crampton quotes Big Think:

The wage premium paid to lesbian workers is a bit of a mystery. Sure, lesbian women are better-educated on average, are more likely to be white, live predominantly in cities, have fewer children, and are significantly more likely to be a professional. But even when you control for these differences, the wage premium is still on the order of 6%. …

Eric offers some theories on why this might be:

First, and most importantly, maternity risk. If an employer expects a lesbian employee to be less likely to take maternity leave, and if maternity leave imposes costs on an employer, then the employer will be more likely to hire and to promote the lesbian over the straight woman. What evidence do we have? Petit’s field experimentshowing that maternity risk is responsible for a fair bit of women’s lower average salaries.

How could this be tested in the data presumably available in the original study? Test whether the wage gap between lesbian and straight women is larger for younger women than for post-menopausal women. That will confound with age cohort effects, but there may be a way around it: use state insurance mandates on assisted reproduction, or state policies with respect to same-sex adoption. If some states require that insurers cover fertility treatments as part of an employer’s insurance package and others don’t, or if some states make it easier for lesbians to adopt kids, then we’d expect the wage gap between lesbians and straights to be smallest in those states that make it easiest for lesbians to have kids.

Second, testosterone and negotiation strategies. Women, on average, are less aggressive in wage negotiations. If testosterone correlates with aggressiveness in salary negotiations, and some evidence suggests higher than average testosterone levels among lesbians as compared to heterosexual women (though that evidence iscontested), then we’ve another candidate explanation.

I’d put money on the maternity risk variable. I’d only put money on the negotiations one at decent odds.

I go the other way to Eric. I think the theory of more assertiveness in salary negotiations is most likely to explain the gap.