Women aren't born wanting to earn less money

The myth of women's "preferences"

Women in unionized workplaces like MBTA face less of a gender pay gap than their nonunionized counterparts. (Photo by David L. Ryan/The Boston Globe via Getty Images)

Do women choose to earn less money? There’s a persistent effort to naturalize the gender wage gap; that is, to show that women earn less than men not because of discrimination or bad policy design but simply because they choose to.

A 2022 paper titled “Why Do Women Earn Less than Men? Evidence from Bus and Train Operators” began with the premise that, in the United States, the gender pay gap is around 18%. The economists zoomed in on the Massachusetts Bay Transportation Authority, or MBTA, which runs transit in the Boston metropolitan area, to illuminate the drivers of the gender pay gap.

Here they found a much lower gap: around 11%. Since these are the same workplaces (so career choice does not matter), all workers have similar minimal training (so there are no education decisions), they do the same work, and all workers are unionized (so a lot of discretionary pay decisions cannot legally happen), why is there still a wage gap?

The main innovation of the paper, like most contemporary economics research, is in the data: MBTA granted the authors confidential administrative data used by their HR department, merging time card data (that is, when someone starts and stops working) with particular worker characteristics (age, gender, prior experience, marital status, etc.). So the paper is more an accomplishment in quilting than in economic theory.

That way, considering MBTA has very few discretionary decisions on worker pay and promotions, the authors can isolate a very small source of variability: scheduled and unscheduled overtime and paid and unpaid time off (family leave, known as FMLA for the Family and Medical Leave Act). The authors found that the 11% gap in earnings between male and female bus and train operators comes from the fact that women take less unscheduled overtime and take more unpaid time off.

Regardless of seniority, men take about twice as much overtime as women when it is scheduled on short notice, and women take about twice as much unpaid family leave. Given that the number of hours worked is one of the very few decisions workers have over their earnings at MBTA, this explains basically all of the gap away.

The authors present four possible explanations:

The first is the value of time: Women just like spending less time at work than men.

The second is schedule predictability: Women don’t like time off more than men, but can’t take time off at short notice.

The third is schedule conventionality (preferring a 9-to-5 more strongly), which is just the value of time with extra steps.

The fourth is a stronger response by men than women to undesirable schedules, which, again, is just the value of time.

So, really, there are two explanations: Women just like spending time at work less or that women can’t take short-notice overtime.

The biggest gap in short-notice overtime is between unmarried women and men with children: Men take overtime 40% of the time, and women 34%. However, this happens because the gap in pre-planned overtime is very small (around 7%), while the gap in short-notice overtime is around 45%, and closer to 60% for unmarried men and women with dependents.

At MBTA, men recover the pay they lose to family leave by working extra hours, but women don’t, and that’s most pronounced for unmarried mothers. That’s sometimes taken as evidence that women just value time off more.

But when MBTA tightened its leave and overtime rules to stop people from using leave to skip the least desirable shifts, the pay gap fell to about 6%. That’s probably the most you could honestly blame on free individual choice — roughly half of MBTA’s gap, which is itself about half of the U.S. average. And, of course, people do not make choices in a vacuum.

The right-wing Mises Institute argued that the wage gap is mainly about women’s choices. In another Mises paper about the gender wage gap, the author argued that “female preferences for caregiving and stability align with evolutionary roles in child-rearing, implying that gender roles are deeply rooted in biology rather than social constructs.” It attributed much of the wage gap to choices “shaped by hormonal and biological influences.”

An opinion column on FoxNews.com argued that “women are doing just fine” and “by most measures, it’s our boys and men who are struggling.” The author claimed that “to the extent that the gap exists, it can be largely attributed to deliberate and meaningful choices made by women in the workforce that prioritize home and family over career.”

This is a common refrain among the right: That our choices can be structured by our institutional and cultural environment — which conservatives usually understand well — suddenly reads like liberal gobbledygook when applied to the question of what shapes women’s preferences.