I've written a number of posts on the gender gap in economics, but also in STEM (science, technology, engineering, and maths) (see here for example). In some of those posts on economics, the research I've been discussing has highlighted the potential effect of role models on the gender gap.

If role models matter, then you'd expect the gender of professors to matter. The problem with evaluating that empirically is that students often have some choice over who their professors are, particularly in large classes early in their studies, where there may be many sections to choose from, or the same papers may be taught in multiple semesters. This 2010 article by Scott Carrell, Marianne Page (both University of California at Davis), and James West (US Air Force Academy), published in the *Quarterly Journal of Economics* (ungated earlier version here), is able to overcome that problem.

Carrell et al. use data from the US Air Force Academy, where:

...students are randomly assigned to professors for a wide variety of mandatory standardized courses.

That means that there will be no problems of selection bias, where students choose their own professors. In addition:

...course grades are not determined by an individual student’s professor. Instead, all faculty members teaching the same course use an identical syllabus and give the same exams during a common testing period.

That means that there is also no bias arising from differential grading between different professors. Carrell et al. have data from 9015 students from the USAFA graduating classes of 2001 through 2008. They focus their attention on mathematics, physics, chemistry, engineering, history, and English classes, and look at how the gender of the professor in each introductory class affects students' grades, the likelihood of taking further classes in the discipline, and the likelihood of graduating with a STEM degree. They find that:

...professor gender has only a limited impact on male students, it has a powerful effect on female students’ performance in math and science classes, their likelihood of taking future math and science courses, and their likelihood of graduating with a STEM degree. The estimates are robust to the inclusion of controls for students’ initial ability, and they are substantially largest for students with high SAT math scores.

Specifically, for female students:

...having a female professor reduces the gender gap in course grades by approximately two-thirds.

That is quite substantial, given that after controlling for mathematical ability, female students on average perform 15 percent of a standard deviation worse than male students, in STEM courses. However, it is notable that they also find that:

...at the top of the distribution... having a female professor completely closes the gender gap...

The effect on taking additional STEM classes and graduating with a STEM degree is also concentrated amongst female students with greater mathematical ability, and eliminates the gender gap in those measures as well.

However, the same effect of professor gender are not apparent in the humanities:

In contrast, the gender of professors teaching humanities courses has, at best, a limited impact on students’ outcomes.

All of this suggests that, if we want to narrow the gender gap in STEM, particularly amongst the most able female students, universities would need to employ more female teaching staff. However, Carrell et al. bury a very important caveat in a footnote on the last page of their article:

Note that the impact of female professors may reflect the high quality of faculty at the USAFA, and that substituting lower-quality female professors for high-quality male professors is not a policy that would be recommended by the authors.

Universities need to fully understand the trade-offs before they jump into a policy response. And also, USAFA is a pretty unique environment, so it would be good to know if similar results are obtained in other contexts. However, this research adds to the increasing evidence that the impact of professor gender on the performance and academic decision-making of female students.

Read more:

- STEM-readiness and the gender gap in STEM at university
- Comparative advantage and the gender gap in STEM
- More on comparative advantage and the gender gap in STEM