The issue of why women are so underrepresented in the STEM fields—science, technology, engineering, and mathematics—is poorly understood. One thing, however, is certain: They are not going to enter the field if they drop out of school.
And new research finds they are far more likely to do that under a specific set of conditions: when there are few if any other females in their doctoral program.
The results suggest "more female peers create a female-friendly environment that encourages women to persist in doctoral programs," write Ohio State University economists Valerie Bostwick and Bruce Weinberg. Their study is published on the website of the National Bureau of Economic Research.
The researchers examined data on all 2,541 students who enrolled in 33 graduate programs at six public universities in Ohio between 2005 and 2016. They found the average incoming class for such programs was about 38 percent female.
Disciplines who fell below that threshold, including chemical engineering, computer science, and physics programs, were labeled "typically male." In those programs, fewer than five women were part of each incoming class. (On average, the total class size was around 17).
Using a new dataset, the researchers looked at who dropped out of each program, and at what stage. Their key finding: "Women entering cohorts with no female peers are 11.9 percentage points less likely to graduate within six years than their male counterparts."
Those with few female peers did only slightly better. Women doctoral candidates who class had fewer females than average for their field were about 7 percent less likely than their male classmates to graduate in six years.
"But if there were more women than average in the program, that graduation gap goes away," Weinberg said in announcing the findings.
Exploring possible reasons for the higher dropout rate, the researchers found no significant gender difference in the ability to obtain research funding, and only a small difference in grades. The first-term grade point averages of male students were 0.11 percent higher than females, which, the researchers write, explains one-quarter of the graduation gap at most.
This led them to suspect the most important factor is a less easily defined, but highly important variable: the academic climate for women. (It's surely significant that women who dropped out usually did so during their first year.)
"It may be hard to feel like you belong when you don't see other women around you," Bostwick said. "There may be subtle discrimination. We don't know."
The findings suggest universities have much more work to do to make their STEM programs more female-friendly—and the easiest way to do that may be to simply enroll more women.