Although women make up the majority of students in many fields of science, they're underrepresented in terms of things like faculty hiring, invitations to conferences, grant awards, and nominations for professional awards. Another professional activity important for career advancement is participating in the peer review process, but, since that's generally anonymous, it's harder to track.

A new comment paper published in Nature shows that women are disproportionately underutilized as reviewers. This bias likely results from authors and editors who suggest female reviewers less often.

The authors of this paper analyzed a large dataset from the American Geophysical Union (AGU), which publishes 20 journals that collectively release nearly 6,000 papers per year. The AGU is the largest society publisher of earth science and space science. The data included more than 106,000 authors; the demographics of this group were similar to the science and technology demographics of the United States. For example, from 2013 to 2015, approximately 28 percent of AGU members were women, which is close to the ratio of female scientists and engineers who were employed during those same years.

The authors matched the gender and age of more than 7,000 distinct first authors who submitted over 22,000 manuscripts between 2012 and 2015. Overall, they found that women participated less as authors and that female first authors submitted approximately 0.79 fewer papers per person than male first authors.

But the acceptance rate for female first-authored papers was slightly higher than the male acceptance rate: 61 percent compared to 57 percent, a finding that was statistically significant for all scientists under 60 years old. The authors suggest that this higher acceptance rate for female authors is likely due to more targeted submissions from women, including better matching of topics to journals. They base this on studies that show that people put more effort into a task when they are expecting greater obstacles, though they note that more research on this phenomenon is needed before strong conclusions can be drawn.

The researchers next considered the gender ratio of the peer reviewers, which should be similar to the gender ratio of published authors. However, women were only 20 percent of all reviewers in 2012 to 2015, whereas they were 27 percent of published first authors and 28 percent of AGU members. This proportionally lower percentage of female peer reviewers was seen across most ages and was statistically significant in older age cohorts, so it cannot be explained by age-related gender differences in career choices and seniority.

The researchers explore two possible reasons for women’s lower participation rates: fewer women may be nominated to review manuscripts or that women decline invitations to review manuscripts more often than men do. They found the former to be a bigger influence. Female first authors suggested female reviewers 21 percent of the time, while male first authors only suggested female reviewers 15 percent of the time. Similarly, female journal editors recommended female reviewers 22 percent of the time, whereas male editors only recommended female reviewers 17 percent of the time.

But both factors seemed to be at play. The researchers found that women of almost all ages declined invitations for peer reviewing at a slightly higher rate than men in the same age group, a difference that was statistically significant for all ages except for people in their 60s and 80s.

Reviewing new manuscripts is an important part of professional development in research fields. If women are being asked to review fewer manuscripts, then they may be being kept from important professional opportunities. Encouraging authors and editors to select more women for the peer review process is a good first step toward evening out this imbalance, and moving forward, all organizations should examine their internal protocols to ensure that they’re not participating in biased practices.