Date Published: April 26, 2019
Publisher: Public Library of Science
Author(s): Luke Holman, Claire Morandin, Sergi Lozano.
Evidence suggests that women in academia are hindered by conscious and unconscious biases, and often feel excluded from formal and informal opportunities for research collaboration. In addition to ensuring fairness and helping to redress gender imbalance in the academic workforce, increasing women’s access to collaboration could help scientific progress by drawing on more of the available human capital. Here, we test whether researchers tend to collaborate with same-gendered colleagues, using more stringent methods and a larger dataset than in past work. Our results reaffirm that researchers co-publish with colleagues of the same gender more often than expected by chance, and show that this ‘gender homophily’ is slightly stronger today than it was 10 years ago. Contrary to our expectations, we found no evidence that homophily is driven mostly by senior academics, and no evidence that homophily is stronger in fields where women are in the minority. Interestingly, journals with a high impact factor for their discipline tended to have comparatively low homophily, as predicted if mixed-gender teams produce better research. We discuss some potential causes of gender homophily in science.
Women are severely underrepresented in many branches of science, technology, engineering, mathematics, and medicine (STEMM), and face additional challenges and inequities relative to men [1–5]. On average, women occupy more junior positions [6, 7] with lower salaries [8, 9], receive less grant money [10, 11], are promoted more slowly [12–15], and are allocated fewer resources  and less research funding [17–19]. Experimental evidence suggests that bias against women plays a major role in generating these differences [20, 21].
We found evidence that researchers work with same-gendered coauthors more often than expected under the null model, even after implementing stringent controls for Wahlund effects of the kind illustrated in Fig 1. Our study therefore reaffirms earlier studies’ conclusions [49–57, 62] using stricter methodology, and generalises their results across the life sciences. Relatively few journals had α′ values below zero, and almost no journals showed statistically significant gender heterophily after controlling for multiple testing. The excess of same-gender coauthorships was quite large: many journals had α′ > 0.1, indicating that the gender ratio of men’s and women’s coauthors differs by >10% in absolute terms. In relative terms, our findings are even more striking: for example, if men have 20% female coauthors and women have 30% (i.e. α′ = 0.1 in a field with a typical gender ratio ), then women publish with women 50% more often than men do.