Why collaboration with men is dominating in science? Gender homophily among 25,000 academic scientists

We examined the male-female collaboration practices of all internationally visible Polish university professors (N = 25,463) based on their Scopus-indexed publications from 2009–2018 (158,743 journal articles). We merged a national registry of 99,935 scientists with the Scopus publication database, using probabilistic and deterministic record linkage. Our database (“The Polish Science Observatory”) included all professors with at least a doctoral degree employed in 85 research-involved universities. We determined an “individual publication portfolio” for every professor. The gender homophily principle (publishing predominantly with scientists of the same sex) was found to apply to male scientists - but not to females. The majority of male scientists collaborate solely with males; most female scientists, in contrast, do not collaborate with females at all. Gender homophily in research-intensive institutions proved stronger for males than for females. Finally, we used a multi-dimensional fractional logit regression model to estimate the impact of gender and other individual-level and institutional-level independent variables on gender homophily in research collaboration.