Gender inequalities among authors who contributed equally

Abstract

We analyzed 2898 scientific papers published between 1995 and 2017 in which two or more authors shared the first author position. For papers in which the first and second authors made equal contributions, mixed-gender combinations were most frequent, followed by male-male and then female-female author combinations. For mixed-gender combinations, more male authors were in the first position, although the disparity decreased over time. For papers in which three or more authors made equal contributions, there were more male authors than female authors in the first position and more all-male than all-female author combinations. The gender inequalities observed among authors who made equal contributions are not consistent with random or alphabetical ordering of authors. These results raise concerns about female authors not receiving proper credit for publications and suggest a need for journals to request clarity on the method used to decide author order among those who contributed equally.

Keywords: co-authorship; gender bias; gender equity; human biology; infectious disease; medicine; microbiology; none; publication; scientific credit.

Figure 1.. Proportion of various gender combinations among joint first authors in scientific papers published between 1995 and 2017.

We studied papers in which two or more authors shared the first author position: ‘fm’, ‘ff’, ‘mf’ and ‘mm’ represent papers in which two authors shared the first author position, with the actual order of the authors being female-male, female-female, male-female and male-male. For papers in which more than two authors shared the first author position, ‘all f’ means that all these authors were female, ‘all m’ means they were all male, and ‘f+’ or 'm+' means that the first author listed in a mixed-gender combination was female or male respectively. The plot shows that the proportion of combinations in which a male author is listed first (various shades of blue) is decreasing over time.

Figure 1—figure supplement 1.. Distribution of papers analyzed per year in this study.

Figure 2.. Gender bias in the first author position over time.

Temporal trend in gender bias among two equally contributing authors of different gender: the y-axis is log (p/(1 p)) where p is the probability of bias; the x-axis is publication year. In the absence of bias, log (p/(1 p)) would be zero.

Figure 3.. Percentage of papers with two or more authors contributing equally as a function of time.

Points denote the percentage of papers with where more than two authors claimed equal contribution. Trendline R² value as 0.4857.

Figure 4.. Gender bias in first authorship by year and geography.

Predicted probabilities of male first authorship by year for three geographical regions (USA: blue; Europe: green; Other: red) among papers with two equally contributing authors of different gender (N = 972).