How do women and men differ in research collaborations based on authorship positions? The Spanish case

Fernanda Morillo¹Manuel Escabias-Machuca²Zaida Chinchilla-Rodríguez^3*

• ¹Instituto de Filosofía (IFS), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
• ²Department of Statistic and Operations Research, University of Granada, Granada, Spain
• ³Institute of Public Goods and Policies, Spanish National Research Council (CSIC), Madrid, Madrid, Spain

This study examines gender disparities in authorship and collaboration within the Spanish scientific workforce, focusing on international and industry co-authored publications. Drawing on a comprehensive dataset of over 165,000 publications and more than 170,000 identified authors affiliated with Spanish institutions, the analysis explores how gender interacts with authorship position, research field, career stage, and team size. The results reveal a consistent underrepresentation of women in both types of collaboration, particularly in key authorship roles (first, last, and corresponding author). While women are more active at early career stages, their visibility in leadership roles tends to diminish over time, especially as the number of co-authors increases. Fieldspecific patterns show that even in highly feminized disciplines, such as Biomedical & Health Sciences, women are less likely to appear in prominent authorship positions. These findings raise important concerns about current research assessment practices that rely heavily on byline position as a proxy for contribution or leadership. The study contributes to ongoing discussions on responsible metrics and proposes policy recommendations to promote more equitable evaluation systems that reflect the collaborative and diverse nature of research careers