Is it reasonable to limit scientific coauthorship? There is no inflation of co-authors in Social Sciences and Education in Spain

This paper analyzes the evolution of coauthorship in Spain in the social sciences between 2000 and 2013. The goal is to explore to which extent limitations on the number of coauthors established by Spanish national evaluation agencies are justified. The analysis of 11681 papers authored by researchers affiliated to Spanish institutions in 20 subject categories of the social sciences reveals that there is no inflation in the number of authors, team size is similar to that found in foreign papers and the number of authors is dependent on international and institutional collaboration. With the exception of Anthropology and Special Education, in no area the average of authors by paper is higher than four. However, papers with a higher number of authors receive more citations. Overall, our results suggest that there is no justification on limiting the number of coauthors in publications, acknowledging that their inclusion in the criteria employed by Spanish evaluation agencies is to prevent honorary authors. Such limitation endangers institutional and international collaboration, and consequently, high impact research.