Alphabetical author order and co-author contributions in mathematics

In this study we investigate the relative contributions of co-authors to publications in mathematics. Mathematics is an interesting case for such research because it is one of only a few scientific disciplines in which alphabetical order of names of co-authors on publications is still the prevailing convention rather than contribution-based order. The study is based on unique data of publicly available author-provided quantitative contribution statements for co-authored papers from applications for habilitation degrees in Poland. This data allows us to investigate if alphabetical name order goes hand in hand with equally large contributions of co-authors or hides differences in contribution sizes. We find that the empirical contributions by co-authors are usually close to the equal contributions suggested by alphabetical order but in a substantial proportion of observations the equality assumption would be misleading about actual contributions. This has implications for bibliometric methodology. In mathematics, equal fractional counting of author contributions is close to the contributions declared by the authors themselves. We further find that authors who are habilitation applicants claim slightly more credit, ceteris paribus, than their non-applicant co-authors.