The rise of the middle author: Investigating collaboration and division of labor in biomedical research using partial alphabetical authorship

Contemporary biomedical research is performed by increasingly large teams. Consequently,an increasingly large number of individuals are being listed as authors in thebylines, which complicates the proper attribution of credit and responsibility to individualauthors. Typically, more importance is given to the first and last authors, while it is assumedthat the others (the middle authors) have made smaller contributions. However, this may notproperly reflect the actual division of labor because some authors other than the first andlast may have made major contributions. In practice, research teams may differentiate themain contributors from the rest by using partial alphabetical authorship (i.e., by listing middleauthors alphabetically, while maintaining a contribution-based order for more substantialcontributions). In this paper, we use partial alphabetical authorship to divide the authors ofall biomedical articles in the Web of Science published over the 1980±2015 period in threegroups: primary authors, middle authors, and supervisory authors. We operationalize theconcept of middle author as those who are listed in alphabetical order in the middle of anauthors' list. Primary and supervisory authors are those listed before and after the alphabeticalsequence, respectively. [...