  There are different ways in which the authors of a scientific publication can
determine the order in which their names are listed. Sometimes author names are
simply listed alphabetically. In other cases, authorship order is determined
based on the contribution authors have made to a publication.
Contribution-based authorship can facilitate proper credit assignment, for
instance by giving most credits to the first author. In the case of
alphabetical authorship, nothing can be inferred about the relative
contribution made by the different authors of a publication. In this paper, we
present an empirical analysis of the use of alphabetical authorship in
scientific publishing. Our analysis covers all fields of science. We find that
the use of alphabetical authorship is declining over time. In 2011, the authors
of less than 4% of all publications intentionally chose to list their names
alphabetically. The use of alphabetical authorship is most common in
mathematics, economics (including finance), and high energy physics. Also, the
use of alphabetical authorship is relatively more common in the case of
publications with either a small or a large number of authors.
