, Volume 95, Issue 3, pp 895–909 | Cite as

A scientometrics law about co-authors and their ranking: the co-author core

  • M. AusloosEmail author


Rather than “measuring” a scientist impact through the number of citations which his/her published work can have generated, isn’t it more appropriate to consider his/her value through his/her scientific network performance illustrated by his/her co-author role, thus focussing on his/her joint publications, and their impact through citations? Whence, on one hand, this paper very briefly examines bibliometric laws, like the h-index and subsequent debate about co-authorship effects, but on the other hand, proposes a measure of collaborative work through a new index. Based on data about the publication output of a specific research group, a new bibliometric law is found. Let a co-author C have written J (joint) publications with one or several colleagues. Rank all the co-authors of that individual according to their number of joint publications, giving a rank r to each co-author, starting with r = 1 for the most prolific. It is empirically found that a very simple relationship holds between the number of joint publications J by coauthors and their rank of importance, i.e., J ∝ 1/r. Thereafter, in the same spirit as for the Hirsch core, one can define a “co-author core”, and introduce indices operating on an author. It is emphasized that the new index has a quite different (philosophical) perspective that the h-index. In the present case, one focusses on “relevant” persons rather than on “relevant” publications. Although the numerical discussion is based on one “main author” case, and two “control” cases, there is little doubt that the law can be verified in many other situations. Therefore, variants and generalizations could be later produced in order to quantify co-author roles, in a temporary or long lasting stable team(s), and lead to criteria about funding, career measurements or even induce career strategies.


Citation Count Scientific Network Joint Publication Publication List Prolific Author 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The author gratefully acknowledges stimulating and challenging discussions with many wonderful colleagues at several meetings of the COST Action MP-0801, ‘Physics of Competition and Conflict’. In particular, thanks to O. Yordanov for organising the May 2012 meeting “Evaluating Science: Modern Scientometric Methods”, in Sofia, and challenging the author to present new results. All colleagues mentioned in the text have frankly commented upon the manuscript and enhanced its content. Reviewer comments have, no doubt, much improved the present version of the ms.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2013

Authors and Affiliations

  1. 1.LiègeBelgium
  2. 2.GRAPES@SUPRATECS, ULGLiègeBelgium

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