Systematics in Citation Statistics: Implications for the "OA Advantage"

From: Michael Kurtz <>
Date: Fri, 14 Dec 2007 10:46:59 -0500

A recent paper by Joerg P. Dietrich "The Importance of Being First:
Position Dependent Citation Rates on arXiv:astro-ph" shows that systematic increases in
citation rates on the order of the 2 to 1 "OA advantage" can be obtained
by other, systematic means, such as author bias, as pointed out by
myself (, Moed
( and others. Note that OA plays no
role in the Dietrich paper, all the articles are from arXiv.

The Importance of Being First: Position Dependent Citation Rates on
J.P. Dietrich


We study the dependence of citation counts of e-prints published on the
arXiv:astro-ph server on their position in the daily astro-ph listing.
Using the SPIRES literature database we reconstruct the astro-ph
listings from July 2002 to December 2005 and determine citation counts
for e-prints from their ADS entry. We use Zipf plots to analyze the
citation distributions for each astro-ph position. We find that e-prints
appearing at or near the top of the astro-ph mailings receive
significantly more citations than those further down the list. This
difference is significant at the 7 sigma level and on average amounts to
two times more citations for papers at the top than those further down
the listing. We propose three possible non-exclusive explanations for
this positional citation effect and try to test them. We conclude that
self-promotion by authors plays a role in the observed effect but cannot
exclude that increased visibility at the top of the daily listings
contributes to higher citation counts as well. We can rule out that the
positional dependence of citations is caused by the coincidence of the
submission deadline with the working hours of a geographically
constrained set of intrinsically higher cited authors. We discuss
several ways of mitigating the observed effect, including splitting
astro-ph into several subject classes, randomizing the order of
e-prints, and a novel approach to sorting entries by relevance to
individual readers.

Dr. Michael J. Kurtz
Harvard-Smithsonian Center for Astrophysics
60 Garden Street
Cambridge, MA 02138
VOICE: +1-617-495-7434
FAX: +1-617-495-7467
Received on Fri Dec 14 2007 - 20:13:46 GMT

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