[Posted with permission]
---------- Forwarded message ----------
Date: Tue, 10 Oct 2006 14:05:49 -0400
From: Michael Kurtz <kurtz -- cfa.harvard.edu>
To: Stevan Harnad <harnad -- ecs.soton.ac.uk>
Dear Stevan and list,
Recently Stevan has copied me on two sets of correspondence concerning
the OA citation advantage; I thought I would just briefly respond to both.
Besides our IPM article:
http://adsabs.harvard.edu/abs/2005IPM....41.1395K we have recently
published two short papers, both with graphs you might find interesting.
The preprint will appear in Learned Publishing
http://adsabs.harvard.edu/abs/2006cs........9126H E-prints and Journal
Articles in Astronomy: a Productive Co-existence
and this is in the J. Electronic Publishing
http://adsabs.harvard.edu/abs/2006JEPub...9....2H Effect of E-printing
on Citation Rates in Astronomy and Physics
There is a point I would like to emphasize from these papers. Figure 2
of the Learned Publishing paper shows that the number of ADS users who
read the preprint version once the paper has been released drops to near
zero. This shows that essentially every astronomer has subscriptions to
the main journals, as ADS treats both the arXiv links and the links to
the journals equally; also it shows that astronomers prefer the journals.
Figure 5 of the J Electronic Publishing paper also shows that there is
no effect of cost on the OA reads (and thus by extension citation)
differential. Note in the plot that there is no change in slope for the
obsolescence function of the reads (either of preprinted or
non-preprinted) at 36 months. At 36 months the 3 year moving wall
allows the papers to be accessed by everyone, this shows clearly that
there is no cost effect portion of the OA differential in astronomy.
This confirms the conclusion of my IPM article.
Now three comments:
Citations are probably the least sensitive measure to see the effects of
OA. This is because one must be able to read the core journals in order
to write a paper which will be published by them. It is really not
possible for a person who has not been regularly reading journal
articles on, say, nuclear physics, to suddenly be able to write one, and
cite the OA articles which enabled that writing. It takes some time for
a body of authors who did not previously have access to form and write
acceptable papers.
Any statistical analysis of the causal/bias distinction must take into
account the actual distribution of citations among articles. This is
why I made the monte carlo analysis in the IPM paper. As a quick
example for papers published in the Astrophysical Journal in 2003: The
most cited 10% have 39% of all citations, and are 96% in the arXiv; the
lowest cited 10% have 0.7% of all citations and are 29% in the arXiv.
Showing the causal hypothesis is true will be very difficult under these
conditions.
Perhaps the journal which is most sensitive to cancellations due to OA
archiving is Nuclear Physics B; it is 100% in arXiv, and is very
expensive. I have several times seen librarians say that they would
like to cancel it. One effect of OA on Nuclear Physics B is that its
impact factor (as we measure it, I assume ISI gets the same thing) has
gone up, just as we show in the J E Pub paper for Physical Review D.
Whether Nuclear Physics B has been cancelled more than Nuclear Physics A
or Physics Letters B must be well known at Elsevier.
Best wishes to all,
Michael
--
Dr. Michael J. Kurtz
Harvard-Smithsonian Center for Astrophysics
60 Garden Street
Cambridge, MA 02138
USA
VOICE: +1-617-495-7434
FAX: +1-617-495-7467
E-MAIL: kurtz -- cfa.harvard.edu
WWW: http://cfa-www.harvard.edu/~kurtz
Received on Sat Oct 14 2006 - 14:27:32 BST