Thank you for the reference to the bibliography. However, it does not really contain many papers (except perhaps for Antelman and Lawrence) that support the claim that OA increases citations by 50% to 250%--and it omits the Anderson paper, which did not show an effect.
The claim seems to come mainly from the paper of Brody et al (Citation Impact of Open Access Articles vs. Articles available only through subscription ("Toll-Access"),
http://citebase.eprints.org/isi_study/). I think these authors have generalized their findings far beyond what the data can support. They are convincing when they stick to the core Physics/Mathematics papers in the ArXiv database, but not when they try to apply their method to other disciplines.
Their method is to compare citations for papers in ArXiv vs. those that are not. Outside of the core physicians and mathematics literature, however, ArXiv contains very few papers from disciplines like medicine or social sciences. For most fields, Brody finds that the number of papers that are 0A are less than 1%--sometimes much less than 1%. For these papers, which are likely to be highly specialized and relatively obscure, self-archiving probably does have a large effect. One can not conclude, however, that the same effect would occur for a widely-read, widely cited journal, like Pediatrics or Diabetes Care. I suspect--and the Anderson paper may hint at this--that the more widely read the journal, the less the citation advantage for OA.
What we need to study other disciplines are archives like ArXiv. Perhaps there are others in certain fields that could be mined for research.
Peter Banks
Acting Vice President for Publications/Publisher
American Diabetes Association
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703/299-2033
FAX 703/683-2890
Email: pbanks_at_diabetes.org
>>> peters_at_earlham.edu 09/28/05 6:22 PM >>>
At 07:37 PM 9/27/2005, Peter Banks wrote:
>[...]
>Although Peter Suber recently claimed (in a letter to the Washington
>Times) that "Study after study has shown that free online access
>increases the impact of research literature, as measured by citations, 50
>percent to 250 percent," I am not sure what "study after study" refers
>to, though is clearly is a reference to Harnad's work.
>
>Dr. Harnad has provided one other refererence
><http://www.crsc.uqam.ca/lab/chawki/graphes/EtudeImpact.htm>, so perhaps
>"study after study" means literally that: two studies. Or maybe there are
>more, but I can't find references.
I was referring to the many studies collected by Steve Hitchcock in his
excellent bibliography:
The effect of open access and downloads ('hits') on citation impact: a
bibliography of studies
http://opcit.eprints.org/oacitation-biblio.html
Peter
----------
Peter Suber
Open Access Project Director, Public Knowledge
Research Professor of Philosophy, Earlham College
Author, SPARC Open Access Newsletter
Editor, Open Access News blog
http://www.earlham.edu/~peters/
peter.suber_at_earlham.edu
American Diabetes Association
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Visit us at
http://diabetes.org
Or Call 1-800-DIABETES (800-342-2383)
Received on Thu Sep 29 2005 - 21:23:40 BST