Open Access News

Stevan Harnad, Craig et al.'s Review of Studies on the OA Citation Advantage, Open Access Archivangelism, May 26, 2007.

Summary:  The thrust of Craig et al.'s critical review (which was proposed by the Publishing Research Consortium and conducted by the staff of three publishers) is that despite the fact that virtually all studies comparing the citation counts for OA and non-OA articles keep finding the OA citation counts to be higher, it has not been proved beyond a reasonable doubt that the relationship is causal.

I agree: It is merely highly probable, not proved beyond a reasonable doubt. And I also agree that not one of the studies done so far is without some methodological flaw that could be corrected. But it is also highly probable that the results of the methodologically flawless versions of all those studies will be much the same as the results of the current studies. That's what happens when you have a robust major effect, detected by virtually every study, and only ad hoc methodological cavils and special pleading to rebut each of them with. Here is a common sense overview:

(1) Research quality is a necessary, but not a sufficient condition for citation impact: The research must also be accessible to be cited.

(2) Research accessibility is a necessary but not a sufficient condition for citation impact: The research must also be of sufficient quality to be cited.

(3) The OA impact effect is the finding that an article's citation counts are positively correlated with the probability that that article has been made OA: The more an article's citations, the more likely that that article has been made OA.

(4) That correlation has at least three (compatible) causal interpretations:
(4a) OA articles are more likely to be cited.
(4b) More-cited articles are more likely to be made OA.
(4c) A third factor makes it more likely that certain articles will be both more cited and made OA.

(5) Each of these causal interpretations is probably correct, and hence a contributor to the OA impact effect:
(5a) The better the article, the more likely it is to be cited, hence the more citations it gains if it is made more accessible (4a). (OA Article Quality Advantage, QA)
(5b) The better the article, the more likely it is to be made OA (4b). (OA Article Quality Bias, QB)
(5c) 10% of articles (and authors) receive 90% of citations. The authors of the better articles know they are better, and hence are more likely both to be cited and to make their articles OA, so as to maximize their visibility, accessibility and citations (4c). (OA Author QB and QA)

(6) In addition to QB and QA, there is an OA Early Access effect (EA): providing access earlier increases citations.

(7) The OA citation studies have not yet isolated and estimated the relative sizes of each of these (and other) contributing components. (OA also gives a Download Advantage (DA), and downloads are correlated with later citations; OA articles also have a Competitive Advantage (CA), but CA will vanish -- along with QB -- when all articles are OA).

(8) But the handwriting is on the wall as to the benefits of making articles OA, for those with eyes to see, and no conflicting interests to blind them.

Given all of this, here is a challenge for Craig et al: Instead of striving, like OJ Simpson's Dream Team, only to find flaws in the positive evidence for the OA impact differential, which is equally compatible with either interpretation (OA causes higher citations or higher citations cause OA) why don't Craig et al. do a simple study of their own? Since it is known that (in science) the top 10% of articles published receive 90% of the total citations made, why not test whether and to what extent the top 10% of articles published is over-represented among the c. 15% of articles that are being spontaneously made OA by their authors today? It is, after all, a logical possibility that all or most of the top 10% are already among the 15% that are being made OA: I think it's improbable; but it may repay Craig et al's effort to check whether it is so. 

For if it did turn out that all or most of the top-cited 10% of articles are already among the c.15% of articles that are already being made OA, then reaching 100% OA would be far less urgent and important than I have been arguing, and OA mandates would likewise be less important. I for one would no longer find it important enough to archivangelize if I knew it was just for the bottom 90% of articles, the top 10% of articles having already been self-archived, spontaneously and sensibly, by their top 10% authors without having to be mandated. But it is Craig et al. who think this is closer to the truth, not me. So let them go out and demonstrate it.