Open Access Archivangelism

(1) Yes, we cited the Davis et al study. That study does not show that the OA citation advantage is a result of self-selection bias. It simply shows (as many other studies have noted) that no OA advantage at all (whether randomized or self-selected) is detectable only a year after publication, especially in a small sample. It's since been over two years and we're still waiting to hear whether Davis et al's randomized sample still has no OA advantage while a self-selected control sample from the same journals and year does. That would be the way to show what the OA advantage is a self-selection bias. Otherwise it's just the sound of one hand clapping.

Harnad, S (2008) Davis et al's 1-year Study of Self-Selection Bias: No Self-Archiving Control, No OA Effect, No Conclusion. Open Access Archivangelism. July 31 2008.

(2) No, we did not look only at self-archiving in institutional repositories. Our matched-control sample of self-selected self-archived articles came from institutional repositories, central repositories, and authors' websites. (All of that is "Green OA.") It was only the mandated sample that was exclusively from institutional repositories. (Someone else may wish to replicate our study using funder-mandated self-archiving in central repositories. The results are likely to be much the same, but the design and analysis would be rather more complicated.)

(4) Yes, we systematically excluded articles in Gold OA journals from our sample, not because we do not believe that they generate the OA advantage too, but because it is impossible to do matched-control comparisons between OA and non-OA articles in the same journal issue with Gold OA journals, since all their articles are OA. (It would for much the same reason be difficult to do this comparison in a field where 100% of the articles were OA, even if we were interested in unrefereed preprints; but we were not: we were interested in open access to refereed journal articles.)

(5) As to the 60% mandated self-archiving rates: The institutions we studied had mandated OA in 2003-2004. Our test time-span was 2002-2006. At least two of those institutions (Southampton ECS and CERN) and probably the other two also (Minho and QUT) have deposit rates of close to 100% by now. (We have since extended the analyses to 2009 and found exactly the same result.)

(6) "What is wrong if [OA] rates are 15%"? We leave that to the reader as an exercise. That, after all, is what OA is all about. But surveys have shown -- and outcome studies have confirmed -- that although most researchers do not self-archive spontaneously, 95% report that they would self-archive if their institutions or funders required it, over 80% of them saying they would do it willingly. (Most don't self-archive spontaneously because of worries -- groundless worries -- that it might be illegal or might entail a lot of work.)

(7) Yes, "there are many reasons other than citation rates that make OA worthwhile," but if most researchers will only provide OA if it is mandated, then it is important to demonstrate to researchers why it is worth their while.

(8) If we have given "the impression that mandatory self-archiving of post-prints in institutional repositories is the only reasonable Open Access strategy," then we have succeeded in conveying the implication of our findings.