Yes, as noted, the three first ranks go to “thematic” (i.e., discipline- or or subject-based) Central Repositories (CRs): (1) Arxiv (Physics), (2) Repec (Economics) and (3) E-Lis (Library Science). That is to be expected, because such CRs are fed from institutions all over the world.
But the fourth-ranked repository — and the first of the university-based Institutional Repositories (IRs), displaying only its own institutional output — is (4) U Southampton EPrints (even though Southampton’s University rank is 77th).
Moreover, the fifteenth place repository — and the first of the department-based IRs — is (15) U Southampton ECS EPrints (making it 10th ranked even relative to university-wide IRs!).
But Southampton’s ECS also adopted the world’s first Green OA self-archiving mandate, now also being emulated worldwide. And that first mandate was a departmental mandate, which partly explains the remarkably high rank of Southampton’s ECS departmental IR.
But these repository rankings (by Webometrics as well as by ROAR) should be interpreted with caution, because not all the CRs and IRs contain full-texts. Some only contain metadata. Southampton’s university-wide IR, although 4th among repositories and 1st among IRs, is still mostly just metadata, because the university-wide mandate that U. Southampton has since adopted still has not been officially announced or implemented (because the university had been preparing for the 2008 Research Assessment Exercise returns). As soon as the mandate is implemented, that will change. (Southampton’s ECS departmental IR, in contrast, mandated since 2002, is already virtually 100% full-text.)
But the moral of the story is that what Southampton is right now enjoying is not just the well-earned visibility of its research output, but also a competitive advantage over other institutions, because of its head-start, both in creating IRs and in adopting a mandate to fill them. (This head-start is also reflected in Southampton’s unusually high University Metrics “G Factor,” and probably in its University Webometric rank too. Citebase is likewise constrained by who has and has not begun to systematically self-archive. And Citeseer has alas stopped updating as of about 2003.)
I am not saying all this by way of bragging! I am begging other institutions to take advantage of the fact that it’s still early days: Get a competitive head start too — by creating an IR, and, most important of all, by adopting a Green OA self-archiving mandate!
American Scientist Open Access Forum