Proportion Open Access in Biomedical Sciences

Comments on:

Matsubayashi, Mamiko and Kurata, Keiko and Sakai, Yukiko and Morioka, Tomoko and Kato, Shinya and Mine, Shinji and Ueda, Shuichi (2006) Current Status of Open Access in Biomedical Field - the Comparison of Countries Related to the Impact of National Policies. 2006 Annual Meeting of the American Society for Information Science and Technology, Austin, Texas.

This study randomly sampled 4756 biomedical articles published between January and September in 2005 and indexed in PubMed, hand-checking how many of them were OA, and if so how: via OA journal (gold) or self-archiving (green, via IRs or websites). Its findings:

75% of the sampled 4756 articles were available online.
25% of the sampled 4756 articles were OA.

Over 70% of the 1189 (25%) OA articles were OA via OA or Hybrid OA journals
10.9% of the 1189 (25%) OA articles were OA via IRs or websites (6.0% and 4.9% respectively).

20.6% of the articles in journals with an Impact Factor were OA.
30.8% of the articles in journals with no Impact Factor were OA.

Countries were compared, but the variation is more likely in national practices than in national policies.

The authors note that their 25% OA estimate in biomedical sciences in 2005 is higher than Hajjem et al's s estimate of 15% OA in biology and 6% OA in health (but Hajjem et al's sample was for 1992-2003, based only on articles indexed by Thompson ISI, and explicitly excluded articles published in OA journals, hence the relevant comparison figure is the present study's 10.9% for self-archiving).

The authors also note that their estimate of 10.9% self-archiving is lower than Swan's estimate of 49% (but Swan's sample was for all disciplines, and the 49% referred only to the proportion of respondents who had self-archived at least one article).

Presumably "articles in journals that had an Impact Factor" means articles in journals indexed by Thompson ISI. If so, then the finding that fewer ISI articles are OA means that fewer ISI journals are OA and/or fewer authors of articles in non-ISI journals self-archive.

There is considerable scope for variability here (by year, by field, by quality, and by country), but it is certainly true that fewer ISI journals than non-ISI journals are OA (though "Hybrid OA"/Open-Choice may change that).

Several studies -- from Lawrence 2001 to Hajjem et al 2005 -- have reported that there is a positive correlation between citation-bracket and OA (the higher the citations, the more likely the article is OA), and there is disagreement over how much of this effect is a causal Quality Advantage (OA causing higher citations for higher quality articles) or a self-selection Quality Bias (authors of higher quality articles being more likely to make them OA, one way or the other). The present results don't resolve this, as they go both ways.

Clearly, more studies are needed. But even more than that, more OA is needed!

      References
      Hajjem, C., Harnad, S. and Gingras, Y. (2005) Ten-Year Cross-Disciplinary Comparison of the Growth of Open Access and How it Increases Research Citation Impact. IEEE Data Engineering Bulletin 28(4) pp. 39-47.
      Swan, A. (2006) The culture of Open Access: researchers' views and responses, in Jacobs, N., Eds. Open Access: Key Strategic, Technical and Economic Aspects, chapter 7. Chandos.

Stevan Harnad
American Scientist Open Access Forum