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: ...
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)....
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!
Posted by
Peter Suber at 11/10/2006 11:34:00 AM.
The open access movement:
Putting peer-reviewed scientific and scholarly literature
on the internet. Making it available free of charge and
free of most copyright and licensing restrictions.
Removing the barriers to serious research.
I recommend the OA tracking project (OATP) as the best way to stay on top of new OA developments. You can read the OATP feed on a blog-like web page or subscribe to it by RSS, email, or Twitter. You can also help build the feed by tagging new developments you encounter.
