Mandating Access : Assessing the Nih's Public Access Policy

In 2008, the National Institutes of Health (NIH) mandated that the full text of NIH-supported articles be made freely available on PubMed Central (PMC) -- the largest and most commonly used repository of biomedical literature. This paper examines how this "PMC mandate" impacted researcher access to the biomedical literature and publishing patterns in biomedicine. Using ~1 million NIH articles and several matched comparison samples, I find that the mandate did not substantially increase the number of forward citations to NIH articles published in subscription-based journals, even from sub-groups of authors most likely to gain access to such articles after the mandate. This is consistent with researchers having widespread access to the biomedical literature prior to the mandate, leaving little room for the mandate to increase access. I also find that NIH articles are more likely to be published in traditional subscription-based journals (as opposed to "open access" journals) after the mandate. This indicates that any discrimination induced by the mandate, by subscription-based journals against NIH articles, was offset by other factors -- possibly the decisions of editors and submission behavior of authors