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 publishing patterns in biomedicine and researcher access to the biomedical literature. Using ~1 million NIH articles and several matched comparison samples, I 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 the mandate did not induce widespread discrimination, by subscription-based journals, against NIH articles. I also find that the mandate did not increase the number of forward citations to NIH articles published in subscription-based journals. 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.