Abstract: Cross-sectional studies typically find positive correlations between free availability of scientific articles ('open access') and citations. Using a number of instruments as plausible sources of exogeneous variation, we find no evidence for a causal effect of open access on citations. We provide theory and evidence suggesting that authors of higher quality papers are more likely to choose open access in hybrid journals which offer an open access option. Self-selection mechanisms may thus explain the discrepancy between the positive correlation found in Eysenbach (2006) and other cross-sectional studies and the absence of such correlation in the field experiment of Davis et al. (2008).
Bibliographical noteFunding Information:
Our second instrument is a dummy that takes value 1 if the corresponding author is an intramural researcher of the National Institutes of Health (NIH) and the article was published after April 2005. The NIH issued a new policy on open access in February 2005, to be implemented in May 2005. Although this policy was primarily aimed at research funded by the NIH and conducted extra muros, it also had an effect on NIH intramural researchers. Before the change in policy, only 13% of articles authored by NIH intramural researchers were in open access. After the change in policy, the corresponding number was 28%. Since we control for being a NIH intramural researcher and for time trends, we expect the instrument to capture only the effect of open access. Our third instrument is a dummy that takes value 1 if one of the authors is an investigator for the Howard Hughes Medical Institute (HHMI). The HHMI provides a special budget of USD 3000 to its investigators to pay for open access fees. Since HHMI investigatorships are prestigious, it is important that we control for author quality to ensure the validity of the instrument.
- Knowledge diffusion
- Open access
- Scientific publishing