G Model RESPOL 2590 1–7 ARTICLE IN PRESS Research Policy xxx (2011) xxx–xxx 1 Contents lists available at ScienceDirect Research Policy jou rnal homepage: www.elsevier.com/locate/respol ଝ 1 Getting cited: Does open access help? 1 2 Patrick Gaulé ∗, Nicolas Maystre 3 Sloan School of Management, Massachusetts Institute of Technology, MA, United States 4 5 a r t i c l e i n f o a b s t r a c t 6 7 Article history: Cross-sectional studies typically find positive correlations between free availability of scientific articles 8 Received 6 November 2010 (‘open access’) and citations. Using a number of instruments as plausible sources of exogeneous variation, 9 Received in revised form 1 April 2011 we find no evidence for a causal effect of open access on citations. We provide theory and evidence 10 Accepted 27 May 2011 suggesting that authors of higher quality papers are more likely to choose open access in hybrid journals Available online xxx which offer an open access option. Self-selection mechanisms may thus explain the discrepancy between 11 the positive correlation found in Eysenbach (2006) and other cross-sectional studies and the absence of 12 Keywords: such correlation in the field experiment of Davis et al. (2008). 13 Open access © 2011 Elsevier B.V. All rights reserved. 14 Q3 Knowledge diffusion 15 Scientific publishing 16 Citations 17 1. Introduction Science and its flagship journals, PLoS Biology and PLoS Medicine, are 31 perhaps the most notable examples but the directory of open access 32 18 The dominant business model in scientific publishing is ‘reader journals currently lists more than 3000 entries. Despite concerns 33 19 pays’, i.e. university libraries pay for academic journals through that open access journals may be of lower quality (Jeon and Rochet., 34 20 subscriptions. However, scientific articles are increasingly avail- 2007; McCabe and Snyder, 2006), some have established them- 35 21 able for free (‘open access’) under different modalities. Three factors selves as prestigious outlets. For instance, the open access journal 36 22 have facilitated the emergence of open access: sharp decreases in PLoS Pathogens has an impact factor above nine and is the leading 37 23 dissemination costs with the advent of electronic publishing, grow- journal in the field of parasitology. 38 24 ing expectations that the results of publicly funded research should Separately, publishers are increasingly offering authors the pos- 39 25 be freely available and increased strains on library budgets associ- sibility to buy open access to their articles in subscription-based 40 26 ated with substantial increases in journal prices (McCabe, 2002; journals. Initially pioneered by a number of not-for-profit pub- 41 27 Dewatripont et al., 2006). lishers, open access options are now offered by almost all major 42 1 28 The most visible form of open access has been the creation of publishers. 43 29 journals that are free for readers and financed through fees levied Free online availability can also result from authors posting 44 30 on authors upon submission. The journals of the Public Library of versions of their papers on their websites or in institutional reposi- 45 tories. This type of open access has become increasingly important 46 with the adoption of institutional mandates. For instance, the pub- 47 lic access policy of the National Institutes of Health (NIH) requires 48 ଝ We thank seminar participants at the University of Geneva, the Graduate authors of research funded by NIH to make their papers available 49 Institute for International and Development studies, the EPFL, the CUSO doctoral for free to the public on PubMed Central no later than 12 months 50 workshop, the University of Munich, Bocconi University, the AEA 2010 conference and the ‘Economic Perspectives on Scholarly Communication in a Digital Age’ work- after publication. 51 shop at the University of Michigan for interaction and comments. We are indebted to an anonymous referee, Stephen Bazen, Annamaria Conti, Philip Davis, Mathias Dewatripont, Jaime de Melo, Chiara Franzoni, Marco Fugazza, Alfonso Gambardella, Bronwyn Hall, Jaya Krishnakumar, Rafael Lalive, Francisco Lissoni, Christopher 1 Liu, Jacques Mairesse, Thierry Mayer, Fabio Montobbio, Mario Piacentini, Gilbert The Entomological Society of America and the American Society of Limnology Ritschard, Jean-Charles Rochet, Dominic Rohner, Cédric Tille, Alexis Walckiers and and Oceanography were among the first to sell optional open access, beginning in especially Dominique Foray, Dietmar Harhoff, Bo Honoré, Marcelo Olarreaga, Fred- 2001 (Walker, 2004). The Company of Biologists offers an open access option in its eric Robert-Nicoud and Mathias Thoenig for insightful discussions and advice. journals Development, Journal of Cell Science, Journal of Experimental Biology since ∗ Corresponding author. January 2004. Proceedings of the National Academy of Science started to offer an open E-mail addresses: [email protected] (P. Gaulé), [email protected], access option in May 2004. The major publishers have followed, although not for [email protected] (N. Maystre). all their journals: Elsevier (‘Sponsored articles’), Springer (‘Open Choice’), Black- 1 UN-DESA. The views and opinions expressed herein are those of the author and well (‘Online Open’), Taylor & Francis (‘iOpen Access’), John Wiley & Sons (‘Funded do not necessarily reflect those of the United Nations. Access’), Oxford University Press (‘Oxford open’). 0048-7333/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.respol.2011.05.025 Please cite this article in press as: Gaulé, P., Maystre, N., Getting cited: Does open access help? Res. Policy (2011), doi:10.1016/j.respol.2011.05.025 G Model RESPOL 2590 1–7 ARTICLE IN PRESS 2 P. Gaulé, N. Maystre / Research Policy xxx (2011) xxx–xxx 52 The emergence of open access raises an important and interest- access papers tend to be of higher quality on average. Consequently, 112 53 ing question. Do articles that are freely available get more widely regressions of the number of citations on open access capture both 113 54 diffused as a result? Using citations as a proxy for diffusion, many a diffusion effect and a self-selection effect. 114 55 cross-sectional studies have found a positive correlation between Empirically, we analyze a sample of 4388 biology papers pub- 115 56 open access and citations. The seminal contribution is Lawrence lished between May 2004 and March 2006 by Proceedings of the 116 57 (2001) who finds that computer science conference articles that National Academy of Sciences (PNAS) an important, high-volume 117 58 were openly accessible on the Web were cited more often than scientific journal which started to offer an open access option to 118 59 those that were not (+150%). Studies that find an open access cita- authors in May 2004 for a USD 1000 fee. 119 60 tion advantage by comparing sample means include Walker (2004); In this journal, open access papers receive significantly more 120 61 Antelman (2004); Harnad and Brody (2004), and Norris et al. (2008). citations after controlling for observables, as found in Eysenbach 121 62 A number of papers have investigated the effect on citations of (2006) who favored a diffusion (causal) interpretation. After repli- 122 63 depositing a (free) preprint on arXiv, an archive of working papers cating this cross-sectional correlation using a broader sample, we 123 64 in mathematics and physics (Schwarz and Kennicutt, 2004; Kurtz extend the analysis in multiple ways and reach opposite con- 124 65 et al., 2005; Metcalfe, 2005; Moed, 2007; Davis and Fromerth, clusions. We first find empirical evidence of self-selection using 125 66 2007). While papers deposited on arXiv get cited more, the inter- an original measure of article quality, i.e. the ratings from F1000 126 67 pretation is disputed with the more recent studies attributing biology, a website where biology professors evaluate new papers 127 68 this effect to quality differentials or earlier availability. Evans and of interest. We also implement an instrumental variable strategy 128 69 Reimer (2009) follow a different approach by comparing citations where our preferred instrument is a dummy for publication of the 129 70 before and after scientific publications become freely available and article in the last quarter of the fiscal year. The idea here is that aca- 130 71 find a small effect of open access (around 8%). This study has been demic departments may have unused budgets that must be spent 131 72 criticized by McCabe and Snyder (2011) for failing to take into before the end of the fiscal year (or the funds are lost). Thus, discre- 132 73 account time trends in citations. tionary spending on otherwise low-priority items such as paying 133 74 Perhaps the most influential cross-sectional study is Eysenbach for optional open access fees is more likely to be observed towards 134 75 (2006) who compares the citation rates between open access and the end of the year, which is born out by our data. Using this instru- 135 76 non-open access articles published in the second half of 2004 in Pro- ment, we find that the coefficient of open access is insignificant and 136 77 ceedings of the National Academy of Sciences (PNAS), a journal that dramatically reduced compared to the coefficient of a simple ordi- 137 78 offers an open access option for a fee. The strength of his approach nary least squares regression. Similar results are found with other 138 79 is that he is able to control for important observables that might instruments (and combinations thereof): a change of publication 139 80 affect both the choice of open access and citations. Controlling for policy for NIH intramural researchers and a dummy for Howard 140 81 number of authors, authors’ lifetime publication count and impact, Hughes Medical Institute investigators (who receive a special bud- 141 82 submission track, country of corresponding author, funding organi- get to pay open access fees).