RESEARCH ARTICLE Open Access Meets Discoverability: Citations to Articles Posted to Academia.edu Yuri Niyazov 1 , Carl Vogel 2 , Richard Price 1 *, Ben Lund 1 , David Judd 1 , Adnan Akil 1 , Michael Mortonson 1 , Josh Schwartzman 1 , Max Shron 2 1 Academia.edu, San Francisco, California, United States of America, 2 Polynumeral, New York, New York, United States of America * richard@academia.edu Abstract Using matching and regression analyses, we measure the difference in citations between articles posted to Academia.edu and other articles from similar journals, controlling for field, impact factor, and other variables. Based on a sample size of 31,216 papers, we find that a paper in a median impact factor journal uploaded to Academia.edu receives 16% more cita- tions after one year than a similar article not available online, 51% more citations after three years, and 69% after five years. We also found that articles also posted to Academia.edu had 58% more citations than articles only posted to other online venues, such as personal and departmental home pages, after five years. Introduction Academia.edu is a website where researchers can post their articles and discover and read arti- cles posted by others. It combines the archival role of repositories like ArXiv, SSRN, or PubMed with social networking features, such as profiles, news feeds, recommendations, and the ability to follow individuals and topics. The site launched in 2008 and as of January 2016 has approxi- mately 30 million registered users who have uploaded approximately 8.5 million articles. Regis- tration on the site is free and users can freely download all papers posted to the site. There is a large body of research on the citation advantage of open access articles, and researchers are still debating the size and causes of the advantage. Some studies have found that open access articles receive substantially more citations than pay-for-access articles, even after controlling for characteristics of the articles and their authors [1, 2]. Other studies using experimental and quasi-experimental methods have concluded that any measured citation advantage is mostly due to selection bias and other unobserved differences between free and paid articles [3–5]. Both the supportive and critical studies have focused on the accessibility of articles: once found, can the article be obtained for free? They have given less consideration to the discover- ability of articles: how easily can the article be found? This makes sense; the methods research- ers often use to find articles don’t privilege open access over paid sources or vice versa. Google Scholar, for example, returns both free and paid sources, as do many library databases. PLOS ONE | DOI:10.1371/journal.pone.0148257 February 17, 2016 1 / 23 OPEN ACCESS Citation: Niyazov Y, Vogel C, Price R, Lund B, Judd D, Akil A, et al. (2016) Open Access Meets Discoverability: Citations to Articles Posted to Academia.edu. PLoS ONE 11(2): e0148257. doi:10.1371/journal.pone.0148257 Editor: Pablo Dorta-González, Universidad de Las Palmas de Gran Canaria, SPAIN Received: August 31, 2015 Accepted: January 15, 2016 Published: February 17, 2016 Copyright: © 2016 Niyazov et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: Data from the "Open Access Meets Discoverability" paper are available at https://github.com/polynumeral/academia-citations. Funding: Academia.edu paid its employees, contractors and an external consultancy (Polynumeral) to perform this study. Authors Yuri Niyazov, Richard Price, Ben Lund, David Judd, Adnan Akil, Michael Mortonson and Josh Schwartzman are employed by Academia.edu. Authors Carl Vogel and Max Shron are employed by Polynumeral. Academia.edu provided support in the form of salaries for authors YN, RP, BL, DJ, AA, MM and JS, but did not have any additional role in the