The Effect of Open Access on Citation Rates of Self-Archived Articles at Chalmers

Open Access (OA) proponents argue that OA increases the visibility and accessibility of research articles, and therefore increases the citation rate of these works. During the last decade numerous studies have been made on the possible citation advantage of OA on scholarly publications. At Chalmers University of Technology (Göteborg, Sweden) an OA policy was adopted in 2010, mandating all of its publications to be self-archived in the university repository Chalmers Publication Library (CPL). One of the arguments of the then vice chancellor was that OA would increase citations. In this study, a possible OA citation advantage of articles self-archived in CPL is examined. A total of 3424 original articles published 2010-2012 were included, 899 of which were published in full text in CPL, and 2571 that were only registered with bibliographical data. Mean normalized citation scores (MNCS) were calculated using Web of Science citation data processed by the Centre for Science and Technology Studies (CWTS) of Leiden University. Results show that self-archived articles have a 22% higher citation rate than articles that were not self-archived, and that the difference is statistically significant. The limitations and biases of the study are also discussed.