Date of this Version
OANumbr (1): 1 (2016-08-02)
This note presents data from the 1science OAIndx on the average of relative citations (ARC) for 3.3 million papers published from 2007 to 2009 and indexed in the Web of Science (WoS). These data show a decidedly large citation advantage for open access (OA) papers, despite them suffering from a lag in availability compared to paywalled papers.
There is an abundant literature on the citation advantage of OA papers, starting with a succinct communication by Lawrence (2001). Several studies have been listed by SPARC, the majority of which support the idea that when papers are openly available, they are more cited than papers for which availability is restricted to those who pay for access (http://sparceurope.org/oaca/). As noted by Diana Hicks on the ScienceMetrics.org blog (http://sciencemetrics.org/oaca-open-accesscitation- advantage/), skeptics argue that the advantage of OA is partly due to citations having a chance to arrive sooner. Another purported artefact would be a selection bias according to which authors pick their best (hence most citeable) papers to make OA. This paper examines the first aspect and concludes that the purported head start of OA papers is actually contrary to observed data. The limitation of the existing literature on the subject, whether supporting or refuting the OA citation advantage, is often the small number of articles analyzed, the limited size and diversity of the citing sources, and the short citation window considered. The present note examines 3,350,910 papers published between 2007 and 2009 and indexed in the WoS, with a citation window starting in 2007 and continuing up to the latest date possible (in practice, mid-2016). More than 12,000 journals indexed in the WoS were used to compute the citations