Citation Advantages of Open Access Articles
PLoS Biology, v.4, May 2006, p.692-698
Abstract:"Open access (OA) to the research literature has the potential to accelerate recognition and dissemination of research findings, but its actual effects are controversial. This was a longitudinal bibliometric analysis of a cohort of OA and non-OA articles published between June 8, 2004, and December 20, 2004, in the same journal (PNAS: Proceedings of the National Academy of Sciences). Article characteristics were extracted, and citation data were compared between the two groups at three different points in time: at "quasi-baseline" (December 2004, 0-6 mo after publication), in April 2005 (4-10 mo after publication), and in October 2005 (10-16 mo after publication). Potentially confounding variables, including number of authors, authors' lifetime publication count and impact, submission track, country of corresponding author, funding organization, and discipline, were adjusted for in logistic and linear multiple regression models. A total of 1,492 original research articles were analyzed: 212 (14.2% of all articles) were OA articles paid by the author, and 1,280 (85.8%) were non-OA articles. In April 2005 (mean 206 d after publication), 627 (49.0%) of the non-OA articles versus 78 (36.8%) of the OA articles were not cited (relative risk = 1.3 [95% Confidence Interval: 1.1-1.6]; p = 0.001). 6 mo later (mean 288 d after publication), non-OA articles were still more likely to be uncited (non-OA: 172 [13.6%], OA: 11 [5.2%]; relative risk = 2.6 [1.4-4.7]; p<0.001).the sd =" 2.5]" sd =" 2.0];" z =" 3.123;" p =" 0.002;" sd =" 10.4]" sd =" 4.9];" z =" 4.058;" ratio =" 2.1">
I find it surprising that there would be a significant increase in citations from papers in an open-access journal, since it is very probable that people who would be citing papers would already have access through their research institution.
The authors seem to have included a substantial number of controls, and also briefly examined self-archived journals, such as those that are on an author's website or can be obtained through Google or other internet site.
The authors briefly discuss in the conclusion below how more papers/journals might become open access:
"OA journals and hybrid journals like PNAS, as well as traditional publishers like Blackwell Publishing (“Online Open”), Oxford University Press (“Oxford Open”), and Springer (“Springer Open Choice”) are now offering authors an immediate OA option if the author pays a fee. Researchers, publishers, and policymakers confronted with the question of whether or not to invest in OA publishing have reason to believe that OA accelerates scientific advancement and knowledge translation of research into practice. While more work remains to be done to evaluate citation patterns over longer periods of time and in different fields and journals, this study provides evidence and new arguments for scientists and granting agencies to invest money into article processing fees to cover the costs of OA publishing. It also provides an incentive for publishers seeking to increase their impact factor to offer an OA option.