Wagner AB. Open access citation advantage: an annotated bibliography. Issues in Science and Technology Librarianship; Winter 2010
The publication considers and weighs the evidence on the OA citation impact advantage. It suggests a strong OA citation impact advantage, with a download differential found across studies averaging at least 100%, followed by a citation impact differential of between 25-250% in favour of open access for the majority of studies, and particularly for larger studies, with a minority of studies finding no effect. Possible explanations for these anomalies include small sample size (one study refers to an a statistically insignificant OA impact advantage), disciplinary citation patterns, and failure to allow sufficient time to observe the citation impact difference. As the author points out - no studies found a citation disadvantage for OA.