Do open access journal articles experience a citation advantage? Results and methodological reflections of an application of multiple measures to an analysis by WoS subject areas

Abstract This study is one of the first that uses the recently introduced open access (OA) labels in the Web of Science (WoS) metadata to investigate whether OA articles published in Directory of Open Access Journals (DOAJ) listed journals experience a citation advantage in comparison to subscription journal articles, specifically those of which no self-archived versions are available. Bibliometric data on all articles and reviews indexed in WoS, and published from 2013 to 2015, were analysed. In addition to normalised citation score (NCS), we used two additional measures of citation advantage: whether an article was cited at all; and whether an article is among the most frequently cited percentile of articles within its respective subject area (pptopX %). For each WoS subject area, the strength of the relationship between access status (whether an article was published in an OA journal) and each of these three measures was calculated. We found that OA journal articles experience a citation advantage in very few subject areas and, in most of these subject areas, the citation advantage was found on only a single measure of citation advantage, namely whether the article was cited at all. Our results lead us to conclude that access status accounts for little of the variability in the number of citations an article accumulates. The methodology and the calculations that were used in this study are described in detail and we believe that the lessons we learnt, and the recommendations we make, will be of much use to future researchers interested in using the WoS OA labels, and to the field of citation advantage in general.