A longitudinal comparison of citation rates and growth among open access journals

The study documents the growth in the number of journals and articles along with the increase in normalized citation rates of open access (OA) journals listed in the Scopus bibliographic database between 1999 and 2010. Longitudinal statistics on growth in journals/articles and citation rates are broken down by funding model, discipline, and whether the journal was launched or had converted to OA. The data were retrieved from the web sites of SCIMago Journal and Country Rank (journal /article counts), JournalM3trics (SNIP2 values), Scopus (journal discipline) and Directory of Open Access Journals (DOAJ) (OA and funding status). OA journals/articles have grown much faster than subscription journals but still make up less that 12% of the journals in Scopus. Two-year citation averages for journals funded by article processing charges (APCs) have reached the same level as subscription journals. Citation averages of OA journals funded by other means continue to lag well behind OA journals funded by APCs and subscription journals. We hypothesize this is less an issue of quality than due to the fact that such journals are commonly published in languages other than English and tend to be located outside the four major publishing countries.