Abstract
Purpose: :
To determine impact of free access to journal articles on citations by comparing the number of citations to articles freely available to the average number of citations to articles in the same journals.
Methods: :
We used PubMed limits for ‘free full text’ and ‘PubMed Central’ to identify articles published from 2003-07 in journals with 2008 impact factors (Journal Citation Reports) which are available without subscription. Those articles were searched in Web of Science (Science Citation Index); citations occurring in 2008 were tabulated for each article. The average number of citations to the freely available articles were determined and compared to the 2008 5-year impact factor, which is the average number of citations in 2008 to articles published in 2003-2007. We did not examine citations to articles published in journals in which all content is immediately free, nor in which all content was free for the period under study.
Results: :
Approximately half of the vision journals with 2008 impact factors were found to have no free content. For the others, average citation counts equalled or exceeded the 5-year impact factor for the journal.
Conclusions: :
This is the first study to compare citations to free vs subscription-based content of vision journals, using paid content in the same journal as the control. Articles published in the same journal are more likely to have similar quality characteristics; this study thus demonstrates the value of open access in disseminating research findings. During the period under study, several funder mandates have taken effect; open access journals and open access options such as PubMed Central and institutional repositories have become readily available for wide dissemination of research, as is funding to support fees associated with some open access schemes.
Keywords: clinical (human) or epidemiologic studies: systems/equipment/techniques