The role of arXiv, RePEc, SSRN and PMC in formal scholarly communication


The four major Subject Repositories (SRs), arXiv, Research Papers in Economics (RePEc), Social Science Research Network (SSRN) and PubMed Central (PMC), are all important within their disciplines but no previous study has systematically compared how often they are cited in academic publications. In response, this article reports an analysis of citations to SRs from Scopus publications, 2000 to 2013.


Scopus searches were used to count the number of documents citing the four SRs in each year. A random sample of 384 documents citing the four SRs was then visited to investigate the nature of the citations.


Each SR was most cited within its own subject area but attracted substantial citations from other subject areas, suggesting that they are open to interdisciplinary uses. The proportion of documents citing each SR is continuing to increase rapidly, and the SRs all seem to attract substantial numbers of citations from more than one discipline.

Research limitations/implications

Scopus does not cover all publications, and most citations to documents found in the four SRs presumably cite the published version, when one exists, rather than the repository version.

Practical implications

SRs are continuing to grow and do not seem to be threatened by Institutional Repositories (IRs) and so research managers should encourage their continued use within their core disciplines, including for research that aims at an audience in other disciplines.


This is the first simultaneous analysis of Scopus citations to the four most popular SRs.


The Effect of Free Access on the Diffusion…

The Effect of Free Access on the Diffusion of Scholarly Ideas :

« This study examines a relationship between free access to research articles and the diffusion of their ideas as measured by citation counts. While free access should, in theory, help the diffusion of ideas, many researchers have debated the existence of the benefit of free access: reported empirical findings range from zero or negative effect to an over 300% increase of citations of non-free articles. By using a dataset from the Social Science Research Network (SSRN), an open repository of research articles, and employing a natural experiment that allows the estimation of the value of free access separate from confounding factors such as early viewership and quality differential, this study identifies the causal effect of free access on the citation counts. The natural experiment in this study is that a select group of published articles is posted on SSRN at a time chosen by their authors’ affiliated organizations or SSRN, not by their authors. Using a difference-in-difference method and comparing the citation profiles of the articles before and after the posting time on SSRN against a group of control articles with similar characteristics, I stimated the effect of the SSRN posting on citation counts. The articles posted on SSRN receive more citations even prior to being posted on SSRN, suggesting that they are of higher quality. Their citation counts further increase after being posted, gaining an additional 10-20% of citations. This gain is likely to be caused by the free access that SSRN provides. »