Comparison of self-citation patterns in WoS and Scopus databases based on national scientific production in Slovenia (1996–2020)

Abstract

Comparative studies of Web of Science and Scopus databases relate mainly to journal coverage and citation indicators. The aim of this study is to compare self-citation patterns in these databases. 25 years of scientific production (1996–2020) in Slovenia was analyzed. To offset limitations and errors of deriving data directly from databases, we used the COBISS/SciMet portal, which systematically collects records of citations with various authors identifiers for the total national scientific production. Both databases were harmonized according to the Frascati/OECD classification scheme of research fields. Self-citations were determined by comparing author identifiers rather than their names. Scopus shows better results in self-citation counts. This is mainly due to its higher coverage of local academic journals published in Slovenia and other regional journals, mostly in Humanities, where a fifth of all documents received about 3% more self-citations. In Engineering & Technology and Social Sciences, about 4% and 3% of all documents received approximately 2% more self-citations. However, these differences cause less than 3% more self-citations per researchers and two databases did not substantially differ in the relative citation ranking of researchers. Also, similar patterns of faster ageing of self-citations, rather than citations, were found in both databases, indicating a similar diminishing impact of self-citations on citations over time for all fields.