The journal coverage of Web of Science and Scopus: a comparative analysis

Results indicate that the use of either WoS or Scopus for research evaluation may introduce biases that favor Natural Sciences and Engineering as well as Biomedical Research to the detriment of Social Sciences and Arts and Humanities.

Abstract

Bibliometric methods are used in multiple fields for a variety of purposes,
\nnamely for research evaluation. Most bibliometric analyses have in common their data
\nsources: Thomson Reuters’ Web of Science (WoS) and Elsevier’s Scopus. The objective of
\nthis research is to describe the journal coverage of those two databases and to assess
\nwhether some field, publishing country and language are over or underrepresented. To do
\nthis we compared the coverage of active scholarly journals in WoS (13,605 journals) and
\nScopus (20,346 journals) with Ulrich’s extensive periodical directory (63,013 journals).
\nResults indicate that the use of either WoS or Scopus for research evaluation may introduce
\nbiases that favor Natural Sciences and Engineering as well as Biomedical Research to the
\ndetriment of Social Sciences and Arts and Humanities. Similarly, English-language journals are overrepresented to the detriment of other languages. While both databases share
\nthese biases, their coverage differs substantially. As a consequence, the results of bibliometric analyses may vary depending on the database used. These results imply that in the
\ncontext of comparative research evaluation, WoS and Scopus should be used with caution,
\nespecially when comparing different fields, institutions, countries or languages. The bibliometric community should continue its efforts to develop methods and indicators that
\ninclude scientific output that are not covered in WoS or Scopus, such as field-specific and
\nnational citation indexes.