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

Bibliometric methods are used in multiple fields for a variety of purposes, namely for research evaluation. Most bibliometric analyses have in common their data sources: Thomson Reuters' Web of Science (WoS) and Elsevier's Scopus. This research compares the journal coverage of both databases in terms of fields, countries and languages, using Ulrich's extensive periodical directory as a base for comparison. Results indicate that the use of either WoS or Scopus for research evaluation may introduces biases that favor Natural Sciences and Engineering as well as Biomedical Research to the detriment of Social Sciences and Arts and Humanities. Similarly, English-language journals are overrepresented to the detriment of other languages. While both databases share these biases, their coverage differs substantially. As a consequence, the results of bibliometric analyses may vary depending on the database used.