Web of Science, Scopus and Google Scholar: A content comprehensiveness comparison

The research aim for this study was to compare three citation resources with one another to identify the citation resource with the most representative South African scholarly environmental sciences citation coverage. This paper focuses on the results of the content verification process which measured amongst others the citation counts, multiple copies and inconsistencies encountered across the three citation resources ISI Web of Science, Scopus and Google Scholar.

The research, the first phase of a longitudinal study, used a comparative research design method with a purposive, non-probability sample. Data from the South African scholarly environmental sciences journals for the year range 2004-2008 (first phase) were extracted from the three citation resources and compared.

It became evident during the verification process that the citation resources retrieved varied results. The total citation counts indicated that ISI Web of Science (WOS) retrieved the most citation results, followed by Google Scholar (GS) and then Scopus. WOS performed the best with total coverage of the journal sample population and also retrieved the most unique items. The investigation into multiple copies indicated that WOS and Scopus retrieved no duplicates, while GS retrieved multiple copies. Scopus delivered the least inconsistencies regarding content verification and content quality compared to the other two citation resources. Additionally, GS also retrieved the most inconsistencies, with WOS retrieving more inconsistencies than Scopus. Examples of these inconsistencies include author spelling and sequence, volume and issue number.

The findings of the study contribute to the understanding of the completeness of citation results retrieved from different citation resources. In addition it will raise awareness amongst academics to check citations of their work.