Google Scholar, Microsoft Academic, Scopus, Dimensions, Web of Science, and OpenCitations’ COCI: a multidisciplinary comparison of coverage via citations

By Alberto Mart'in-Mart'in, Mike Thelwall, Enrique Orduña-Malea, Emilio Delgado López-Cózar. Scientometrics, 2020

1,022 citations recorded by the source corpus.

New sources of citation data have recently become available, such as Microsoft Academic, Dimensions, and the OpenCitations Index of CrossRef open DOI-to-DOI citations (COCI). Although these have been compared to the Web of Science Core Collection (WoS), Scopus, or Google Scholar, there is no systematic evidence of their differences across subject categories. In response, this paper investigates 3,073,351 citations found by these six data sources to 2,515 English-language highly-cited documents published in 2006 from 252 subject categories, expanding and updating the largest previous study. Google Scholar found 88% of all citations, many of which were not found by the other sources, and nearly all citations found by the remaining sources (89–94%). A similar pattern held within most subject categories. Microsoft Academic is the second largest overall (60% of all citations), including 82% of Scopus citations and 86% of WoS citations. In most categories, Microsoft Academic found more citations than Scopus and WoS (182 and 223 subject categories, respectively), but had coverage gaps in some areas, such as Physics and some Humanities categories. After Scopus, Dimensions is fourth largest (54% of all citations), including 84% of Scopus citations and 88% of WoS citations. It found more citations than Scopus in 36 categories, more than WoS in 185, and displays some coverage gaps, especially in the Humanities. Following WoS, COCI is the smallest, with 28% of all citations. Google Scholar is still the most comprehensive source. In many subject categories Microsoft Academic and Dimensions are good alternatives to Scopus and WoS in terms of coverage.

Subfields: History and Philosophy of Science, Information Systems and Management, Statistics and Probability

View Paper: https://www.semanticscholar.org/paper/40885a8e7e1cf2f055054bab418aebb1c673db3b

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Citations in the corpus

Large-scale comparison of bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic (2020, background): “Large-scale studies of Google Scholar (Martín-Martín et al., 2018, 2020) require an extraordinary amount of effort (Else, 2018).”
Exploratory Bibliometrics: Using VOSviewer as a Preliminary Research Tool (2023, methodology): “VOSviewer uses inputs from Web of Science, Scopus and PubMed, all of which are highly regarded in the bibliometric field [19].”
Citationchaser: A tool for transparent and efficient forward and backward citation chasing in systematic searching (2022, background): “Microsoft Academic Graph and CrossRef have been shown to have considerable overlap with traditional resources such as Scopus and Web of Science.”
The journal coverage of Web of Science, Scopus and Dimensions: A comparative analysis (2020, methodology): “Some of the initial studies of direct coverage comparison of different databases are Mayr and Walter (2007), Gavel and Iselid (2008), Lopez-Illescas et al.”
Web of Science (WoS) and Scopus: The Titans of Bibliographic Information in Today's Academic World (2021, background): “However, since both WoS and Scopus are commercial, their content is protected by restricting access to raw data [42], and access to their APIs usually requires additional payment [32].”