Google Scholar, Web of Science, and Scopus: A systematic comparison of citations in 252 subject categories

[EN] Despite citation counts from Google Scholar (GS), Web of Science (WoS), and Scopus being widely consulted by researchers and sometimes used in research evaluations, there is no recent or systematic evidence about the differences between them. In response, this paper investigates 2,448,055 citat...

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Detalles Bibliográficos
Autores: Martín-Martín, Alberto, Thelwall, Mike, Delgado Lopez-Cozar, Emilio, Orduña-Malea, Enrique|||0000-0002-1989-8477
Tipo de recurso: artículo
Fecha de publicación:2018
País:España
Institución:Universitat Politècnica de València (UPV)
Repositorio:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
Idioma:inglés
OAI Identifier:oai:riunet.upv.es:10251/154398
Acceso en línea:https://riunet.upv.es/handle/10251/154398
Access Level:acceso abierto
Palabra clave:Google Scholar
Web of Science
Scopus
Bibliographic databases
Academic search engines
Coverage
Citation analysis
Unique citations
Citation overlap
Bibliometrics
Scientometrics
BIBLIOTECONOMIA Y DOCUMENTACION
Descripción
Sumario:[EN] Despite citation counts from Google Scholar (GS), Web of Science (WoS), and Scopus being widely consulted by researchers and sometimes used in research evaluations, there is no recent or systematic evidence about the differences between them. In response, this paper investigates 2,448,055 citations to 2299 English-language highly-cited documents from 252 GS subject categories published in 2006, comparing GS, the WoS Core Collection, and Scopus. GS consistently found the largest percentage of citations across all areas (93%¿96%), far ahead of Scopus (35%¿77%) and WoS (27%¿73%). GS found nearly all the WoS (95%) and Scopus (92%) citations. Most citations found only by GS were from non-journal sources (48%¿65%), including theses, books, conference papers, and unpublished materials. Many were non-English (19%¿38%), and they tended to be much less cited than citing sources that were also in Scopus or WoS. Despite the many unique GS citing sources, Spearman correlations between citation counts in GS and WoS or Scopus are high (0.78-0.99). They are lower in the Humanities, and lower between GS and WoS than between GS and Scopus. The results suggest that in all areas GS citation data is essentially a superset of WoS and Scopus, with substantial extra coverage.