Methods for estimating the size of Google Scholar

The emergence of academic search engines (mainly Google Scholar and Microsoft Academic Search) that aspire to index the entirety of current academic knowledge has revived and increased interest in the size of the academic web. The main objective of this paper is to propose various methods to estimat...

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Detalles Bibliográficos
Autores: Orduña-Malea, Enrique|||0000-0002-1989-8477, Ayllon, Juan M., Martín-Martín, Alberto, Delgado-López-Cózar, Emilio
Tipo de recurso: artículo
Fecha de publicación:2015
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:10251/82263
Acceso en línea:https://riunet.upv.es/handle/10251/82263
Access Level:acceso abierto
Palabra clave:Academic search engines
Google Scholar
Estimation method
Size
Coverage
Webometrics
COMUNICACION AUDIOVISUAL Y PUBLICIDAD
BIBLIOTECONOMIA Y DOCUMENTACION
Descripción
Sumario:The emergence of academic search engines (mainly Google Scholar and Microsoft Academic Search) that aspire to index the entirety of current academic knowledge has revived and increased interest in the size of the academic web. The main objective of this paper is to propose various methods to estimate the current size (number of indexed documents) of Google Scholar (May 2014) and to determine its validity, precision and reliability. To do this, we present, apply and discuss three empirical methods: an external estimate based on empirical studies of Google Scholar coverage, and two internal estimate methods based on direct, empty and absurd queries, respectively. The results, despite providing disparate values, place the estimated size of Google Scholar at around 160-165 million documents. However, all the methods show considerable limitations and uncertainties due to inconsistencies in the Google Scholar search functionalities.