About the size of Google Scholar: playing the numbers

About the size of Google Scholar: playing the numbers

Enrique Orduña-Malea¹, Juan Manuel Ayllón², Alberto Martín-Martín²,

Emilio Delgado López-Cózar²

¹ EC3: Evaluación de la Ciencia y de la Comunicación Científica, Universidad Politécnica de Valencia (Spain)

² EC3: Evaluación de la Ciencia y de la Comunicación Científica, Universidad de Granada (Spain)

ABSTRACT The emergence of academic search engines (Google Scholar and Microsoft Academic Search essentially) has revived and increased the interest in the size of the academic web, since their aspiration is to index the entirety of current academic knowledge. The search engine functionality and human search patterns lead us to believe, sometimes, that what you see in the search engine’s results page is all that really exists. And, even when this is not true, we wonder which information is missing and why. The main objective of this working paper is to calculate the size of Google Scholar at present (May 2014). To do this, we present, apply and discuss up to 4 empirical methods: Khabsa & Giles’s method, an estimate based on empirical data, and estimates based on direct queries and absurd queries. The results, despite providing disparate values, place the estimated size of Google Scholar in about 160 million documents. However, the fact that all methods show great inconsistencies, limitations and uncertainties, makes us wonder why Google does not simply provide this information to the scientific community if the company really knows this figure.

KEYWORDS Google Scholar / Academic Search Engines / Size Estimation methods.

EC3’s Document Serie: EC3 Working Papers Nº 18 Document History Version 2.0, Published on 08 September 2014, Granada

Cited as Orduña-Malea, E.; Ayllón, J.M.; Martín-Martín, A.; Delgado López-Cózar, E. (2014). About the size of Google Scholar: playing the numbers. Granada: EC3  Working Papers, 18: 8 September 2014

Corresponding author Emilio Delgado López-Cózar. edelgado@ugr.es Enrique Orduña-Malea. enorma@upv.es

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