Methods for estimating the size of Google Scholar

Abstract

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 to 165 million documents. However, all the methods show considerable limitations and uncertainties due to inconsistencies in the Google Scholar search functionalities.

22 pages, 4 figures and 6 tables. arXiv admin note: text overlap with arXiv:1407.6239

References in corpus (2)

• Methods for estimating the size of Google Scholar
• Ranking journals: Could Google Scholar Metrics be an alternative to Journal Citation Reports and Scimago Journal Rank?

Cited by in corpus (4)

• Methods for estimating the size of Google Scholar
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• On Low Overlap Among Search Results of Academic Search Engines
• Could freely available articles reduce faculty reliance on library for access? An analysis of items cited by faculty from Singapore Management University