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The comparative recall of Google Scholar versus PubMed in identical searches for biomedical systematic reviews: a review of searches used in systematic reviews
Open accessAbstract
BACKGROUND: The usefulness of Google Scholar (GS) as a bibliographic database for biomedical systematic review (SR) searching is a subject of current interest and debate in research circles. Recent research has suggested GS might even be used alone in SR searching. This assertion is challenged here by testing whether GS can locate all studies included in 21 previously published SRs. Second, it examines the recall of GS, taking into account the maximum number of items that can be viewed, and tests whether more complete searches created by an information specialist will improve recall compared to the searches used in the 21 published SRs. METHODS: The authors identified 21 biomedical SRs that had used GS and PubMed as information sources and reported their use of identical, reproducible search strategies in both databases. These search strategies were rerun in GS and PubMed, and analyzed as to their coverage and recall. Efforts were made to improve searches that underperformed in each database. RESULTS: GS' overall coverage was higher than PubMed (98% versus 91%) and overall recall is higher in GS: 80% of the references included in the 21 SRs were returned by the original searches in GS versus 68% in PubMed. Only 72% of the included references could be used as they were listed among the first 1,000 hits (the maximum number shown). Practical precision (the number of included references retrieved in the first 1,000, divided by 1,000) was on average 1.9%, which is only slightly lower than in other published SRs. Improving searches with the lowest recall resulted in an increase in recall from 48% to 66% in GS and, in PubMed, from 60% to 85%. CONCLUSIONS: Although its coverage and precision are acceptable, GS, because of its incomplete recall, should not be used as a single source in SR searching. A specialized, curated medical database such as PubMed provides experienced searchers with tools and functionality that help improve recall, and numerous options in order to optimize precision. Searches for SRs should be performed by experienced searchers creating searches that maximize recall for as many databases as deemed necessary by the search expert.
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“Previous studies have also calculated precision and recall of search systems from data reported by specific evidence‐synthesis studies.24, 32, 33, 34”
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“Quality criteria have previously been used to evaluate search systems in terms of recall and precision indicating their suitability of search in general and systematic search in particular.”
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“The distinction between principal and supplementary resources for systematic reviews was also used in previous assessments of search system qualities.33, 57”
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“Until now, studies have largely examined the suitability of search systems for certain scholarly tasks for individual systems or by comparing a few systems.33, 50, 95”
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“Our findings support the criticism of Bramer et al,33 Bramer et al,34 and Boeker et al25 and indicate that Google Scholar's coverage and recall is an inadequate reason to use it as principal search system in systematic searches.53”
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Cited by
Sorted by citations
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“33,50,95 Our methods allowed a comprehensive review of many different search systems.”
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“Nevertheless others have concluded that a single database is not sufficient to retrieve all references for systematic reviews [18, 19].”
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Metadata
- Authors
- Bramer, W. M., Giustini, D., Kramer, B. M., & Anderson, P.
- Affiliations
- Erasmus MC (NL)
- University of British Columbia (CA)
- Utrecht University (NL)
- Corresponding author
- Bramer, Wichor M
- Venue
- Systematic Reviews
- Published
- 2013-12
- Volume
- 2
- Issue
- 1
- Pages
- 115-115
- ISSN
- 2046-4053 (ISSN-L)
- PMC
- PMC3882110
- OpenAlex
- W2100684744
- Cited by
- 139
- References
- 33
- Citations by year
- 2026: 5 · 2025: 11 · 2024: 11 · 2023: 5 · 2022: 16 · 2021: 13 · 2020: 10 · 2019: 17 · 2018: 7 · 2017: 15 · 2016: 15 · 2015: 10 · 2014: 4
- FWCI
- 1.98
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Systematic Reviews (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- RePub (Erasmus University Rotterdam) (submittedVersion, other-oa)
- cIRcle (University of British Columbia) (submittedVersion, cc-by)
- Deep Blue (University of Michigan) (submittedVersion)
- RePub (Erasmus University Rotterdam) (submittedVersion)
- Topics
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Computer Science › Information Systems › Information Retrieval and Search Behavior
- Social Sciences › Library and Information Sciences › scientometrics and bibliometrics research
- Keywords
- Google Scholar, PubMed, search precision, information retrieval, database comparison
- MeSH terms
- Systematic Reviews as Topic, Humans, Information Storage and Retrieval, Internet, PubMed, Search Engine
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