Archives des mots-clés : Microsoft Academic

Why are these publications missing? Uncovering the reasons behind the exclusion of documents in free-access scholarly databases

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Authors : Lorena Delgado-Quirós, Isidro F. Aguillo, Alberto Martín-Martín, Emilio Delgado López-Cózar, Enrique Orduña-Malea, José Luis Ortega

This study analyses the coverage of seven free-access bibliographic databases (Crossref, Dimensions—non-subscription version, Google Scholar, Lens, Microsoft Academic, Scilit, and Semantic Scholar) to identify the potential reasons that might cause the exclusion of scholarly documents and how they could influence coverage.

To do this, 116 k randomly selected bibliographic records from Crossref were used as a baseline. API endpoints and web scraping were used to query each database. The results show that coverage differences are mainly caused by the way each service builds their databases.

While classic bibliographic databases ingest almost the exact same content from Crossref (Lens and Scilit miss 0.1% and 0.2% of the records, respectively), academic search engines present lower coverage (Google Scholar does not find: 9.8%, Semantic Scholar: 10%, and Microsoft Academic: 12%). Coverage differences are mainly attributed to external factors, such as web accessibility and robot exclusion policies (39.2%–46%), and internal requirements that exclude secondary content (6.5%–11.6%).

In the case of Dimensions, the only classic bibliographic database with the lowest coverage (7.6%), internal selection criteria such as the indexation of full books instead of book chapters (65%) and the exclusion of secondary content (15%) are the main motives of missing publications.

URL : Why are these publications missing? Uncovering the reasons behind the exclusion of documents in free-access scholarly databases

DOI : https://doi.org/10.1002/asi.24839

Large-scale comparison of bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic

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Authors : Martijn Visser, Nees Jan van Eck, Ludo Waltman

We present a large-scale comparison of five multidisciplinary bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic. The comparison considers scientific documents from the period 2008-2017 covered by these data sources. Scopus is compared in a pairwise manner with each of the other data sources.

We first analyze differences between the data sources in the coverage of documents, focusing for instance on differences over time, differences per document type, and differences per discipline.

We then study differences in the completeness and accuracy of citation links. Based on our analysis, we discuss strengths and weaknesses of the different data sources. We emphasize the importance of combining a comprehensive coverage of the scientific literature with a flexible set of filters for making selections of the literature.

URL : https://arxiv.org/abs/2005.10732

Google Scholar, Microsoft Academic, Scopus, Dimensions, Web of Science, and OpenCitations’ COCI: a multidisciplinary comparison of coverage via citations

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Authors : Alberto Martín-Martín, Mike Thelwall, Enrique Orduna-Malea, Emilio Delgado López-Cózar

New sources of citation data have recently become available, such as Microsoft Academic, Dimensions, and the OpenCitations Index of CrossRef open DOI-to-DOI citations (COCI). Although these have been compared to the Web of Science Core Collection (WoS), Scopus, or Google Scholar, there is no systematic evidence of their differences across subject categories.

In response, this paper investigates 3,073,351 citations found by these six data sources to 2,515 English-language highly-cited documents published in 2006 from 252 subject categories, expanding and updating the largest previous study. Google Scholar found 88% of all citations, many of which were not found by the other sources, and nearly all citations found by the remaining sources (89–94%).

A similar pattern held within most subject categories. Microsoft Academic is the second largest overall (60% of all citations), including 82% of Scopus citations and 86% of WoS citations. In most categories, Microsoft Academic found more citations than Scopus and WoS (182 and 223 subject categories, respectively), but had coverage gaps in some areas, such as Physics and some Humanities categories. After Scopus, Dimensions is fourth largest (54% of all citations), including 84% of Scopus citations and 88% of WoS citations.

It found more citations than Scopus in 36 categories, more than WoS in 185, and displays some coverage gaps, especially in the Humanities. Following WoS, COCI is the smallest, with 28% of all citations. Google Scholar is still the most comprehensive source. In many subject categories Microsoft Academic and Dimensions are good alternatives to Scopus and WoS in terms of coverage.

DOI : https://doi.org/10.1007/s11192-020-03690-4

The coverage of Microsoft Academic: Analyzing the publication output of a university

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Authors : Sven E. Hug, Martin P. Brändle

This is the first in-depth study on the coverage of Microsoft Academic (MA). The coverage of a verified publication list of a university was analyzed on the level of individual publications in MA, Scopus, and Web of Science (WoS).

Citation counts were analyzed and issues related to data retrieval and data quality were examined. A Perl script was written to retrieve metadata from MA. We find that MA covers journal articles, working papers, and conference items to a substantial extent. MA surpasses Scopus and WoS clearly with respect to book-related document types and conference items but falls slightly behind Scopus with regard to journal articles.

MA shows the same biases as Scopus and WoS with regard to the coverage of the social sciences and humanities, non-English publications, and open-access publications. Rank correlations of citation counts are high between MA and the benchmark databases.

We find that the publication year is correct for 89.5% of all publications and the number of authors for 95.1% of the journal articles. Given the fast and ongoing development of MA, we conclude that MA is on the verge of becoming a bibliometric superpower. However, comprehensive studies on the quality of MA data are still lacking.

URL : https://arxiv.org/abs/1703.05539