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.

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

Suitability of Google Scholar as a source of scientific information and as a source of data for scientific evaluation—Review of the Literature

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 (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 Web of Science 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.

/pdf/google-scholar-microsoft-academic-scopus-dimensions-web-of-3g1le6d0ew.pdf

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

Paper accepted for publication at the Journal of the American Society for Information Science and Technology. http://www.asis.org/jasist.html

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The Google scholar experiment: How to index false papers and manipulate bibliometric indicators

We present a large-scale comparison of five multidisciplinary bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic. The comparison considers all 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.

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

The launch of Google Scholar Metrics as a tool for assessing scientific journals may be serious competition for Thomson Reuters' Journal Citation Reports, and for Scopus' powered Scimago Journal Rank. , A review of these bibliometric journal evaluation products is performed. We compare their main characteristics from different approaches: coverage, indexing policies, search and visualization, bibliometric indicators, results analysis options, economic cost and differences in their ranking of journals. Despite its shortcomings, Google Scholar Metrics is a helpful tool for authors and editors in identifying core journals. As an increasingly useful tool for ranking scientific journals, it may also challenge established journals products.

Ranking journals: could Google Scholar Metrics be an alternative to Journal Citation Reports and Scimago Journal Rank?

The overarching aim of this work is to provide a detailed description of the free version of Dimensions (new bibliographic database produced by Digital Science and launched in January 2018). To do this, the work is divided into two differentiated blocks. First, its characteristics, operation, and features are described, focusing on its main strengths and weaknesses. Secondly, an analysis of its coverage is carried out (comparing it against Web of Science Core Collection, Scopus and Google Scholar) in order to determine whether the bibliometric indicators offered by Dimensions have an order of magnitude significant enough to be used. To this end, an analysis is carried out at three levels: journals (sample of 20 publications in ‘Library & Information Science’), documents (276 articles published by the Journal of informetrics between 2013 and 2015), and authors (28 people awarded with the Derek de Solla Price prize). Preliminary results indicate that Dimensions has coverage of the recent literature superior to Scopus, although inferior to Google Scholar. With regard to the number of citations received, Dimensions offers slightly lower figures than Scopus. Despite this, the number of citations in Dimensions exhibits a strong correlation with Scopus and somewhat less (although still significant) with Google Scholar. For this reason, it is concluded that Dimensions is an alternative for carrying out citation studies, able to rival Scopus (greater coverage and free of charge) and Google Scholar (greater functionalities for the treatment and data export).

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Dimensions: re-discovering the ecosystem of scientific information

/pdf/la-investigacion-en-biblioteconomia-y-documentacion-2m3qnablzy.pdf

La investigación en Biblioteconomía y Documentación.

Introduction and objective. I analyze the repercussions of standardization of scientific publications in general, and of journals in particular, on the processes of scientific information transfer, diffusion and evaluation. Development. Standardization facilitates the work of all agents in the primary (authors, publishers and readers) and secondary communication systems (librarians, information scientifics). Compliance with standards influences the presence of journal in bibliographic databases and de quality of bibliometric studies. Standardization thus has repercussions in the evaluation of science

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Incidencia de la normalización de las revistas científicasen la transferencia y evaluación de la información científica

This letter is a call to the Spanish scientific authorities to abandon current research evaluation policies, which are based on an excessive and indiscriminate use of bibliometric indicators for nearly all areas of scientific activity. This narrow evaluation focus is especially applied to assess the individual performance of researchers. To this end, we first describe the contexts in which the journal impact factor (JIF) and other bibliometric indicators are being used. We then consider the toxic effects of this abuse of indicators. Finally, we outline some significant transformations and initiatives being introduced in various academic fields and regions of the world. These international initiatives offer alternatives to bibliometrics that can improve evaluation processes, and we urge political leaders in Spain to adopt and develop them.

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Emilio Delgado-López-Cózar

Papers

Ranking journals: could Google Scholar Metrics be an alternative to Journal Citation Reports and Scimago Journal Rank?

Dimensions: re-discovering the ecosystem of scientific information

La investigación en Biblioteconomía y Documentación.

Incidencia de la normalización de las revistas científicasen la transferencia y evaluación de la información científica

Letter: A call for a radical change in research evaluation in Spain