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The Journal Coverage of Web of Science, Scopus and Dimensions: A Comparative Analysis
Vivek Kumar Singh, Prashasti Singh, Mousumi Karmakar, Jacqueline Leta, Philipp Mayr
TL;DR
This study addresses limited direct evidence on how Web of Science, Scopus, and Dimensions differ in journal coverage and country-level research outputs. Using master journal lists and publication records for 20 countries, it finds substantially different database coverage, with Web of Science most selective and Dimensions most exhaustive, alongside variations in country results and disciplinary coverage.
Problem
Previous comparisons focused mainly on article coverage or citations, leaving direct comparative evidence on the three databases’ journal coverage limited.
Method
The study compares the three databases’ master journal lists and examines publication records for 20 selected countries across the databases.
Results
The databases differ significantly: Web of Science is most selective, Dimensions most exhaustive, and their coverage differences produce variations in country output volume, rank, global share, and subject areas.
Takeaways & Limitations
Bibliometric evaluations at the country level may produce different outcomes depending on the database used, partly because disciplinary coverage varies across databases.
Takeaways & Limitations
The study uses a conservative journal-matching procedure and excludes books and conference publications from the comparison.
Abstract
from arXiv · showhide
Traditionally, Web of Science and Scopus have been the two most widely used databases for bibliometric analyses. However, during the last few years some new scholarly databases, such as Dimensions, have come up. Several previous studies have compared different databases, either through a direct comparison of article coverage or by comparing the citations across the databases. This article attempts to compare the journal coverage of the three databases: Web of Science, Scopus and Dimensions. The most recent master journal lists of the three databases have been used for the purpose of identifying the overlapping and unique journals covered in the databases. The results indicate that the databases have significantly different journal coverage, with the Web of Science being most selective and Dimensions being the most exhaustive. About 99.11% and 96.61% of the journals indexed in Web of Science are also indexed in Scopus and Dimensions, respectively. Scopus has 96.42% of its indexed journals also covered by Dimensions. Dimensions database has the most exhaustive coverage, with 82.22% more journals covered as compared to Web of Science and 48.17% more journals covered as compared to Scopus. We also analysed the research outputs for 20 highly productive countries for the 2010-2019 period, as indexed in the three databases, and identified database-induced variations in research output volume, rank and global share of different countries. In addition to variations in overall coverage of research output from different countries, the three databases appear to have differential coverage of different disciplines.
A brief overview of the three scholarly databases
Web of Science, Scopus, and Dimensions differ in age, scope, and data architecture. Web of Science and Scopus are citation-oriented scholarly databases, while Dimensions links publications and citations with broader research information from multiple sources.
- Web of Science, created in 1964, is the oldest database and originated as an information retrieval and citation-index tool.
- Web of Science organizes coverage through multiple citation indexes, whereas Scopus uses a single citation index spanning journals and conference articles across subject areas.
- Scopus, created in 2004 by Elsevier, is a curated database covering journals, books, and conference proceedings through continuous content re-evaluation.
- Dimensions, created in 2018, is the newest database and provides linked access to publications, citations, grants, clinical trials, patents, policy documents, and altmetrics.
- Dimensions sources data through Crossref and PubMed, then enhances it with affiliations, citations, and information from additional scholarly and public sources.
Related Work
Previous research compared scholarly databases through journal or article coverage and citation counts. Findings generally showed meaningful differences between Web of Science, Scopus, Google Scholar, and other sources.
- Direct coverage studies examined which journals or articles were indexed across databases, including comparisons involving Web of Science, Scopus, Google Scholar, and other sources.
- Scopus covered more journals than Web of Science in one comprehensive comparison, but its coverage was described as lower-impact and focused on more recent articles.
- Longitudinal comparison found consistent and reasonably stable quarterly growth in publications and citations across Web of Science, Scopus, and Google Scholar.
- Other studies reported that Google Scholar often identified citations absent from Web of Science, while citation differences did not necessarily correspond to database coverage differences.
- Citation comparisons found that Scopus yielded 14.7% more citations than Web of Science for papers from the University of Navarra’s Health Sciences area.
Studies on comparison of newer scholarly databases
Studies of newer scholarly databases found that Dimensions can provide substantial overlap with established sources while offering broader coverage. The present study extends this literature by comparing journal lists and country-level outputs across databases.
- Dimensions covered 97% of Scopus articles with DOIs in a 2012 Food Science sample, with citation counts highly correlated between the two databases.
- A large-scale publication-record comparison found that Dimensions had higher coverage than Web of Science and Scopus, covering about 78% of Scopus publication records.
- Citation analysis across six data sources found Dimensions covered 84% of Scopus citations and 88% of Web of Science citations.
- Data & Methodology: The study uses master journal lists and 2010–2018 publication records for twenty selected countries to compare coverage and indexed research outputs.
- Data & Methodology: The analysis compares overlapping and unique journals, computes country research-output rank, global share, and CAGR, and examines subject-area distributions.
Results
The three databases differ substantially in journal coverage, with extensive pairwise overlaps but also large database-specific collections. The three-way overlap covers most Web of Science journals but much smaller shares of Scopus and Dimensions.
- 99.11% of Web of Science journals overlap with Scopus, compared with 96.61% overlapping with Dimensions; Web of Science has 19 unique journals.
- 96.42% of Scopus journals overlap with Dimensions, while Scopus contains 980 unique journals.
- 82.22% of Dimensions journals do not overlap with Web of Science, and 48.17% do not overlap with Scopus; Dimensions contains 35,528 unique journals.
- 13,047 journals are indexed in all three databases, representing 95.86% of Web of Science, 32.82% of Scopus, and 17.64% of Dimensions.
Analysing research output of different countries in the three databases
The study compares research output for 20 selected countries across the three databases. Database choice changes reported output volume, global share, rank, and growth rates, with notable country-specific exceptions.
- Research output volumes for the same countries vary across databases, with differences reaching 1 million records for the USA and China.
- USA global share is 27.24% in Web of Science, 23.04% in Scopus, and 17.03% in Dimensions.
- Dimensions generally reports higher research output volume than Scopus, which generally exceeds Web of Science, except for China and India.
- Country CAGR values differ across databases, including USA growth of 2.63% in Web of Science versus 4.03% in Dimensions.
Subject area distribution of research output in the three databases
The databases differ not only in overall research-output coverage but also in the subject areas represented for countries and in the aggregate country output. Country profiles commonly emphasize Life Sciences, with notable national exceptions.
- Web of Science’s major subject-area distribution accounts for 44.5% of the combined output of the twenty selected countries.
- Most countries have 40–50% of publications in Life Sciences, while China, Russia, and Taiwan are major exceptions.
- Germany, Japan, France, and India have higher Physical Sciences proportions, while China, India, South Korea, and Taiwan have substantial Technology output.
- China and India have negligible Arts & Humanities output and very low Social Sciences output across all three databases.
- Subject-area proportions for the same country vary across databases, indicating differential coverage of journals by discipline.
Discussion
The study directly compares journal coverage across Web of Science, Scopus, and Dimensions, updating earlier comparisons and examining effects on country and disciplinary research-output patterns.
- The study provides an updated comparison of Web of Science and Scopus using master journal lists updated through June 2020.
- The study is the first direct comparison of Dimensions journal coverage with Web of Science and Scopus, including subject-area distributions.
- The three databases differ substantially in journal coverage, with Web of Science most selective and Dimensions most exhaustive.
- Differences in journal coverage produce variations in countries’ research-output volumes, ranks, and global shares across databases.Some countries, including China and India, have higher research output in Scopus than in Dimensions.
- Dimensions has relatively better coverage of Social Sciences and Arts & Humanities, while Web of Science and Scopus have more similar subject-area coverage.
Conclusion
The study finds major differences in journal coverage among the three databases and shows that these differences affect country-level bibliometric results and disciplinary representation.
- Web of Science has the most selective journal coverage, whereas Dimensions has the most exhaustive coverage.
- 82.22% and 48.17% more unique journals are covered by Dimensions than by Web of Science and Scopus, respectively.
- Different database coverage produces variation in countries’ research-output volumes, ranks, and global shares.Using different databases may therefore produce different outcomes in country-level bibliometric evaluations.
- Dimensions has significantly better coverage of Social Sciences and Arts & Humanities, while Web of Science and Scopus concentrate more on Life Sciences, Physical Sciences, and Technology.
- Database choice may depend on the intended purpose, with Dimensions offering wider coverage and data filters that can limit records to expert-curated or nationally recognized journals.
- The study excludes books and conferences, does not include Web of Science’s Emerging Sources Citation Index, and may miss differently spelled journals through conservative matching.
APPENDIX
The appendix describes preprocessing and sequential matching of the three databases’ master journal lists to identify overlapping and unique journal records.
- Pre-processing: Journal lists were cleaned by removing entries with missing or duplicated ISSN/e-ISSN fields and non-journal sources such as preprints and conference proceedings.
- Pre-processing: After preprocessing, the lists contained 13,610 Web of Science, 39,758 Scopus, and 73,966 Dimensions journal entries.
- ISSN/e-ISSN matching: Matching began with ISSN and e-ISSN fields, using several cross-matching steps to account for exchanged identifiers.
- ISSN/e-ISSN matching: ISSN/e-ISSN matching produced 12,744 Web of Science–Scopus, 11,305 Web of Science–Dimensions, and 23,579 Scopus–Dimensions matching records in the initial step.
- Title matching: Remaining records were matched on journal titles using exact matching followed by cosine-similarity matching with a threshold of 0.9.
- Outcome: The resulting matches were used to identify overlapping and unique journal entries across the three databases.
TABLES
The tables organize the study’s journal counts, publication records, article types, subject-area mapping, and country-level research-output statistics across the three databases.
- Table 1 reports the number of journals and publication records indexed in Web of Science, Scopus, and Dimensions.
- Table 2 presents article-type distributions in the three databases for 2010-18.
- Table 3 maps Scopus and Dimensions subject areas to Web of Science major subject areas.
- Table 4 reports research-output rank, volume, and global share for 20 selected countries during 2010-18.
- Table 5 provides country-wise publication-record data in the three databases for article and review document types, including CAGR values.
FIGURES
The figures visualize journal-overlap patterns, country-level research-output comparisons, and the distribution of combined and individual outputs across the three databases.
- Figure 1 depicts pair-wise journal-coverage overlap among Web of Science, Scopus, and Dimensions.
- Figure 2 depicts journal-coverage overlap across all three databases.
- Figure 3 compares article-and-review research output for 20 countries across the three databases during 2010-18.
- Figure 4 shows the distribution of combined article-and-review research output for 20 countries across the three databases during 2010-18.
- Figure 5 shows the distribution of individual article-and-review research outputs for 20 countries during 2010-18.