Web of Science (WoS) is a subscription-based multidisciplinary citation database. It was originally created by the Institute for Scientific Information (ISI) and it is currently maintained by Clarivate Analytics. The WoS platform consists of several, separate multidisciplinary, field-specific and regional citation databases as well as patent and research information databases. All in all, the WoS databases hold 182 million records starting from the 19th century. A set of multidisciplinary journals, books and conference publications, selected as globally the most influential, form the Web of Science Core Collection database. The Core Collection databases are also utilised as the base data of Clarivate Analytics’ InCites analysis tool and the Journal Citation Reports tool. This guide focuses in particular on the Web of Science Core Collection databases.
Figure 1. The Web of Science database comprises several multidisciplinary, field-specific and regional databases. © Clarivate, 2021. 24 November 2021.
Database content and quality assurance
WoS Core Collection comprises six separate databases (Figure 1), which include, in total, nearly 22,000 globally published high-quality scientific journals, more than 226,000 conference publications, and more than 126,000 editorially chosen books on the fields of natural sciences, social sciences, humanities, technology and arts (data from 2022). Clarivate sells separate licences for each database as well as separate retroactive data packages for some of them. Temporal coverage is the highest for the materials of social and natural sciences; it is possible to license these materials starting from the early 20th century. The materials of arts and humanities start from 1975, conference publications from the 1990s, and monographs have been indexed since 2005. The client organisation may choose which citation databases and what kinds of a temporal coverage it wishes to include in its subscription. This should also be taken into account when carrying out bibliometric analyses. The number of publications listed in the search results depends on the licences used. However, the number of citations received by an article remains the same regardless of the extent of the subscription. In Finland, the FinElib consortium offers access to the key Core Collection indexes: Science Citation Index Expanded, Social Sciences Citation Index, Arts and Humanities Citation Index and Emerging Sources Citation Index. The materials requiring a separate subscription, i.e. Conference Proceedings Citation Index and Book Citation Index, are not covered by the FinElib licences.
Coverage across different fields of science
Several studies show that the coverage of the WoS Core Collection database is lower within many fields of sciences than that of its competing databases (e.g. Mongeon, P. & Paul-Hus, A. 2016; Martín-Martín, A. et al. 2021; Singh, V.K. et al. 2021; Visser, M. et al. 2021). The publishing practices of different disciplines, such as the publication type and language, are reflected in the coverage. The WoS Core Collection mainly comprises journals, and fields of science, where books are a typical publication type, are poorly represented in the databases, in particular. WoS Core Collection mainly features materials in English, which means that the fields of science that commonly produce publications in other languages are less well represented in the database. The lowest coverage is in the fields of social sciences and humanities, where the coverage can remain as low as ten per cent. Biosciences and medical sciences, as well as some fields of natural science and technology, have the best coverage. The introductory section of this chapter has more information on the coverage differences between the citation databases.
Collection policy
The different citation databases have different collection policy strategies. WoS’s content is selected by an internal editorial board. Each member of the editorial board focuses on the materials of a certain topic, and the editors are unbiased agents without any affiliation with publishing houses or research institutions. WoS emphasises a selective collection policy, which partly explains its weaker coverage compared with other citation databases. A scientific journal, for example, must meet 24 quality criteria in total to be indexed in the database as well as four impact criteria that are based on citation data. Among other criteria, the journals must have a peer review process, an editorial board and an ISSN identifier, and the title and abstract of an article must be written in English. The purpose of the impact criteria is to identify and select the most influential journals of the specific field of science. The journals meeting all the quality criteria are approved for the Emerging Sources Citation Index (ESCI) collection. The journals that also meet the four impact criteria are approved for the Science Citation Index Expanded (SCIE), Social Sciences Citation Index (SSCI) or Arts & Humanities Citation Index (AHCI) collections, depending on the field of science of the journal.
Publication types
The Core Collection databases comprise, in total, nearly 22,000 globally published high-quality scientific journals (including Open Access journals), more than 226,000 conference publications, and more than 126,000 editorially chosen books on the fields of natural sciences, social sciences, humanities, technology and arts (data from 2022). The Core Collection also holds small amounts of other types of publications, such as editorial materials, documents describing the research data and reviews of artistic works. Visit the website of the service to view the entire catalogue of publication types available in the database.
In addition to the Core Collection databases, the Web of Science product family features services such as a separate patent database Derwent Innovations Index (DII) and the Data Citation Index, which includes research data materials.
Database updates
Since March 2021, the WoS Core Collection databases have been updated daily. In December 2017, the weekly updates were first changed to updates from Monday to Friday, and now the database is updated daily. The update frequency of content of other databases than those in the Core Collection varies from weekly to monthly updates. However, it should be considered that it takes an average of four to eight weeks from the moment of publishing for a publication to be indexed in the database. Sometimes, indexing can also take considerably longer.
Classification of fields of science
Classification of fields of science is a key perspective when reviewing the citations received by publications. The number of citations accumulated by an individual publication is a relatively insignificant number. However, comparing the number of citations with that of other publications in the same field allows us to see whether the number is higher or lower than the average and by how much. The database should be able to determine the classification of fields of science of the publications and the publication channels as accurately and exactly as possible in order to ensure the comparability of the number of citations, making the use of indicators created on the basis of the citation information well-founded.
Every journal, conference publication and book in the Core Collection databases has been classified to one or more subject categories of a field of science (Web of Science Subject Categories). Each individual record holds information about the subject category of its source publication. There are about 250 subject categories in total within natural and social sciences, arts and humanities. The extensive fields of sciences, such as physics, have been further classified into more specific subcategories, such as ‘Physics, applied’ and ‘Physics, nuclear’.
This more accurate classification is important, as citation practices can vary widely between different fields of science. However, as an individual journal, book or conference publication cannot usually be linked to just one individual category, the categories have some overlapping elements, which can make the analysis more challenging. Each publication inherits all the subject categories assigned to its parent publication. The publications of multidisciplinary journals, such as Nature and Science, are reclassified into as exact a category as possible. Multidisciplinary journals publish articles about several topics, but the individual articles usually focus on just one subject. Utilising the citation information on such articles with algorithmic methods often makes it possible to determine a suitable subject category for the article. However, if a suitable category is not identified, the subject category of the article will remain multidisciplinary. A list of the field of science classifications applied by WoS and information about the subject categories determined for individual journals are available on the website of the service.
Basic functionalities of the database
Search options
In the WoS user interface, you start the search by first selecting the desired databases. You can use the same user interface to search all databases of the WoS product family. The Core Collection databases are most commonly used for publication metrics. Each record indexed in a Core Collection database includes the bibliographic information on the publication as well as information on all the authors of the article with their affiliations included, the abstract of the publication and its keywords (if included by the author), information about the funders of the publication and the grant numbers (if included) as well as data on all the articles citing the publication. The Core Collection databases also comprise the base data of the Clarivate Analytics’ InCites analysis tool and the Journal Citation Reports tool.
You can start your search by searching for documents, authors, or documents citing a specific publication (cited references). You can either use the basic search or an advanced search function. The advanced search allows the user to search for publications based on 35 different details, such as the title, DOI, author, researcher ID, subject, keywords of the publication reported by the author, grant number, funder and certain affiliations. The search fields can be combined with the help of Boolean operators (AND, OR, NOT), and completed searches can also be further combined. The search results can be filtered by the year of publication, publication type, WoS research area or the author’s affiliation, for example. The author search is still in its beta phase, but the function allows users to search for publications written by a certain person. The WoS algorithms aim to recognise publications belonging to a certain person by taking into account not only their name but also their affiliation information, publication history, the subject area of their publications, and other authors of their publications, as well as by utilising the researcher IDs maintained by the authors and the publications linked to these. The function strives to improve the accuracy of the author search and author profiles by offering all registered users of the database the chance to rectify data — as opposed to just the authors themselves. Searching by cited references will bring up all documents citing a certain publication, including those that have not been indexed in the WoS databases.
Web of Science analysis tools
The search results from a WoS database can be analysed with the help of two different analysis functions: Analyze Results and Citation Report.
The Analyze Results function is facilitated by the wide range of indexed fields in WoS. You can find out, for example, which countries, organizations or researchers appear most often in the search result set. The results can be grouped based on scientific fields of journals, publication types or research funders. The service offers a few different visualisation views to use, or the results can be downloaded for further processing in other software.
The Citation Report function brings together the citation statistics of the search result. The report includes the following information:
- the total number of publications found
- the total number of citations to the publications found
- the total number of citations to the publications found, with self-citations excluded (citations that come from other publications in the set of publications under analysis)
- the total number of citing articles
- the total number of citing articles, with self-citations excluded (citing articles included in the analysed result set were removed)
- the average number of citations per publication
- the h-index of the publications included in the search result.
Note that the citation statistics only include citations from publications indexed in the databases used in the search. If you want to search the citation information more extensively, using the WoS Cited References search function is recommended.
Figure 2. View of a WoS citation report. © Clarivate Analytics, 2022.
Web of Science researcher profile ResearcherID
Researcher IDs help solve problems related to identifying the authors of publications, such as common surnames, name changes and characters not used in the English language. The purpose of the Web of Science’s ResearcherID is to connect a researcher to the correct publications in the Clarivate Analytics product family’s services: Web of Science and InCites. The basis of the ResearcherID service are the profiles created and maintained by the researchers themselves. Every researcher can create a profile for themselves in the service. The ResearcherID number will remain the same even if the researcher’s name or affiliation information changes.
You can also read more about the use of researcher identifiers in the Authorship chapter of this guide.
Web of Science organisation profiles
In addition to the researcher profiles, the WoS Core Collection databases allow for organisation-specific profiles to be maintained. Similarly to researchers, the names of organisations may change or the organisations may undergo structural changes. In the university sector in Finland, for example, Aalto University was formed by combining the Helsinki School of Economics; The University of Art and Design Helsinki and Helsinki University of Technology, and the University of Eastern Finland was founded by combining the universities of Kuopio and Joensuu. The Core Collection databases feature Organization-Enhanced profiles, which are usually kept up to date by the specialists of the scientific libraries of organisations. Keeping the organisation profiles of citation databases up to date is an important task, as this information is used for various benchmarking and collaboration analyses. Many ranking organisations also utilise this data. The organisation profiles of the InCites analysis tool based on the WoS Core Collection data have been created directly based on the Organization-Enhanced profiles.
Limitations and criticism
The key limitation of WoS is its accessibility, as using the database requires a paid licence. Universities have typically acquired the licence but many research institutes and universities of applied sciences may not have one. The access of Finnish organisations to WoS can be checked on the Web of Science subscribers website of the FinElib consortium (only in Finnish).
Another key limitation is the coverage of content indexed by WoS. The selective collection policy of WoS means that it clearly has lower coverage than many other databases in several fields of science, especially in social sciences and humanities.
The WoS database also has some technical limitations that make the further processing of large result sets more challenging, in particular. The WoS database allows for 1,000 records at most to be saved into other systems at one time. An exception to this is the InCites service, which allows users to transfer a dataset of up to 50,000 records. However, it is possible to save larger result sets in several batches (1–1,000, 1,001–2,000, 2,001–3,000, etc.).
Other options for using WoS data
Clarivate has productised the WoS data also for several separate — and separately paid for — machine-readable interfaces. The WoS access subscribed to by several Finnish organisations through the FinElib consortium only includes the most basic WoS API Lite and Links AMR interfaces. WoS API Expanded, which includes more extensive metadata on the publications, as well as citation numbers, for example, and the WoS Journals API, which include Journal Impact Factor metrics, both require additional subscriptions.
Sources
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Clarivate Analytics. (2022) Web of Science Core Collection Help. Available: http://images.webofknowledge.com/WOKRS535R111/help/WOS/index.html [Accessed 4.2.2022]
Clarivate Analytics. (2022) Web of Science LibGuides. Available: https://clarivate.libguides.com/home [Accessed 4.2.2022]
Clarivate Analytics. (2022) Näkymä WoS viittausraportista [screenshot]. Available: https://www.webofscience.com/wos/ [Accessed 4.2.2022]
Leino, Y. (2020) Web of Science julkaisujen osuus VIRTA-julkaisuista päätieteenaloittain vuosina 2012-2017 [figure]. Esityksessä Julkaisutietokantojen kattavuus: VIRTA vs. Web of Science, Bibliometriikkaseminaari 2020. Available: https://wiki.eduuni.fi/display/CSCbibliometriikka/Bibliometriikkaseminaari+2020 [Accessed 4.2.2022]
Martín-Martín, A., Thelwall, M., Orduna-Malea, E. and López-Cózar, E.D. (2021) Google Scholar, Microsoft Academic, Scopus, Dimensions, Web of Science, and OpenCitations’ COCI: a multidisciplinary comparison of coverage via citations. Scientometrics, 126, pp. 871–906. Available: https://doi.org/10.1007/s11192-020-03690-4
Mongeon, P. and Paul-Hus, A. (2016) The journal coverage of Web of Science and Scopus: a comparative analysis. Scientometrics, 106, pp. 213–228. Available: https://doi.org/10.1007/s11192-015-1765-5
Singh, V.K., Singh, P., Karmakar, M. et al. (2021) The journal coverage of Web of Science, Scopus and Dimensions: A comparative analysis. Scientometrics, 126, pp. 5113–5142. Available: https://doi.org/10.1007/s11192-021-03948-5
Visser, M., van Eck, N.J. and Waltman, L. (2021) Large-scale comparison of bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic. Quantitative Science Studies, 2(1), pp. 20–41. Available: https://doi.org/10.1162/qss_a_00112