Web of Science and Scopus | Search discrepancies explained

Web of Science Core Collection

Clarivate’s WoS Core Collection is an abstract and citation index covering over
21,000 peer-reviewed journals, over 134,000 books, and conference papers from
over 300,000 conferences. The WoS Core Collection covers six indices: the Science Citation Index, the Social Sciences Citation Index, the Arts & Humanities Citation Index, the Conference Proceedings Citation Index, the Book Citation Index, and the Emerging Sources Citation Index.

Scopus

Scopus is an abstract and citation database launched by Elsevier. It covers about 27,000 peer-reviewed journals, 1,167 book series, over 290,000 stand-alone books, 11.7 million conference papers from 149,000 conference events, and over 49 million patents. Since 2021, preprints are included, for a current total of over 2 million preprints. Scopus includes over 90.6 million records of which 84 million were published after 1969. It includes 2.4 cited references dating back to 1970. Unlike WoS, Scopus has a single citation index.

Content overlap

Scopus appears to focus on comprehensiveness, whereas WoS focuses on selectivity. Both databases have considerable overlap in scientific documents, especially in life sciences and to a lesser extent in social sciences and humanities. Nevertheless, both databases have unique content. Scopus, in particular, covers many publications not included in the WoS. Most journal articles covered by the WoS are also covered by Scopus. Other publication types like meeting abstracts, conference proceeding papers and book reviews are better represented in the WoS than in Scopus.

Factors that can cause discrepancies in search results

Due to differences in coverage, running similar search queries will yield different numbers of results. In addition, differences in indexing may yield different numbers of results. Both databases not only include author keywords
but also additional keywords, for example, in Keyword Plus in WoS and Indexed Keywords in Scopus. These may create differences. In short, a search query finds a certain article in one database and not in the other database, even though that article is included in both databases.

When you receive large differences in the number of results, you need to identify if there are additional reasons for this discrepancy.

Singular-Plural searching

The key to these discrepancies may be in the use of some database functionalities in your query. Both Scopus and the WoS automatically search for singular and plural. A search for ‘landscape’, for example, will also return ‘landscapes’. However, phrase searching, which is required for search terms consisting of more than one word, switches off automatic retrieval of singular and plural in the WoS, but not in Scopus. This means that searching for "energy landscape" in WoS will return only articles with energy landscape. Doing the same search in Scopus, however, will return articles with energy landscape and energy landscapes. To ensure in WoS that both singular and plural are included, you have to include both variants in your WoS query, or alternatively search for "energy landscape*", where the asterisk replaces any number of characters, including no character.

Parentheses

Another reason for a big difference in the number of results in Scopus and the WoS may be a misinterpretation of your query. In a query, you commonly use different operators to combine search terms, like AND and OR. The precedence of processing these operators is different in the WoS and Scopus. In WoS AND goes before OR, in Scopus OR goes before AND. To ensure that your query is correctly processed, you must override operator precedence by using parentheses. Similar to mathematics, the expression within the parentheses is executed first. Searching for (influenza OR flu) AND avian will execute the same search in both databases and return records containing both influenza and avian or both flu and avian. The query without parentheses will return a different number of results in both databases.

Support

The Library developed e-learning modules to help you create a systematic search in these databases. The E-learning module Search and Evaluate helps you to create a systematic search. The E-learning module Scopus shows some specific features of this database. For more support or any questions on creating searches for literature reviews or systematic reviews, please email our Information Specialists at the Servicedesk Facilities.