Measures of Journal Impact
Journal impact metrics attempt to quantify the importance of a particular journal in its field, usually via a formula that takes into account the number of articles published per year and the number of citations to articles published in that journal. On this page, you will find descriptions of common journal impact metrics, as well as tools to use to find them.
Journal Impact Factor
The Journal Impact Factor is a ratio devised as a measurement of the average citedness of a journal. It is calculated by dividing the number of citations to a particular publication in a certain year by the number of citable articles published in the journal in the previous two years. Other related measurements may also be calculated, such as the Five-year impact factor (which looks at the previous 5 years), or the Immediacy index (which is the average number of times an article is cited in the year it is published).
Journal Impact Factors are not a measure of the citedness of any particular article in a journal, but rather of the journal as a whole. They also can be influenced by other considerations. For example, a journal that publishes mainly review articles may have a higher impact factor as these are more often cited.
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Journal Citation ReportsJournal impact factors covering both the sciences and social sciences, but not the humanities (though History is included in social sciences). It is updated annually.
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Web of Science: Journal Citation ReportsJournal Citation Reports is sourced from Web of Science Core Collection and captures cited references for all content in Clarivate published journals.
Eigenfactor and Article Influence Scores
Eigenfactor: Measurement of the 'importance' or 'influence' of a journal. Citations from prominent journals are weighted more than citations from lesser known journals.- Article Influence: Calculated by dividing the Eigenfactor by the number of articles published in the journal.
- Both scores use a 5-year citation window and use data from Journal Citation Reports.
- The sum of the Eigenfactor scores of all journal listed in Journal Citation Reports (JCR) is 100. If a journal has an Eigenfactor score of 1.0, it has 1% of the total influence of all indexed publications.
- Access the EigenFactor:
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EigenFactor Journal RankingReports a journal’s Eigenfactor Score, a measure comparable to a journal’s Impact Factor, and Article Influence.
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Journal Citation ReportsEigenfactor is part of the additional metrics listed at the bottom of a Journal's Profile.
CiteScore
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ScopusCiteScore and CiteScore Rank and Trend are part of journal profiles.
A journal's CiteScore is the total number of citations in a year to articles published in the three previous years, divided by the total number of articles published in those three years.
CiteScore is limited to only scholarly articles, conference papers and review articles and does not consider citations from trade publications, newspapers, or books.
CiteScore is similar to the Impact Factor but uses Scopus to gather its data and three years rather than two as the publication period. -
Scopus Inclusion CriteriaMore information on how Scopus CiteScore is calculated
- CiteScore Criticism:
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CiteScore: Accessible Analytics or Misleading Metrics?Published by Enago Academy, November 2023
SJR (SCImago Journal Rank)
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Scimago Journal and Country RankA free website, based on materials within Scopus.
The rankings seek to measure the prestige of a journal while accounting for both the number of citations recieved by the journal and the prestige of the journals from which the citations come. Full documentation is available on their website.
SNIP (Source Normalized Impact per Paper)
Source Normalized Impact per Paper (SNIP) measures the average citation impact of the publications of a journal. It seeks to correct for differences in citation practices between scientific fields, thereby allowing for more accurate between-field comparisons of citation impact.
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CWTS Journal IndicatiorsCWTS Journal Indicators provides free access to bibliometric indicators on scientific journals. The indicators have been calculated by Leiden University’s Centre for Science and Technology Studies (CWTS) based on the Scopus bibliographic database produced by Elsevier. Indicators are available for over 20,000 journals indexed in the Scopus database.