Measuring Research Impact: Getting Started

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.

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.

• 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.
• Available on Eigenfactor website, or via 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.

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• Elsevier/Scopus alternative to Impact Factor, Uses data from Scopus, with a 3-year citation window.  (Scopus inclusion criteria)
• CiteScore calculates the average number of citations received in a calendar year by all items published in that journal in the preceding three years. See CiteScore FAQs to learn more.
• Available via Scopus.
• Not as established as Journal Impact Factor
• Some controversy: 
  • Is CiteScore, the new Elsevier-Scopus alternative to Impact Factor, favorable to Elsevier journals?
  • “Should CiteScore ever reach the level of prominence that Impact Factor currently holds, journals will face strong incentives to reduce or eliminate the news and editorials [front matter] that appeal many readers” (Enago Academy)

• A citation metric weighted by the prestige of a journal. Subject field, quality, and reputation of the journal have a direct effect on the value of a citation.  See detailed description of SJR.
• Based on Scopus data, with a 3-year citation window.
• Attempts to normalize for differences in citation behavior between subject fields. 
• Available on SCImago Journal and Country Rank website, which provides the SJR, journal H-index and other metrics, or via Scopus.
• SCImago Journal and Country Rank website provides journal rankings. Rankings are available for some disciplines that Journal Citation Reports does not cover, such as Art & Humanities. The ranking method is based on the Google PageRank algorithm.

• SNIP uses data from Scopus, with a 3-year citation window.
• Weights citations based on the total number of citations in a given field (subject), in an attempt to facilitate "more accurate between-field comparisons of citation impact."
• Available on CWTS Journal Indicators website, or via Scopus (on Sources page and on journal title's home page).