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Understanding journal metrics: the Impact Factor

You can use metrics to help you choose which journal to submit your work to. For a long time, citation metrics were the standard (and only) tool available to evaluate journals and articles systematically.

What is a Journal Impact Factor?

An Impact Factor is one measure of the citations received by articles published in a journal. Journal Impact Factors are released annually as part of the Web of Science Journal Citation Reports®, published by Clarivate Analytics. Only journals listed in the Science Citation Index Expanded® (SCIE) and Social Sciences Citation Index® (SSCI) receive an Impact Factor.

How is a Journal Impact Factor calculated?

The Impact Factor is a very simple metric. It is the average number of citations received by articles in a journal within a timeframe. It’s calculated in the following way:

Number of citations received in 2016 to 2014 and 2015 content
Number of articles and reviews published in 2014 and 2015

What is the 5-Year Impact Factor?

The 5-Year Impact Factor is calculated using the same method as the standard Impact Factor but it attempts to reflect the longevity of some research by looking at the citation performance of articles published during the previous five years:

Number of citations received in 2016 to content published 2011 to 2015
Number of articles and reviews published 2011 to 2015

The 5-Year Impact Factor may be useful for assessing journals in subject areas where it takes longer for work to be cited.

What else do you need to consider?

Across disciplines, there are widely differing citation patterns, database coverage, and dominance of journals, all of which can be seen in the Impact Factors of individual journals. Differences in Impact Factor also exist between different kinds of journals (basic, applied, practitioner, or educational). Most Arts and Humanities journals will not receive an Impact Factor.

What other metrics are there?

A large number of other journal metrics have been created to measure citation performance, based either on the Web of Science or the Scopus databases. These include the CiteScore, Eigenfactor, SCImago Journal Rank, and SNIP.

Don’t know your Impact Factor from your h-index? Altmetric Attention Score from Eigenfactor? Get an introduction to research metrics with our handy guide.