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Scholarly Impact Metrics

Journal Impact - what is it, how is it calculated

 

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.

Sources for Journal Impact

 

SCImago Journal Rank (SJR): A prestige metric that can be applied to journals, book series and conference proceedings. With SJR, the subject field, quality and reputation of the journal have a direct effect on the value of a citation. 

SJR accounts for both the number of citations received by a title and the importance or prestige of the titles where such citations come from. It is a variant of the eigenvector centrality measure used in network theory. Such measures establish the importance of a node in a network based on the principle that connections to high-scoring nodes contribute more to the score of the node. The SJR indicator, which is inspired by the PageRank algorithm, was developed for extremely large and heterogeneous journal citation networks. It is a size-independent indicator and ranks journals by their 'average prestige per article'.

Calculation:

average # of weighted citations received in a year
# of documents published in previous 3 years

Developed by: Professors Félix de Moya, Research Professor at Consejo Superior de Investigaciones Científicas and Vicente Guerrero Bote at University of Extremadura.

 

Scopus - CiteScore

New Scopus metric: CiteScore

December 2016 saw the launch of a new Scopus metric, CiteScore, along with associated other metrics. The new journal-level metrics will provide an additional view of journal performance and have been published for over 22,000 journals index in Scopus. This post will give you an overview of the metric and what it could mean for your journal.

What is it?

CiteScore is calculated from all citations recorded in Scopus in one year to content published in the last three years, divided by the number of items published. Unlike pre-existing metrics, such as SNIP and SJR, the CiteScore has been produced directly by Scopus and is easily replicable via the Scopus database. In addition to CiteScore Scopus are also publishing additional rankings, such as the CiteScore percentile based on subject categories and a monthly CiteScore tracker. The already established SNIP (Source Normalized Impact per Paper) and SJR (SCImago Journal Rank) will continue to be published.

There are three key differences to the Journal Impact Factor:

It is based on the Scopus database rather than Web of Science, therefore the number of citations in certain subject areas will be notably higher.

It takes into account a three-year citation window rather than two.

The dominator includes all content published in the journal, not just articles and reviews.

How can I find my CiteScore?

All the Scopus metrics can be freely accessed at www.scopus/sources . This includes the CiteScore, SNIP and SJR along with the percentile rankings and CiteScore Tracker.

What does it mean for my journal?

For journals that are indexed in Scopus, CiteScore will provide a simple metric that is easily recreated within the Scopus system.

For all Scopus indexed journals, the CiteScore will provide an additional way to benchmark citations against a much wider set of journals.

For journals that already have Impact Factors these advantages will be most notable in the Arts & Humanities where Clarivate Analytics does not publish Journal Impact Factors and the wider Social Sciences where the broader coverage in Scopus will have a larger effect.

Due to the nature of the calculation, journals that publish a large amount of front matter (editorials, peer commentaries, etc.) will perform worse by CiteScore than by Journal Impact Factor.

Things to consider

Citation counts have a large variance between subject areas, therefore we would always strongly encourage you to evaluate your journal’s performance using its subject quartile or percentile. (Thus you will be comparing journals with similar subject citation profiles.)

If you think your journal is not listed in the most appropriate subject areas, please contact your T&F Managing Editor.