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Research Impact

Tracking and Enhancing the Impact of your Research

About Journal Metrics

Journal metrics attempt to quantify the quality or influence of a given journal for purposes of comparison.  


The Journal Impact Factor, also known as Impact Factor, is the oldest and most widely used measure. Its use is often criticized for having a too-short window for analysis (two years) and failure to recognize differing expectations of citation rates among disciplines.


Important factors to consider are the time frame of the calculation and whether or not the metric includes all items in a journal (e.g. letters or news) or just the "citable" items. Measures that include all items tend to penalize journals that publish a variety of document types.


Note: The impact factor describes the journal as a whole, not individual articles.

Journal Impact Factor

Journal Impact Factor (Journal Citation Reports) = number of citations to a journal in the current Journal Citation Reports (JCR) year to items published in the previous two years, divided by the total number of scholarly items (articles and reviews) published in the journal in the previous two years.


There were two key changes in the June 2023 Update of the JCR:

  • Journal Impact Factors are provided for all journals in the Web of Science Core Collection journals including journals indexed in the Arts & Humanities Citation Index™ and Emerging Sources Citation Index™. 
  • Journal Impact Factors are calculated to one decimal instead of three decimals


A journal may advertise its impact factor on its website. This claim should be verified in JCR.


The JCR also offers a five-year impact factor calculation and a variety of other metrics, including Journal Citation Indicator, Immediacy Index, Cited and Citing Half-Life, and Article Influence Score.


CiteScore (Scopus) = citations to a journal in a given year to documents in that journal from the previous three years, divided by the total number of documents (not just scholarly documents) published in the journal in the previous three years.

Google Scholar Journal Metrics

h5-index (Google Scholar Metrics)h5-index is the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2011-2015 have at least h citations each.  So, a publication that had 5 articles but only three had at least 5 citations or more would have an h5 of 3.


h5-median (Google Scholar Metrics)h5-median for a publication is the median number of citations for the articles that make up its h5-index.


Google Scholar Metrics provides rankings of English-language journals by subject areas and top 100 overall rankings for journals in English and several other languages.

See also: Coverage of Publications


SCImago Journal Rank

SCImago Journal Rank (SJR) = the average number of weighted citations received in the selected year by the documents published in the journal in the previous three years.  


Citations are weighted based on the importance of the journal determined by a method similar to Google's PageRank algorithm.


The SJR is calculated from the Scopus database 


Source: Scopus or SCImago


Subject Area Journal Rankings are also available.

Source Normalized Impact per Paper (SNIP)

Source Normalized Impact per Paper (SNIP) = number of citations in the present year to publications in the past three years, normalized to correct for differences between scientific fields.


SNIP is calculated by the Leiden University Centre for Science and Technology Studies (CWTS) and based on the journals in the Scopus database. where they are accompanied by stability intervals that show the tendency of the indicator to fluctuate over time.


Although SNIP values are given for arts & humanities journals, they tend to be artificially low because of the way the indicator is calculated. Rankings within disciplines are available.


Source: Scopus and CWTS

Eigenfactor Score

Eigenfactor Score = a measure of a journal's total importance to the scientific community using a specific year's citations to articles in the previous five years.

Eigenfactor (see link at right) uses the source journals in Journal Citation Reports and an algorithm based on network theory and similar to Google's PageRank.  In general, journals that publish more articles have higher scores.  Eigenfactor also produces the Normalized Eigenfactor Score, scaled so the average journal has a score of 1 and the Article Influence Score.  The Eigenfactor score is also listed in Journal Citation Reports.

Eigenfactor scores are detailed at and

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