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Jefferson

Journal Evaluation & Measuring Author Impact

Journal Impact Factor

The oldest and most well-known of the journal metrics, the JIF is a citation count based measure that was originally developed as a way to help academics and librarians compare the quality of a particular journal to others in its field.

  • The impact factor determines an average citation rate for articles in a particular journal. It is a ratio that is calculated by dividing the number of citations to a journal with the number of published articles that could have been cited from that journal. Two years of data are used in calculations.
    • Impact Factor = total # of citations / total number of citable articles
  • Citable articles do not include editorial content, such as letters and commentary articles.
  • It can not effectively compare journals across disciplines, as citation patterns across different disciplines can vary widely.
  • It is a proprietary metric that uses data from Clarivate Analytic's Web of Science database, and it requires a paid subscription to access.
  • While it works best for disciplines where articles develop citation counts rapidly, a JIF that is calculated using 5 years of data is also available.

Criticisms have been made against the JIF over the years, such as the fact that the metric can be manipulated by journal editors who can, among other tactics, encourage authors to cite other articles published in their journal (self-citations). However, perhaps the most problematic aspect of the JIF is the way that it is often used to assess individuals for funding and promotion considerations, a use for which it was not designed. JIF does not accurately reflect the impact of each individual article in a journal. A highly cited publication can boost the impact factor of a journal, benefiting an article that was published in that journal which was not cited widely, or at all.

Other journal-level metrics have since been developed (see below) which have attempted in various ways to compensate for some of the weaknesses of the JIF.

Find the Impact Factor of a journal using the Journal Citation Reports Database

CiteScore (CS)

  • ratio that uses the number of articles published in a journal over the past three years and the number of citations to those articles from the past year. 
    • CiteScore= Citation Count from 2019/Total Documents Published from 2016-2019
  • Like the JIF, it can not be used to compare journals across disciplines.
  • It uses data from a proprietary source, Elsevier's Scopus Article database. However, unlike the JIR, this metric is free to access.
  • CiteScore also recently made some improvements to the way its data is calculated in response to earlier criticisms of its methodology.

Find the CiteScore of a journal using the Scopus database.

Eigenfactor/Article Influence Score (AIS)

  • The Eigenfactor metric uses citation data to measure the influence of a journal in the scientific community.
  • It is based on the total number of citations to a given journal over the past 5 years.
  • It eliminates the possible manipulation of data by not counting self-citations.
  • Citations from higher-quality journals are weighted more than lesser-known journals.
  • This metric also adjusts for citation differences across disciplines, so that journals from different disciplines can be compared.
  • One limitation of the metric is that it gives higher scores to larger journals with a broader subject area that publish many issues. Smaller journals, that publish less often or on more narrow topics, will have lower scores by default.

Find the Eigenfactor at eigenfactor.org or through the Journal Citation Reports Database

Published with the Eigenfactor is another metric, called the Article Influence Score (AIS). This metric uses the Eigenfactor, and divides that number by the number of articles published in a particular journal, in order to obtain a measure of how influential the articles in that journal are. The mean Article Influence Score is 1.00. A score greater than 1.00 indicates that articles in the journal have an above-average influence. A score of less than 1.00 indicates that articles in that journal have a below-average influence.

Source Normalized Impact per Paper (SNIP)

  • This metric is designed to help compare the influence of journals across different academic disciplines since articles from some disciplines tend to cite sources more than others.
  • It is a ratio of a journal's average citation count to the potential citation count of its field. 
  • This measure ensures that the value of a single citation in a discipline which cites less than others will be increased.
  • It attempts to normalize for different fields at the publication level (source) rather than collecting journals into a set discipline, as more general types of field normalization do.

Find the SNIP of a journal using the Scopus database.

SCImago Journal Ranks (SJR)

  • Measures both the number of citations received by a journal and the quality of the journals that the citations come from. 
  • By giving more weight to citations from quality journals, it measures the prestige that a journal has in its discipline. 
  • Its methods work to reduces the manipulation of citations
  • It also normalizes for differences in citation behavior between subject fields, meaning that journals can be compared across disciplines.

Find the SJR of a journal using the Scopus database, or at https://www.scimagojr.com/