Journal Impact Measures

Some journals are read and cited more than others. Measuring the impact of a journal may help authors identify where to publish as well as how much visibility their research may expect in return. It is important to note that journal impact measures vary among research disciplines due to differing citation behavior and thus cannot be directly compared.

On this page:

Journal Impact Factor

A journal’s Impact Factor averages the number of recent citations to the journal by the number of articles it recently published. The 2009 Impact Factor is calculated by taking the number of citations made in 2009 to articles published in the journal in 2007 and 2008, and dividing by the total number of that journal's 2007 and 2008 articles. Therefore the Impact Factor of a journal only considers a brief period and can change from year to year. Impact Factor can be viewed in either of ISI’s two data sources:

  • Find a journal’s Impact Factor: use Web of Knowledge to search by journal title. In an article record, click “View the journal's Impact Factor (in Journal Citation Reports)” in the right-hand box under Additional Information.
  • Compare journals in a subject discipline: use Journal Citation Reports to view a journal’s Impact Factor with others in its discipline. Learn more about using Journal Citation Reports by watching this video tutorial.

SCImago Journal Rank (SJR)

The SJR is a free website based on the citation data tracked in Elsevier’s Scopus database. The ranking system works like the Google PageRank algorithm as it incorporates citation data as well as relationships among journals (via citations).

Eigenfactor Score

A journal’s Eigenfactor Score counts the citations made to a journal over time, but gives more weight to the citations from highly ranked journals than weaker ones, another use of PageRank theory. Therefore Eigenfactor ranks the overall impact of a journal, and not the impact of articles within that journal.

  • reports a journal’s Eigenfactor Score, a measure comparable to a journal’s Impact Factor, and Article Influence.
  • ISI Journal Citation Reports also lists Eigenfactor Score and Article Influence.

Journal h-index

SCImago Journal Rank calculates a journal’s h-index, or the number of articles in a journal (h) that have received at least h citations.

Further Reading

"Why the Impact Factor of Journals Should not be Used for Evaluating Research" by P. O. Seglen (1997) in the British Medical Journal.

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