Journal Impact Factor

Journal Impact Factor

Name:  Journal Impact Factor

Can apply to: Journals selected for indexing by Journal Citation Reports

Metric definition: The Journal Impact Factor is a measure reflecting the annual average number of citations to recent articles published in that journal.

Metric calculation:  From Wikipedia: “In any given year, the impact factor of a journal is the number of citations received in that year by articles published in that journal during the two preceding years, divided by the total number of articles published in that journal during the two preceding years.”

Data sources: Thomson Reuters Journal Citation Reports

Appropriate use cases: The JIF can be useful in comparing the relative influence of journals as measured by citations. Used appropriately and in conjunction with other metrics, the JIF can be useful in collection development decisions made by librarians.

Limitations: The widespread use of the JIF has resulted in its corruption through gaming by journal editors, perverting incentives, and misuse as a measure of the quality or impact of individual scholars or articles. Here are the most commonly noted limitations of the JIF:

  • There is a lack of transparency about the database of journal articles on which the JIF is calculated. More specifically, Thomson Reuters does not provide clear, concrete guidelines for the journals and article types selected for inclusion.
  • In some disciplines, 2 years is not enough time for articles to accrue citations.
  • Coverage varies by discipline, particularly for the arts and humanities, which makes context crucial for interpreting the JIF.
  • In many fields, the correlation between JIF and citation rates for a particular article is weak.
  • There is a strong English language bias in the journals covered.
  • There is a strong American bias in the journals covered.
  • The JIF is affected by many cultural differences across disciplines (e.g., frequency of publication, typical number of citations per article, average length of article, etc.) that prevents it from being useful in comparing metrics across disciplines.
  • Interdisciplinary journals are not well represented in the JCR database.
  • Editorial policies can affect the JIF.

Inappropriate use cases:

Available metric sources: Thomson Reuters Journal Citation Reports

Transparency: The process of selecting journals and article types for inclusion in the Journal Citation Reports database is not clearly documented, though the formula for calculating the JIF is public.


Timeframe:  The JCR is typically released two years after the year in question. For example, the JIF for 2015 were released in 2017.


Posted on

July 23, 2017