Research Impact

Journal metrics measure the citation rate of a particular journal based on the number of articles published in that journal and the number of citations the journal receives.  Like other impact measures it has its limitations and must be considered as one of several factors in evaluating a journal.

The Journal Impact Factor (JIF) is calculated by dividing the number of citations received by the articles of a journal by the total number of articles published in the journal during the two previous calendar years.

Journal Impact Factors can be found in Journal Citation Reports, a subscription-based resource that is available through Western Libraries.

Limitations of Journal Impact Factor:

• Only calculates citations for publications that are indexed by Web of Science.
• Can only be used to evaluate journals within disciplines, not between them.
• Excludes journals covered by the Arts & Humanities Citation Index because their citation patterns are different.
• Most journals are in English and from the developed world, although the Emerging Sources Citation Index is an effort to address that.
• Can be strongly influenced by outlier articles.
• Review articles tend to raise impact factor.

Eigenfactor measures journal impact based on the number of times journal articles have been cited and which journals they were cited by. Citations from journals with high impact factors will have a greater influence on the score than lesser cited journals. Eigenfactor removes metrics from journal self-citation, making it more difficult for journals to artificially increase their score.

Eigenfactor is calculated in a similar manner to Journal Impact Factor but with higher impact journals being given more weight. A thorough explanation of the calculation method is provided by Eigenfactor.

Limitations of Eigenfactor:

• Only available for Journal Citation Reports from 2007 and later
• Journals are assigned to one category, even if they are interdisciplinary
• Difficult to compare journals across disciplines
• The results can be complex to interpret

This metric, devised by Elsevier, is similar to the Journal Impact Factor. The primary difference is that all published material in a journal (including editorials, letters and news items) are counted in the calculation.

Calculating a CiteStore

The CiteScore is calculated by dividing the number of all documents published in a journal during the preceding 3 years (A) by the citations to those documents (B) .

Limitations:

• Inclusion of content such as letters and editorials can dilute the results.
• Only journals included in Scopus will have a CiteScore.

SCImago uses indicators developed by Scopus from 1996 to the present day. It contains indicators such as journal ranking, h-index, and total citations. This is one of the few tools to measure research impact in the arts and humanities. SCImago indexes articles published in more countries and in more languages than most other metric tools.

Limitations of SCImago:

• Does not address the bias created by review journals
• Citations from lower prestige journals get little credit
• Ranks are based on the total number of articles in a journal, not the total number of citable articles
• The complex calculations used to create a score are proprietary and cannot be independently verified

When choosing which journal to publish in there are several other important factors to consider beyond traditional research impact measures. See our Deciding Where to Publish page for more considerations.