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frequently-issued ones, and of older journals over newer ones. Particularly in the latter case, such
journals have a larger citable body of literature than smaller or younger journals. Perhaps the most
important and recent use of JIF is in the process of academic evaluation. The impact factor can be used
to provide a gross approximation of the prestige of journals in which individuals have been publishing.
This is best done in conjunction with other considerations such as peer review, productivity, and
subject specialty citation rates.

There have been many innovative applications of JIF, primarily providing librarians and researchers
with a tool for the managing library journal collections. In market research, the IF provides
quantitative evidence for editors and publishers for positioning their journals in relation to the
competition, especially others in the same subject category. JIF along with other JCR data may also
serve advertisers interested in evaluating the potential of a specific journal.

Limitations of JIF

The Impact Factor is an arithmetic mean and it doesn’t adjust for the distribution of citations. This
means that one highly-cited article can have a major positive effect on the JIF, skewing the result for
the two years. Most journals have a highly-skewed citation distribution, with a handful of highly-cited
articles and many low- or zero-cited articles.

The Impact Factor only considers the number of citations, not the nature or quality. An article may be highly
cited for many reasons, both positive and negative. A high IF only shows that the research in a given journal
is being cited. It doesn’t indicate the context or the quality of the publication citing the research.
Impact Factors cannot be compared across different subject areas. Different subject areas have different
citation patterns, which reflects in their IFs. Research in subject areas with typically higher IFs (cell
biology or general medicine, for example) is not better or worse than research in subject areas with
typically lower IFs (such as mathematics or history).

The JCR doesn’t distinguish between citations made to articles, reviews, or editorials. So that the IF doesn’t
penalize journals that publish rarely-cited content like book reviews, editorials, and news items, these
content types are not counted in the denominator of the calculation, however, citations to this kind of
content are still counted increasing the IF without any offset in the denominator of the equation.

Impact Factors can show significant variation year-on-year, especially in smaller journals. As IFs
are average values, they vary year-on-year due to random fluctuations. This change is related to
the journal size (the number of articles published per year), the smaller the journal, the larger the
expected fluctuation.

Immediacy Index, Five Year Impact Factor

To supplement the IF dynamics, Clarivate brings out two other indices, which are more relevant for
discipline-specific usage.
The Immediacy Index is the average number of times an article is cited in the year it is published,
for example, in case we are considering Immediacy Index for the year 2019, then the publications
and the citations are from 2019 only. It is similar to JIF, except the window for both the numerator
and the denominator is restricted to the JCR data year. The journal Immediacy Index indicates how
quickly articles in a journal are cited. A related idea, the Aggregate Immediacy Index indicates how
quickly articles in a subject category are cited. It is a per-article average, the Immediacy Index tends
to discount the advantage of large journals over small ones. However, frequently-issued journals may

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