A journal's Impact Factor is a measure of the frequency with which the "average article" in a journal has been cited in a given period of time.
The JIF is simple and easy to calculate – all you need to know is the number of scholarly works that a journal published in the last two years (also referred to as citable items) and how many citations they received from papers published in the JCR data year. Various factors influence how many citations could be accumulated including the typical number of references made in a paper, the age of papers referenced, the total number of papers published and even the meaning of a citation itself. Due to these differences, comparisons for the JIF should be made in category or between adjacent fields.
Suggestions for finding Impact Factors of particular journals:
Look at the webpage of journal publishers, e.g. Elsevier - Tetrahedron Letters, as Impact Factors are sometimes indicated on the journals’ homepages.
Each year, millions of scholarly works are published containing tens of millions of citations. Each citation is a meaningful connection created by the research community in the process of describing their research. The journals they use are the journals they value. The Journal Citation Reports (JCR) aggregates citations to our selected core of journals, allowing this vast network of scholarship to tell its story.
Source: Clarivate Analytics
What are Journal Citation Reports (JCR)?
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"The Journal Citation Indicator (JCI) is a new way to measure the citation impact of a journal’s recent publications using a field-normalized calculation. This new approach provides a single value that is easy to interpret and compare, complementing current journal metrics and further supporting responsible use. Starting from the 2021 JCR release, it will be calculated for all journals in the Web of Science Core Collection".
In the last 20 years, the bibliometric community has devoted much attention to the issues of interpretation and comparison, devising more sophisticated ways to measure citation impact than by counting the number of citations. Among these, normalization has become the de facto standard – rather than using a citation count as a measure of impact, the citations received by a paper are compared against a cohort of similar papers and expressed as a ratio or percentile. The JCI is a normalized indicator which means that it accounts for variation and provides a number that can be more easily compared across disciplines. The calculated value represents the average category-normalized citation impact for papers published in the prior three-year period.
The normalization steps make it more reasonable to compare journals across disciplines, but careful judgement is still required. Adjacent fields (e.g. those in the physical sciences) can be more readily compared since the bibliometric characteristics of scholarly publication are similar, and the value of a citation is more comparable. However, in the arts and humanities, citations provide a weaker signal of academic impact, and other qualitative measures should also be considered. Comparing journals in the arts and humanities to those in the sciences or social sciences based solely on their Journal Citation Indicator would be ill advised.
When compared to the Journal Impact Factor, most indicator values that are based on citations will be correlated – both the Journal Citation Indicator and the JIF are most affected by citations to citable items. However, differences between Journal Citation Indicator and JIF will occur for the following reasons:
• The time period of articles and reviews is slightly different, with the Journal Citation Indicator considering an additional year of content.
• The JIF calculation is based on citations made in the current year, whereas the Journal Citation Indicator sums citations across the whole time period following publication, up to the end of the current year.
• The JIF calculation includes unlinked citations – those that could only be attributed to a journal, but not linked to a specific item. Since CNCI is an article-level metric, unlinked citations are not counted in the Journal Citation Indicator.
• The JIF calculation counts all citations made to any item published in the journal (the numerator) and is not limited to only the citable items. The Journal Citation Indicator only counts citations made to the citable items – any citations to noncitable items (e.g. letters, news, editorials) are ignored.
Use CiteScore metrics to: