As a lecturer, student, researcher or research assistant in mass communication, media, and the entire social sciences, you might have come across the term “impact factor” while carrying out studies, making citations or looking for the best journals to publish your work. You may be wondering what that term means and how to know impact factor of specific journals. This article is for you.
What is Impact Factor?
Impact Factor (IF) is used to measure the importance of a journal by calculating the number of times selected articles are cited within the last few years. The higher the impact factor, the more highly ranked the journal. This is one of the major tools used to compare journals in a subject category.
According to Garfield (1972), the impact factor is useful in clarifying the significance of absolute (or total) citation frequencies. It eliminates some of the bias of such counts which favor large journals over small ones, or frequently issued journals over less 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. All things being equal, the larger the number of previously published articles, the more often a journal will be cited.
“High-impact journals” are those considered to be highly influential in their fields. A journal’s impact factor is a measure of the frequency with which an average article in that journal has been cited in a particular year.
To have a detailed understanding of what a good impact factor is, see the example below showing the 2017 Journal Citation Reports presentation of journal rankings for that year, as posted in mdanderson.libanswers.com.
During 2017, the Journal Citation Reports (JCR) database tracked all impact factors for 12,298 journals. The table below shows the number and percentage of journals that were assigned impact factors ranging from 0 to 10+. Of 12,298 journals, only 239 titles, or 1.9% of the journals tracked by JCR, have a 2017 impact factor of 10 or higher. The top 5% of journals have impact factors approximately equal to or greater than 6 (610 journals or 4.9% of the journals tracked by JCR). Approximately two-thirds of the journals tracked by JCR have a 2017 impact factor equal to or greater than 1.
|Impact Factor||Number of Journals||Ranking (Top % of Journals)|
To breakdown the meaning furthermore, what does it mean when someone says a specific journal has an impact factor of 1.0 or 2.5? An Impact Factor of 1.0 means that, on average, the articles published by a specific journal in the past one or two years have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two years ago have been cited two and a half times.
About Clarivate Analytics (the organization that provides Impact Factor of Journals)
Clarivate Analytics is the organization that provides impact factor analysis and write the Journal Citation Report. So what is their history and how do they undertake this task? Here’s a quick fact posted on Clarivate.com.
Librarians and information scientists have been evaluating journals for at least 75 years. Gross and Gross conducted a classic study of citation patterns in the ’20s (Gross & Gross, 1927). Others, including Estelle Brodman with her studies in the ’40s of physiology journals and subsequent reviews of the process, followed this lead (Brodman, 1944). However, the advent of the Clarivate Analytics citation indexes made it possible to do computer-compiled statistical reports not only on the output of journals but also in terms of citation frequency. And in the ’60s we invented the journal “impact factor.” After using journal statistical data in-house to compile the Science Citation Index (SCI) for many years, Clarivate Analytics began to publish Journal Citation Reports (JCR)(SCI Journal Citation Report, 1993) in 1975 as part of the SCI and the Social Sciences Citation Index (SSCI).
Informed and careful use of these impact data is essential. Users may be tempted to jump to ill-formed conclusions based on impact factor statistics unless several caveats are considered.
The JCR provides quantitative tools for ranking, evaluating, categorizing, and comparing journals. The impact factor is one of these; it is a measure of the frequency with which the “average article” in a journal has been cited in a particular year or period. The annual JCR impact factor is a ratio between citations and recent citable items published.
Where Can You Find the Impact Factor of a Journal?
This is always a key question for most researchers. First step is to visit the online platform of the journal you desire to know its impact factor. Under Current Year, you will see the current “impact factor”. To view the Categories and Rank, click on All years: Scroll past the Key Indicators table and click on Rank from the lower left menu: A table called “JCR Impact Factor” will appear, with the Rank for each Category the journal is in. The Journal Citation Report (JCR) provides a ranking of impact factor of journals.
How to calculate Impact Factor
You can calculate impact factor for a specific number of years you choose. For instance, a 5-year journal Impact Factor is the average number of times articles from the journal published in the past five years have been cited in the JCR year. It is calculated by dividing the number of citations in the JCR year by the total number of articles published in the five previous years.
A two-year impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years (see table below).
One important fact to note is that though Impact Factors are useful, they should not be the only consideration when judging quality. As MD Anderson observes, not all journals are tracked in the JCR database and, as a result, do not have impact factors. New journals must wait until they have a record of citations before even being considered for inclusion. Another important fact to note is that the scientific worth of an individual article has nothing to do with the impact factor of a journal. So scholars must be careful with the way articles are judged based on Impact Factor or even JCI reports.