Academic Publishing Demystified

The Journal Impact Factor (sometimes abbreviated to JIF or IF) is a metric that has been in use for decades. Initially created as a tool to help librarians decide which journals to subscribe to, it has changed over the years to be used in a variety of ways.

While some scholars still use the JIF to drive publication decisions, the many limitations of this metric mean that it is important not to use it as a proxy for the quality of an individual research output or for an individual researcher's contributions.

What does the impact factor measure?
The Journal Impact Factor measures the frequency with which the “average article” in a journal has been cited in the last two years. As such, it may help reflect the importance of a journal in its field.

How is the impact factor calculated?
The Journal Impact Factor is the average number of times articles from the journal published in the past two years have been cited in the JCR year. The Impact Factor is calculated by dividing the number of citations in the JCR year by the total number of articles published in the two previous years. An Impact Factor of 1.0 means that, on average, the articles published one or two year ago have been cited one time. Citing articles may be from the same journal; most citing articles are from different journals. More details as well as graphical representations are available via Clarivate.

Who produces the impact factor?
The Journal Impact Factor is calculated every year in the Journal Citation Reports (JCR) database. JCR has been releasing impact factor data annually since 1975. The criteria and calculations used to calculate the metric have changed over time. 

Do all journals have an impact factor?
No. Journals indexed in the databases Science Citation Index Expanded or the Social Sciences Citation Index receive a Journal Impact Factor. Inclusion in these databases is competitive and require journals to meet certain criteria.

Just because a journal does not have an impact factor, does not mean that it is of low quality or low impact in its field.

Journals can be removed from the JCR database for a number of reasons, including unethical behaviour.

Is there more than one metric for measuring journal impact?
As a new academic author, it is easy to become overwhelmed by the number of metrics promoted by various publishers! There are a number of other metrics that purport to measure the impact of journals; however, the Journal Impact Factor continues to be the most influential. Other journal impact metrics include:

• Cite Score: This metric is similar to the Journal Impact factor, but uses a slightly different calculation (e.g. a four year time period rather than two), and is produced by a different company. Can be found in the Scopus database.
• Eigenfactor: This metric is intended to give a measure of how likely a journal is to be used, and is thought to reflect how frequently an average researcher would access content from that journal.
• Source Normalized Impact Factor (SNIP): This metric measures contextual citation impact by weighting citations based on the total number of citations in a subject field. The impact of a single citation is given higher value in subject areas where citations are less likely, and vice versa.  As such, SNIP is meant to correct for differences in citation practices between various fields, thereby allowing for more accurate between-field comparisons of citation impact. Also found in the Scopus database.

Is impact factor important in my discipline?
Use of the impact factor to drive publication decisions is very field specific. Talk to your advisor, mentors, and peers to find out if this metric, or any others, are important in your discipline. At an institutional level, the University of Calgary signed on to the Declaration on Research Assessment (DORA) in 2021. DORA explicitly guides against using the impact factor in decisions relating to funding, appointment, and promotion. 

What is a "good" impact factor?
This is a very difficult question to answer! The numerical value of impact factors varies greatly between disciplines and even sub-disciplines, due to different publishing and citing patterns. You can take a look at how journals are ranked by discipline by performing a subject search in Journal Citation Reports. This will help you understand what high impact journals in a particular field are.

What are some criticisms of the impact factor?
There is a large body of research pointing to the flaws and inappropriate uses of the impact factor and other research metrics. Some key criticisms include:

• Citation distributions within journals are highly skewed: for example, one "blockbuster" paper or highly cited item such as a review can artificially inflate the metric.
• Journal Impact Factors can be manipulated (or “gamed”) by editorial policy. For example, editors may encourage prospective authors to cite other items published in the same journal.
• Data used to calculate the Journal Impact Factors are neither transparent nor openly available to the public.

Unless otherwise noted, content is this guide is licensed under a Creative Commons Attribution 4.0 International License.