The journal impact factor is a metric used to gauge the relative importance of a particular journal relative to other journals in its field. For scholars, being published in a journal with a high impact factor is a sign of prestige. It can carry considerable weight if you eventually apply for a position at a university or research institute.
A journal's impact factor is calculated by tallying, for a given year, the number of citations to its articles published over the previous two years, and dividing that figure by the total number of articles published in the journal over the previous two years. (See the Journal Citation Reports published by Thomson Reuters.)
Advantages
As one of the oldest and most used metrics for evaluating the impact of scholarly journals, the journal impact factor has a number of different advantages when it comes to evaluating the impact, importance and significance of a scholarly journal one may wish to publish their work in. These advantages include, but are not limited to, how well known the journal impact factor is, how easy it is to calculate and how it accounts for journals of different sizes and ages.
Renown
- Has been in use since 1950
- Well-established and well-respected measure of the importance and significance of a journal and its articles
- Other scholars understand the prestige of being published in a journal with a high impact factor
Simplicity
- Simple calculation (journal's average number of per-article citations to articles published in that journal over the previous two years)
Equality
- Does not discriminate against smaller journals that publish infrequently or more mature journals
- A journal that publishes a handful of quality articles each year can have a higher impact factor than one that publishes many lower quality articles
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Disadvantages
Despite its popularity and widespread adoption, the journal impact factor has a number of disadvantages and flaws that scholars must be aware of, such as using self-citation to artificially boost the impact factor, publishing a large number of review articles and the "eigenlob" author self-citation phenomenon.
Self Citation
- Some publishers may require their authors to reference articles already published in that journal, therefore bumping up its impact factor
- Some journal publishers may enter agreements with other publishers and require their authors to cite each other’s journals, therefore raising all of their impact factors
Review Articles
- Journals may publish a large number of review articles that quickly and efficiently inflate their impact factor, since review articles typically receive many more citations than original articles
- As a result, scholars who choose a journal to publish in based on its impact factor may be selling themselves short, since "60% of the top 25 journals, as ranked by the ISI impact factor, are journals publishing only reviews and summaries of past research" (Falagas & Vangelis 224)
Eigenlob Author Self-Citation Phenomenon
- In order to take advantage of how the journal impact factor is calculated, some journals may only accept authors who publish a lot of research, which includes citing their own work
- Journals may also prefer to publish papers that have many authors, as this increases the chance of self-citation and so increases that journal’s impact factor
Sources
Nisonger, T. E. (2004). The benefits and drawbacks of impact factor for journal collection management in libraries. The Serials Librarian 47(1): 57-75.
Falagas, M. E., & Alexiou, G. V. (2008). The top-ten in journal impact factor manipulation. Archivum Immunologiae et Therapiae Experimentalis, 56(4), 223-226.
Further Reading/Viewing
The Clarivate Analytics Impact Factor
Journal Citation Reports - Journal Impact Factor