Importance of Using Impact Factors When Choosing Your Target Journal

Selecting a journal in which to publish their study is an important and difficult decision for researchers. With more than 80,000 academic, peer-reviewed English language journals active as of July 2019¹, the question of how to choose the right journal for your manuscript is complex. Many factors play into the final selection, including the researcher’s familiarity with the publication, opinions of colleagues, and overall journal reputation. For decades, the journal impact factor (IF) has been used as a metric to evaluate journal prestige and influence and has helped numerous authors choose a target journal. But does the impact factor matter?

Although it is the oldest and most popular indicator of journal prestige, the IF has been subject to criticism lately due to its limitations and inappropriate use². This has led the academic research community to search for new metrics that might better indicate the strength and influence of research journals. Thus, new evaluation tools such as the Scimago Journal Rank (SJR), Source Normalized Impact per Paper (SNIP), Eigenfactor score (ES), and Article Influence Score (AIS) have emerged as alternatives for evaluating the impact of research journals.

Journal Impact Factor (IF)

So, what exactly is this IF metric that has influenced the publication intentions of so many researchers over the years? The IF, a product of the Journal Citation Report, is simply the average number of times each article in a specific journal has been cited in the past two years.

Despite its long-term popularity, the IF has limitations that have come increasingly under scrutiny by researchers. One of these limitations is the small, two-year time window. Another issue is the annual nature of the measure. For example, a 2018 IF of 2.153 means that the average article in this journal was cited an average of 2.153 times in 2017 and 2016 combined³. It also means that the 2018 IF numbers were not available until 2019, a year-long lag. In addition, the IF does not account for variations in citation averages across disciplines⁴.

As you can see, the IF measures the impact of the collection of all the articles in a journal and has nothing to say about an individual article or author. Thus, the recent use of this metric as an evaluation tool for a single article or researcher is misleading.

Other metrics to evaluate journal impact

Due to these limitations, researchers have been turning to other metrics to evaluate the quality and impact of a journal and to help them choose a target journal. Here are brief descriptions of a few of the indicators currently being used. 

• Scimago Journal Rank (SJR)

This metric is similar to the IF in that it is an indication of citation frequency; however, it gives more weight to citations from prestigious journals than to citations from lower-level journals^3,4. Thus, for two journals with the same number of citations, the journal cited most often by articles in more prestigious journals will have a higher SJR score. In addition, the time window for the citations is three years instead of the two years used by the IF. 

• Source Normalized Impact per Paper (SNIP)

The SNIP calculates journal impact scores by normalizing citations by field⁴. This eliminates the IF variations due to differences in the citation numbers across disciplines and makes the SNIP a more reliable indicator of a journal’s impact among disciplines. 

• Eigenfactor score (ES) and Article Influence Score (AIS)

The ES combines features of both the SJR and SNIP metrics^3,4. Similar to SJR, the ES gives greater weight to citations from more prestigious journals and, similar to SNIP, the citations are normalized by field. In addition, the ES indicator includes consideration of the time a researcher spends with each journal, with larger journals having higher scores. The AIS is also similar to the IF, except that it is calculated using the ES. Evidence suggests that both the ES and AIS are more robust indicators of journal quality than the IF³. 

• Altmetrics

All of these traditional metrics vary across disciplines and are subject to biases⁵. In addition, the number of citations tends to be greater for review articles, and the practice of self-citation can impact some indicators. Because of these issues and the increasing use of social media for research sharing, alternative web-based indicators are now being considered and used. These measures include the number of times a research study has been shared or downloaded on social media sites and other web-based locations. Altmetrics are useful as a complement to the more traditional indicators.

Rather than IF, using a combination of metrics to determine journal quality and influence will provide researchers with the best foundation on which to base a publishing decision. As always, researchers need to be vigilant about using any indicator without understanding its origin, limitations, and biases. 

References

1. Suiter AM, Sarli CC. Selecting a journal for publication: Criteria to consider. Mo Med. 2019 116, 461–465.
2. Cerejo, C. Is impact factor everything? Editage Insights. 2013. https://www.editage.com/insights/is-impact-factor-everything [Accessed August 2, 2022]
3. University of Connecticut. Evaluating journal quality — metrics. https://guides.lib.uconn.edu/journaleval/metrics [Accessed August 2, 2022]
4. Editage Insights. The impact factor and other measures of journal prestige. https://www.editage.com/insights/the-impact-factor-and-other-measures-of-journal-prestige [Accessed August 2, 2022]
5. Singh S. Important journal metrics all researchers should know about. Researcher.Life. https://researcher.life/blog/article/journal-metrics/ [Accessed August 2, 2022]