The impact factor has somewhat lost its prominence while being the most established and possibly the most used citation metric. In recent years, the impact factor has received widespread criticism for its shortcomings, and the academic research community is actively seeking other metrics that are better predictors of study quality.
This has resulted in the rise of metrics such as the h index, Eigenfactor score, and a number of article-level metrics based on how articles are shared via social media.
As a result, more people are questioning the impact factor’s validity. In fact, a recent study, which is freely available on arxiv, appears to show that the era of the impact factor as we know it may be coming to an end.
The authors of this study examined the relationship between a journal’s impact factor and the amount of citations earned by individual articles in that journal over a 100-year period (1902–2009). Their hypothesis that this relationship should be declining, particularly since the 1990s, was supported by a compelling argument that the impact factor was critical at a time when researchers had to read entire issues of print journals to identify articles of interest.
The study’s authors predicted that this association would decline, especially since the 1990s. They argued that the impact factor was critical when researchers had to read full print journal issues to find relevant articles and librarians used it to determine which journals to include in their collections.
However, in the digital age, researchers can easily find articles through online keyword searches without needing to peruse entire journals. As a result, the impact factor of a journal is becoming less significant.
In line with their hypothesis, the study revealed that the correlation between journal impact factor and actual citations per article has been declining over the past two decades. This trend is observed across all subject areas.
Additionally, the study investigated the proportion of the top 5–10% most highly cited papers that were published in the top 5–10% of journals (based on impact factor) within their fields, finding that this proportion has notably decreased over the same period.
Thus, the significance of the impact factor is diminishing both in absolute terms, as indicated by the study, and in the perception of academic researchers.
While funding committees may still consider the impact factor of journals when reviewing grant applications, it is unlikely to be the sole criterion. As discussed in a previous post, the h index is a more dependable measure of researcher quality compared to the impact factor.
To present a comprehensive picture of your research quality and mitigate any negative impressions from low-impact-factor publications, it is advisable to include a range of citation metrics in your application, such as your h index and other article-level metrics.
Clearly, if you have strong research objectives and demonstrated expertise, the impact factor is not the only factor that matters.
