The Impact Non-Factor
In July, 2016, the American Society for Microbiology (ASM) – responsible for 8 different biomedical journals – stated: “Despite widespread condemnation of journal Impact Factors to assess the significance of published work, these numbers continue to be widely misused in publication, hiring, funding, and promotion decisions.”2 The ASM leadership and Editors of ASM journals made the decision to remove reference to the Impact Factor from all ASM journals, and from related informational or promotional materials. They further noted: “The relentless pursuit of high Impact Factor publications has been detrimental for science.”
The May, 2017 issues of the Journal of Clinical Pharmacology and Clinical Pharmacology in Drug Development – two scientific journals owned by the American College of Clinical Pharmacology (ACCP) and published by Wiley – contained simultaneous editorials stating that reference to the Impact Factor would be removed from the journals and their web sites, and from any informational material made available from the ACCP.3
How did we get here?
The late Eugene E. Garfield passed away in February, 2017, at the age of 91. He was a prodigious intellect and a pioneering innovator in the field of citation science. His 1955 article in Science proposed the concepts of a citation index for science, and an Impact Factor for journals.4 The journal Impact Factor was actually anticipated to assist libraries in the selection of journals to which they would subscribe.4,5 Garfield went on to found the Institute for Scientific Information, and was behind the founding of Current Contents, Science Citation Index, Journal Citation Reports, and The Scientist. The current iterations of these enterprises are controlled by a single large media conglomerate.
Calculation of the Impact Factor is deceptively straightforward. For a given journal in a given calendar year, the Impact Factor is the total number of citations to publications in that journal for the two previous years divided by the total number of citable items appearing in that journal during the same two previous years. It is, essentially, an attempt to quantitate the average number of citations per article over the most recent two-year period.
Two major drawbacks are evident, and have been discussed for decades.6–9 First, most journal article citations happen well after the initial two years following publication – the Impact Factor will therefore fail to capture most of an article’s citations. Second, the citation pattern among articles is highly skewed – the majority of total citations can be attributed to a few highly-cited papers.