Abstract
I often receive inquiries from potential authors regarding the impact factor (IF) of the Journal of Histochemistry and Cytochemistry (JHC). The IF is a number calculated annually by Thomson ISI (Philadelphia, PA; www.isiknowledge.com) based on the frequency with which articles published in a given journal over a 2-year period are cited in the subsequent calendar year (Garfield 2006). For example, in 2005 there were 784 citations to the 355 articles published in JHC in 2003 and 2004; thus, the JHC IF for 2005 is 2.21. Between 2000 and 2005 the JHC IF has consistently been between 2.2 and 2.7, which typically places JHC in the upper half of the approximately 150 journals in the “Cell Biology” category. Keen interest in IFs extends beyond potential JHC authors, and recently the Editor-in-Chief of Laboratory Investigation, an excellent Pathology journal with a current IF of 3.86, commented that “Over these past 3 years our editorial office has established a weekly ‘ticker tape’ of Impact Factor status” (Crawford 2007). The question I pose to myself as an author of scientific manuscripts and Editor-in-Chief of the JHC is “How much does IF really matter?”
As a scientist, I have a strong desire to publish my work in high IF journals and subsequently have those manuscripts recognized by the scientific community as being significant as evidenced by their frequent citation. Publishing a manuscript in a low IF journal and having the work ignored is certainly not aspired to by any author. However, the majority of manuscripts submitted by scientists for publication fall somewhere between these extremes, and finding the right audience (i.e., journal readership) for one's manuscript is as important as the IF of the journal in which it appears. The IF of a journal is simply a predictor of the frequency with which an “average” article published in that journal will be cited over the next few years. It is silly to believe that all manuscripts published in a particular journal are equally good or bad, or that an article published in a journal with an IF of four is twice as good as an article published in a journal with an IF of two.
In reviewing my own publication record and the frequency with which particular manuscripts have been cited, it is safe to say that manuscripts published in high IF journals are almost always frequently cited. However, it is also apparent that citation frequency is not solely dependent on IF. For example, a manuscript that I published in JHC (current IF 2.21) has been cited over 120 times in the last 10 years (Shindler and Roth 1996). Several manuscripts that I published in Brain Research (current IF 2.3) have been cited well over 100 times (Roth et al. 1982a,b); still, others published in journals with IFs of less than two have been cited 20 or more times. In contrast, manuscripts that I published in Gastroenterology (current IF: 12.39) (Aiken et al. 1994) and Oncogene (current IF: 6.87) (Leonard et al. 2001) have been notable underperformers and cited only 10 times each, despite my feeling that they were good manuscripts and worthy of publication in these high IF journals. Given the modern search and citation analysis tools freely available online (www.isiknowledge.com; www.ncbi.nim.nih.gov; www.highwire.stanford.edu), authors, department chairs, and promotion and tenure committees can readily assess the citation frequency of published manuscripts without relying on aggregate journal IFs to assess publication quality.
If, as Editor-in-Chief, I judged that a higher IF was critically important to the mission of the JHC, I would immediately implement at least four changes in our publication efforts. First, I would solicit and publish more review articles. Review articles are typically well cited, particularly now that many journals limit the number of references permitted in a manuscript. Thus, many journals with high IFs consist exclusively of review articles or they publish a high proportion of review articles relative to primary data manuscripts. However, as I personally receive frequent requests from other journals to submit review articles on my area of expertise (neuronal cell death regulation), I ask myself, “Does the world's scientific literature really need another review article on this topic?”
Second, I would publish the review articles early in the year to maximize the time available for the reviews to be cited in other manuscripts. For example, in determining the 2005 IF for a journal, a review article published in January 2003 is potentially citable for 23 months (through December 2005), whereas an article published in December 2003 is only available for citation for 12 months. Because the IF is based on citations over a relatively short period of time, publishing highly “citable” manuscripts, i.e., review articles, early in the year is particularly important for journals such as JHC, whose typical article might not be rapidly cited but often has a long citation half-life. The JHC prides itself in publishing manuscripts that remain highly cited for many years, but such manuscripts do not increase the IF of our journal, given the formula for calculating IFs.
Third, I would accept fewer articles for publication. By eliminating manuscripts that may be of relatively narrow interest and unlikely to be highly cited, regardless of the quality of the work and whether or not the manuscript meets the Journal's mission, the IF denominator would be reduced, resulting in a higher overall IF for JHC.
Finally, as Editor-in-Chief, I would adopt a policy of strongly encouraging authors to liberally cite articles published in the JHC during the preceding 2 years. Note that referencing manuscripts published more than 2 years previously is not encouraged because such citations do not influence the IF calculation!
Although implementing the above options would undoubtedly increase the IF of the JHC, I doubt that doing so would be in the best interest of the JHC, its authors, or readers. Nor would such policies be consistent with the mission of the Histochemical Society, the Journal's publisher, or the JHC.
In total, there is no IF ‘ticker tape’ in the JHC office and, as Editor-in-Chief, I will continue to focus on publishing high-quality primary data manuscripts that I hope will be of significant interest to the JHC readership.