The delicate topic of the impact factor

Abstract

In the early 1960s, Irving H. Sher and Eugene Garfield created the journal impact factor (IF) to help select journals for the new Science Citation Index (SCI). They quickly recognised that small journals which specialise in certain topics may not be selected if dependent solely on total publications or citation counts. A simple method was then required for journals, regardless of size or citation frequency—the impact factor [1]. A journal’s IF is based on two elements: the numerator, which is the number of citations in the current year to any items published in a journal in the previous 2 years, and the denominator, which is the number of substantive articles (source items) published in the same 2 years. Experience has shown that in each specialty the best journals are those in which it is most difficult to have an article accepted, and these are the journals that have a high IF. The use of the impact factor in research evaluation Particularly in Germany, as in Austria and in Japan, the IF has developed significant influence beyond its original goal. In these countries, research assessment rests too heavily on the inflated status of the impact factor. In its original sense, the IF represents a comparative measure of the quality of a journal. The IF simply reflects the ability of journals and editors to attract the best papers available [2]. Hence, the IF stands for the quality of the journal and not for the quality of the individual paper. In practical use in Germany, however, the IF of the journal is taken as a measure for the individual paper. Furthermore, the journal’s IF is attributed to each author of that specific article, irrespective of the number of authors and the contribution he or she made to this article. The individual citation rate of an author or article is totally neglected in this system. Despite evident limitations, the IF is very influential. Although even Thomson Scientific acknowledges that the impact factor has grown beyond its control and is being used in many inappropriate ways, the impact factors of journals have been used to decide whether or not authors get promoted, are given tenure or are offered a position in a department, or are awarded a grant. In some countries, especially in Europe and Japan, government funding of entire institutions is dependent on the number of publications in journals with high impact factors. Finally, the sum of IF points of a person is considered as a measure of his individual research quality. This has obvious appeal for an academic administrator who knows neither the subject nor the journals [3]. Seglen points out that about 15% of the articles in a typical journal account for half of the citations gained by that publication. This means that an average paper in a journal with a high impact factor may not, in fact, be cited much more frequently than the average paper in a lower-ranking journal. Therefore the IF of the source journal should not be used as a substitute measure of the citation impact of individual articles in the journal [4].