) include the effects of ‘influencing variables’ (e.g. Ī journal´s IF in a given year results from the equation of citations to this journal within the particular year to articles published in this journal during the two previous years, divided by the number of citable articles (“substantive articles and reviews” ), the so-called source items, which were published in these two precedent years.Ĭoncerns on the validity of the IF or its actual meaning (for overviews, see e.g. ), the IF continues to play a dominant role in academic career development. Consequently and despite attempts to develop more significant metrics (e.g. Originally developed as a guideline for librarians to compare journal quality within particular scientific subject categories, the IF is being applied likewise to measure and compare the scientific output of individuals or institutions. Therefore, careful consideration of the details of the IF equation and possible implementation of control mechanisms versus the volatile factor of number of articles may help to improve the expressiveness of this metric.ĭespite the well-known concerns and critique of the meaning and validity of the (Journal) Impact Factor ((J)IF), it continues to be a widespread instrument for the assessment of scientific output. The results of this analysis point out the potentially delusive effect of IF increases gained through effective shrinkage of publication output. The sample cohort features a considerable incidence of IF increases (18%) which are qualified as `invalid`according to this classification because the IF increase is merely based on a favorably changing number of articles (denominator). Along with the variation by number of articles and citations, this analysis includes the relative change of both variables compared to each other and offers a classification of `valid`and `invalid`scenarios of IF variation in terms of the intended goal of the IF to measure journal quality. A cohort of JCR-listed journals which faced the most dramatic absolute IF changes between 20 (ΔIF ≥ 3.0, n = 49) was analyzed for the causes resulting in IF changes that theses journals have experienced in the last five years.
citations / articles as the numerator / denominator of the quotient). This study provides a systematic analysis of significant journal Impact Factor changes, based on the relative contribution of either one or both variables of the IF equation (i.e. Both the concept and the application of the impact factor (IF) have been subject to widespread critique, including concerns over its potential manipulation.
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