%0 Journal Article
%T Reliability of journal impact factor rankings
%A Darren C Greenwood
%J BMC Medical Research Methodology
%D 2007
%I BioMed Central
%R 10.1186/1471-2288-7-48
%X Based on citations to journals in research and experimental medicine in 2005, Bayesian Markov chain Monte Carlo methods were used to estimate the uncertainty associated with these journal performance indicators.Intervals representing plausible ranges of values for journal impact factor ranks indicated that most journals cannot be ranked with great precision. Only the top and bottom few journals could place any confidence in their rank position. Intervals were wider and overlapping for most journals.Decisions placed on journal impact factors are potentially misleading where the uncertainty associated with the measure is ignored. This article proposes that caution should be exercised in the interpretation of journal impact factors and their ranks, and specifically that a measure of uncertainty should be routinely presented alongside the point estimate.Journal citation reports are used widely as the basis for assessing research output. They are used by funding bodies to gauge the quality of publications, by researchers to assess which journals they choose to submit manuscripts to, and as a basis for journals to attract new subscriptions and advertising [1]. In addition, current discussion surrounding the future nature of the UK Research Assessment Exercise (RAE) involves greater use of such bibliometric data [2,3]. The journal impact factor is the most widely cited bibliometric tool used to characterise journals. It was originally proposed 50 years ago as a measure of the impact that individual articles have on the research community [4], but it is now more commonly used across all articles published by a journal to provide a measure of a journal's impact on the research community rather than the impact of an individual article [5]. The journal impact factor is thus calculated as the number of citations a journal has received in the last complete year for articles published in the two preceding years, divided by the total number of articles the journal published in the
%U http://www.biomedcentral.com/1471-2288/7/48