Characteristics of journal impact factors: The effects of uncitedness and citation distribution on the understanding of journal impact factors

Summary In this study, journal impact factors play a central role. In addition to this important bibliometric indicator, which evolves around the average impact of a journal in a two-year timeframe, related aspects of journal impact measurement are studied. Aspects like the output volume, the percentage of publications not cited, and the citation frequency distribution within a set timeframe are researched, and put in perspective with the 'classical' journal Impact Factor. In this study it is shown that these aspects of journal impact measurement play a significant role, and are strongly inter-related. Especially the separation between journals on the basis of the differences in output volume seems to be relevant, as can be concluded from the different results in the analysis of journal impact factors, the degree of uncitedness, and the share of a journal its contents above or below the impact factor value.