Do fixed citation windows affect the impact maturation rates of scientific journals?

ABSTRACTScientific fields employ distinct citation practices. As such, bibliometric indicators based on citations need to be standardized to allow comparisons between fields. This paper examines more than six hundred journals in eight JCR categories. Results indicate that impact maturation rates vary considerably from one category to another. The time elapsed until the citation distribution reaches a maximum oscillates between two and five years; hence the opening and closing of the citation window is crucial to the impact factor. Some journals are penalized by the two-year impact factor and benefited by the five-year impact factor, and the reverse situation was also found. Nonetheless, there are impact factors of variable citation windows that produce closer measures of central tendency

Uncertainty measures for economics journal impact factors

Academic economists appear to be intensely interested in rankings of journals, institutions, and individuals. Yet there is little discussion of the uncertainty associated with these rankings. To illustrate the uncertainty associated with citations-based rankings, I compute the standard error of the impact factor for all economics journals with a five-year impact factor in the 2011 Journal Citations Report. I use these to derive confidence intervals for the impact factors as well as ranges of possible rank for a subset of thirty journals. I find that the impact factors of the top two journals are well defined and set these journals apart in a clearly defined group. An elite group of 9-11 mainstream journals can also be fairly reliably distinguished. The four bottom ranked journals are also fairly clearly set apart. For the remainder of the distribution, confidence intervals overlap and rankings are quite uncertain