Journal influence factors

We performed a thorough comparison of four main indicators of journal influence, namely 2-year impact factor, 5-year impact factor, eigenfactor and article influence. These indicators have been recently added by Thomson Reuters to the Journal Citation Reports, in both science and social science editions, and are thus available for study and comparison over a sample of significative size. We find that the distribution associated with the eigenfactor largely differs from the distribution of the other surveyed measures in terms of deviation from the mean, concentration, entropy, and skewness. Moreover, it is the one that best fits to the lognormal theoretical model. Surprisingly, the eigenfactor is also the most variable indicator when computed across different fields of science and social science, while article influence is the most stable in this respect, and hence the most suitable metric to be used interdisciplinarily. Finally, the journal rankings provided by impact factors and article influence are relatively similar and diverge from the one produced by eigenfactor, which is closer to that given by the total number of received citations. (C) 2009 Elsevier Ltd. All rights reserved.