eigenfactor.org

Eigenfactor.com is a relatively new website that provides ratings for academic journals. It's main competitor is the venerable Journal Citation Reports from ISI and in the field of economics impact factors computed by RePEc from the information in their database. Eigenfactor actually derives its data from ISI. It uses the record of citations in a given year to articles published in the previous five years. Journal Citation Reports is now also giving five year impact factors in addition to its traditional two year impact factors as well as eignefactor.org's results. The two year impact factor (e.g. average number of citations in 2008 to articles published in 2006 and 2007) has always been very inadequate in a field like economics where there are long publication delays and articles also tend to stand the test of time relatively well.

Eigenfactor.org appears to use a recursive impact index (citations in more highly cited journals count for more than citations in low prestige journals) in a similar way to RePEc with some adjustment for differences in citation rates across disciplines. They ignore self-citation by journals. The Eigenfactor score is based on total citations for the journal while the Article Influence Score is a per article measure that is closer to traditional impact factors. You can learn much more about the methods at their website.

To compare the different indicators I made a table for three of the top journals in each of energy and environmental economics:



I used the 2008 Article Influence Scores available from Journal Citation Reports. The most recent scores available for free on the eigenfactor.org website are for 2006. JEEM is clearly the top environmental economics journal - it doesn't matter which indicator you use. When you limit citations to only those in the economics literature as RePEc does, Ecological Economics appears much weaker than when all possible citations are included. This confirms our findings that Ecological Economics tended to be cited more in interdisciplinary outlets. Energy Policy too is weak in the economics sphere and generally appears to be cited in less prestigious journals than the Energy Journal does.

I've also noticed that the relative rank of the Energy Journal has declined over time while that of Energy Economics has risen. Energy Economics' Article Influence Score was only 0.51 in 2006 while the Energy Journal's was 0.957.