Thomson Reuter update: What is an Eigenfactor?

Anyone browsing the Thomson Reuters (ISI) website recently will have noticed a few new statistics on its indexed journals, including something called an Eigenfactor.

What on earth is an Eigenfactor?

Since February, ISI has started to include three new metrics in its Journal Citation Reports (JCR) pages alongside its better know Impact Factor. The Eigenfactor is a figure that purports to measure the impact of research an article/journal/author as part of the "bogy of knowledge" as a whole, hence the slightly strage-looking figures that include several decimal places. Related to this and also included by ISI is the Article Influence score, which is designed to give a similar sort of measure of the Impact Factor.

The third new metric is the addition of a Five Year Impact Factor, which extends Impact Factor from two years of citations to five years. The two year window has been much criticised, and the extended window is an attempt by ISI to modify the critics by allowing researchers to view a longer term of research impact.

Source: Emerald Global E-zine