Posted for Emma Marris

The Eigenfactor website has some cool new tools.

For those not au currant with this metric, I will explain. The Eigenfactor, developed by a group out of the University of Washington led by Carl Bergstrom seeks to rank journals not just by impact but by value for money.

First, the influence of a journal is determined by a method that the group describes as more Google than Thompson ISI. Then this influence is multiplied by a measure of how many articles appear in each journal and how much each journal costs.

The result is a ranked list of which journals offer most influential content for the least money, and is one of a new crop of alternate impact factors (see our piece on SCImago Journal & Country Rank database) The fact that Nature is ranked as the top science journal by Eigenfactor in no way influences our interest in the tool…I swear.

Anyway, the site has been up for a while, but some neat new applications, based on Gapminder and made with Google Docs have appeared in the last week or so. Motion charts show how a journal’s Eigenfactor (or influence) change over time. The x and y axis can be assigned different variables; journals are represented by dots that can be clicked to display their trails through time; graphs can be switched between logarithmic and linear.

I met up with Carl last week, and he showed me the new toy and we chatted about his hopes for Eigenfactor. Interestingly, he says that his researches in the field have uncovered a significant amount of “citation inflation”.

That is, the average paper cites more other papers these days than it would have in the past. Check his paper on this out at arxiv. It’s not yet clear why this is happening. One of Carl’s collaborators suggested that there was just more previous literature to draw upon. Carl reckons it is a change in citation culture. I wonder if authors these days are more timid about asserting things on their own without a citation. It is also possible that they are just trying to demonstrate that they’ve read all the relevant papers. At any rate, citation inflation means that impact factors are slowly increasing over time.