Impact Factors

In 1955, Eugene Garfield first proposed the idea of an index to measure how often a journal's articles were cited. This was before the internet (you knew that, right?) and he was looking for an easy way to sort information. The goal was to distinguish the small-but-often-cited journals from the small-and-not-very-useful journals.

Journal Citation Reports (JCR) publishes the list of impact factors each year. These are the ones journals brag about, the ones that are listed in the journal (or on the "About this Journal" section, if you read journals online.) They are frequently misinterpreted, and subject to numerous criticisms. But what I really don't like about them is that they are expensive, and JCR enforces its copyright and doesn't allow lists of impact factors to be posted legally. So the only way my students can compare impacts factors of a series of journals is to look each one up individually, or find them illegally posted on scribd.

But there are LOTS of alternatives to JCR Impact Factors. My favorite is Eigenfactor. (Don't worry, it has nothing to do with eigenvectors).   Their statistics seem more meaningful, you can compare different disciplines, they include cost effectiveness rankings, and they are completely free and searchable. But they also do a lot of great visualizations. You can easily look up any field and see which journals publish the most articles and which journals publish the most influential articles, how fields are related, changes over time, etc. Being able to see how journals relate to each other gives a much better understanding of scientific literature than one statistical indicator.