About the author

Dan Rhoads

Dan is a postdoc working at the University of Cyprus in developmental biology. He has a BSc in molecular biology and a PhD pharmacology and biochemistry.

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Thompson Scientific is great for gaging the impact factors of various journals, but it has had a bit of a monopoly on journal rankings. As with any ranking scheme, there can be more than one valid way of comparing alternatives.

Enter a new ranking tool – that’s free – the SCImago Journal Rank database. This ranking tool calculates papers’ impact factors using a new algorithm similar to PageRank, the algorithm Google uses to rank web pages, and was launched in December by SCImago, a data-mining and visualization group in Spain. It ranks journals and countries using such citation metrics as the popular, if controversial, Hirsch Index. It also includes a new metric: the SCImago Journal Rank (SJR).

In contrast, he familiar impact factor created by industry leader Thomson Scientific, based in Philadelphia, Pennsylvania, is calculated as the average number of citations by the papers that each journal contains – basically treating all citations as equal. Is that a valid premise however? SCImago says no (as with the Google PageRank algorithm), and makes a strong case. Afterall, we naturally and automatically prioritize citations based on where they’re coming from.

Practically speaking though, the more metrics we have the better. Compare weighted and unweighted citation analyses when comparing competing journals… so long as Thompson Scientific improves transparency over how citation metrics are calculated and the data sets used.

• D. Butler, Nature 451:6 (2008). DOI:10.1038/451006a
• SCImago Journal Rank database
• M. Rossner et al., J. Cell Biol. 179:1091–1092 (2007). DOI:10.1083/jcb.200711140