Some overdue thoughts on impact factors

OK, I know this is late (they were released in July!), but the recent editorial board meeting in Tübingen forced me to put the vague thoughts I had about the 2010 impact factors into actual words and pictures:
Molecular Ecology did very well, moving from 5.96 to 6.45, and kept at fifth in the evolution rankings. Since the journals above Mol Ecol are two systematics journals (Systematic Biology and Cladistics) and two reviews-only journals (TREE and AREES), we’re very pleased with how it’s going. Furthermore, if you multiply the number of papers published per year by the impact factor (Loren’s somewhat tongue in cheek ‘Clout Factor’), you can see that Mol Ecol is putting out a lot of good papers:


MBE’s story this year is one to make most editors shudder- they published the phenomenally successful Tamura et al paper describing MEGA 4.0 in 2007, and it went on to gather over 1500 citations. In the process, MBE’s impact factor rose all the way to 9.87 in 2009. However, the 2010 IF doesn’t consider papers published in 2007, and hence they plunged to 5.51 this year. The good news is that the paper describing MEGA 5.0 is in press as of May 2011, so the roller coaster is heading back up the hill.
Molecular Ecology Resources pretty much stayed where it was, at 1.63, but don’t let the apparent lack of action fool you. Since the journal published its last stand alone primer note at the end of 2009, the output of the journal has fallen from 400 to 150 papers a year, but each of these is gathering many more citations. The net effect is that the 2011 impact factor will be over 2, and the 2012 IF will rocket to somewhere over 5:

I’d be happy to make the numbers underlying this 2011 and 2012 projection available, but it’s an ugly table with lots of footnotes. In a nutshell, they’re based on the observation that the 142 papers we published in 2010 were cited 352 times between January and July 2011, and that papers in MER are cited (on average) 1.58 times more in the second year than they were in the first. Anyway, interesting times are ahead…