Impact factor ‘eligibility window’ skews the system

By David Kent. For the past year, I have been sitting on the publications committee for a society-run journal and in the journal’s quest to improve its impact factor (IF), it became clear to me that one of the system’s dark secrets is the “window of IF eligibility.” It single-handedly disadvantages journals whose science stands the test of time and favours journals that have speedy public relations’ campaigns.
For those not aware of it, a journal’s IF is based on two numbers for year X:

1. The number of times articles published in the two years prior to year X are cited during year X
2. The number of citable articles published in the two years prior to year X

The IF is simply the first number divided by the second. More...