How much should we review?

There’s an discussion going on over at Crooked Timber on how many papers one should agree to review. Most of the commenters are in the social sciences, but one pointed to an essay by William F. Perrin in a recent issue of Science that suggests the following formula:

R = \kappa \cdot S

where R is the number of reviews you should do, \kappa is the number of reviews required per paper, and S is the number of papers you have submitted. I’m guessing that means “papers on which you are the primary author,” but the formula seems reasonable. I wonder how the reviewing load for the Transactions on IT is actually distributed. Perhaps that might be a good survey for the IT Society, or maybe statistics can be gathered from the Pareja database.