Nature Nanotechnology on reviewer performance statistics
How many papers does the typical researcher review in a year? How long do they take? And why do they do it? For the answers, read the Editorial in this month's (March) issue of Nature Nanotechnology, "Who'd be a referee?" (3, 119; 2008). The Editorial reports some of the findings of the recent Publishing Research Consortium report on peer-review (previously discussed at Peer to Peer), whose survey revealed that the "average review takes about 8.6 hours (with a median of about 5 hours) and is completed within 3–4 weeks, although there are significant differences between the four broad subject areas covered by the survey: in the physical sciences and engineering, for instance, the average (mean) is 10.4 hours, compared with 6.3 for clinical researchers. Of course, on top of this, many researchers spend considerable time reviewing grant applications for funding agencies, which can be equally onerous and possibly even more important than reviewing papers."
For similar statistics, and a more general discussion of the peer-review process in publishing, see the Nature Nanotechnology Editorial, or see here for Nature Cell Biology's take.