Karl Fogel at
For running a meeting, the prep time is (usually, all other things being equal, etc) proportional to the duration of the meeting, and that ratio in turn varies with the number of participants (you prep more for 1000 people than for 5).
Does anyone know what (PREP/MTG)/PPL is?
I had to express the formula crudely because I was running out of tweet room. Of course, prep time actually goes up with number of attendees, so the useful formula might be "PREP = [(Nth root of MTG_DURATION) * (Mth root of PPL)]", where N and M are not necessarily integers.