Clay Shirky is on a mission to debunk the 'resident' numbers of Second Life that are routinely published by the game's makers (Linden Lab) and subsequently banded about by bloggers and journalists alike. And he's doing a pretty good job:
Linden's numbers also suggest that the Residents figure includes even failed attempts to use the service. They reported adding their second million Residents between mid-October and December 14th, but they also reported just shy of 810,000 logins for the same period. One million new Residents but only 810,000 logins leaves nearly 200,000 new Residents unaccounted for. Linden may be counting as Residents people who signed up and downloaded the client software, but who never logged in, or there may be some other reason for the mismatched figures, but whatever the case, Residents is remarkably inflated with regards to the published measure of use.
Like any social network's user numbers, there always exists a significant difference between the published number of sign-ups and actual 'active' accounts. But if Linden Lab are counting sign-ups who have never logged in, that may well be a first.