[at the risk of dampening the whole nanog atmosphere by throwing real operational data in to this thread] nevil wrote a paper 2 years ago on use of 75th percentile ("3rd quartile day") for his academic network http://www.auckland.ac.nz/net/Accounting/3qd-kaw.pdf http://www.otago.ac.nz/ITS/ts/Kawaihikoservices.html (nice work, tho for unrelated political reasons that network happens to not exist anymore so there's not really a source of longterm data since 99 on it but there we are) k