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Re: What does 95th %tile mean?
On Fri, 20 Apr 2001 Toby_Williams@enron.net wrote: > _95th%ile is not a robust mechanism for billing_ > It neither addresses variance nor average use effectively and can be gamed > quite easily. It's some kind of best fit system for billing buyers with "normal > behaviour". > > Where in maths class did they ever say that scraping off the highest n percent > of a data set in isolation, gives a good indication of anything? Don't you need > to look at the mean and 90th percentile together to fairly evaulate > distribution. > > I think the reason it's so popular currently is that it's easy to describe > (hence sell) and fits normal use reasonably well, so from a "normal buyer's" > perspective is OK. Just as long as everyone is honest. Absolutely. Here's a scheme that, if everyone was using only 95th percentile billing, would give you webhosting at gigabit rate while only paying 30x minimal rate webhosting: a) colocate hardware at 30 different datacenters at gigE speed, but billed for 95th percentile. b) have a DNS server that rotates records, pointing to a different server each day. c) bingo. Each of your providers will remove highest 95th percentile (1.5 days worth of traffic) and only bill you for minimal utilization. -alex