On Mon, Sep 23, 2002 at 04:07:47PM -0400, Richard A Steenbergen wrote:
On Mon, Sep 23, 2002 at 12:50:17PM -0700, Lane Patterson wrote:
And there are at least 4 ways of computing 95th percentile, though I'm sure there've already been threads on this.
There is only one way, anyone else is computing "something else" that they just happen to bill with. But this sounds like a subject for the NANOG FAQ. :)
I think the problem is not that there are multiple definitions of how to calculate the 95th percentile of a sample population, but that different peoples' sample populations are constructed in different ways. I have seen billing based on: max(95th(to_cust), 95th(from_cust)) 95th(max(to_cust, from_cust)) 95th(to_cust + from_cust) 95th(to_cust) all referred to by different people as "95th percentile billing". There are also many different ways of obtaining values for "to_cust" and "from_cust", just to keep things interesting. I would be interested to find out how many customers of services billed by "95th percentile" do their own measurements and compare them with the bill. I suspect the number is not large. Maybe that's why most providers don't find it necessary to spell out exactly what calculations they are doing in order to arrive at a monthly figure with a dollar sign in front of it. Joe