I've been trying to come IP with a good way to get a somewhat accurate value. I was thinking maybe some sort of standard deviation, but even that proved erroneous. I think the trick will be to get a certain number of consecutive values close together within a 5 minute range. So, if I see something like: 280,274,281,260,96,91,280,290,277,248,62,54,289,277,291,265
I know to just drop the smaller sets.