On 08/25/2013 08:25 PM, Bob Camp wrote: > Hi > > The most common approach is to *assume* that the two devices are not > correlated. SInce it's a negative, you really can't prove it. What you can do > is to disprove it by finding and documenting a correlation. > > ADEV it's self has a confidence level based on the number of samples taken. > What is normally reported is the calculated number, not the number plus the > uncertainty. The same carries over to the square root of 2. It's simply the > best estimate of what's going on. As long as they say what the do / do what > they say, it's not really a problem. > > The next step is typically to build a couple more devices and start doing a > simultaneous N way comparison. That will let you play with math and better > estimate the performance of each of your devices. The best case would be to > compare devices made by different labs using different approaches. That > usually lets you spot the correlation issues between devices. Exactly. As you have three devices, measuring them pair-wise you get three measures and three un-knowns, and you can untangle the stability of each individual. If you have yet more, you can get some confidence levels also as it becomes overdetermined.
Cheers, Magnus _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
