Bruce, > Tom > > Its important to realise these calculated statistics are all estimators > of the underlying Allan variance. > Thus it is important to assign unique unambiguous names to each of them > so that some idea of their region of reasonable accuracy and perhaps > their confidence limits can be estimated.
It should be recalled that AVAR is actually not necessarilly a name as such but short-hand. To help making the issue complex, AVAR has been given as a name to denote a particular algorithm, just as MADEV, TDEV etc. Even if one can argue that they have these meanings within a specific context, the ambiguity problem is there as it makes it harder to compare results. > Thus for example: > AVAR doesn't actually denote the underlying Allan variance but rather a > particular algorithm used to estimate it from the data. > > OAVAR denotes another algorithm for estimating the underlying Allan > variance from the data Trouble is, the algorithm Tom and Ulrich wants to denote OAVAR others have already denoted AVAR, thus causing ambiguity. > TOTVAR, THEO1 and THEOH denote other algorithms that can be used to > estimate the underlying Allan variance from the data. > > Some of these algorithms produce biased estimates of the underlying > Allan variance so correction for such bias is usually necessary. The way the confidence interval closes on the estimate should be of a concern. We can calculate whatever we want, but as we try to judge the results of such estimates we should also view the indicators of its precision if available. 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.
