Dose 2016

How uncertainty is determined

Coming back to the situation of a measurement, we now introduce - according to GUM - the two definitions:

1) The best estimate of the value of the measurand is determined from its expectation value with respect to its associated probability density distribution. If this distribution is not known, it can be estimated as the mean value from a random sample obtained from repeated measurements. 2) The standard uncertainty u of the value of the measurand is determined as the positive root of the variance with respect to its associated probability density distribution. If this distribution is not known, the estimate of the variance of the mean value can be used instead.

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