Evaluation of the type A uncertainty in measurements with autocorrelated observations

Described is the proposal of application of the GUM uncertainty type A evaluation to measurements with auto-correlated observations. The first step to it is the identification and cleaning of the raw sample data from the regularly variable components. Then formulas for standard deviation of the sample and of the mean value are expressed with the use correction coefficients or the so-called "effective number" of observations. These quantities depend on number of observations and on the sample autocorrelation function and allow to calculate the expanded uncertainty due to the GUM recommendations. The method of estimation of autocorrelation function for the sample data is also given. Considerations are illustrated by examples.