Replicated observations in metrology and testing: modelling repeated and non-repeated measurements

摘要

In order to choose the right statistical tool, a basic issue for an accurate analysis of each specific problem is to understand whether the set of replicated measurement results under examination is to be considered as pertaining to repeated measurements or not. This issue is particularly important, since most of the traditional tools are valid only for repeated measurements, but, in many cases, such as laboratory comparisons (in metrology and in testing), the measurements necessary to assess correctly the measurand value and the associated uncertainty do not represent repeated measurements. The analysis performed in this paper aims to shine some light on these issues, starting with a review of the basic concepts, such as repeatability, reproducibility, accuracy, systematic error and bias, as defined in international documents and as used in the literature. The paper shows that, currently, a full consensus on a common language and understanding has not yet been achieved, and then shows how this fact reflects on the basic data models, especially those concerning inter-comparison data.