Checking for the inadequacy of models of measurement objects as a necessary condition for the applicability of the “Guide to Expression of Uncertainty in Measurement”

The condition of applicability of the “Guide to the Expression of Measurement Uncertainty” (GUM), a translation into Russian in 1999 of the international document on metrology, is considered. The GUM is devoted to a new approach for domestic metrology at that time to assessing the accuracy of solving measurement problems using the indirect measurement method. The condition of applicability requires the negligible smallness of any uncertainties caused by the incompleteness of determining the quantities sought in the problem compared to the required accuracy of the result, although the translation states that “this is not always practical”. However, the VIM-3 International Dictionary of Metrology Terms introduced the term “defi nition uncertainty” for uncertainties of this kind and pointed out that in the GUM, defi nitional uncertainty is considered as negligible compared to other components of measurement uncertainty. In practice, there are numerous cases of using the GUM without checking mathematical models for inadequacy. The situation is aggravated by the fact that this manual does not contain a quantitative defi nition of the incompleteness of the mathematical model of the measuring object, although the need for statistical verifi cation of models for inadequacy is mentioned. Violation of the condition of applicability of the GUM can be eliminated by a cross-examination scheme.

functional dependence, measurement uncertainty, inadequacy, defi nition uncertainty