Foundations of uncertainty in evaluation of nominal properties

Measurement uncertainty is a key component of metrology but, as it is defined, it does not apply to nominal properties. The possibility to define, evaluate, and express the uncertainty in the examination of nominal properties is then a critical prerequisite for a harmonized treatment of nominal properties in metrology. The assumption at the basis of this paper is that examination uncertainty can be understood in analogy with and as a generalization of measurement uncertainty. To this aim a foundational framework is introduced, grounded on a generic concept of evaluation uncertainty that applies equally to quantitative and non-quantitative evaluations. Based on this, a concept of examination uncertainty is presented and some examples of mathematical functions of examination uncertainty are proposed.