A simple method to determine the quality of a measuring instrument is to evaluate its discriminating capacity of the different samples subjected to measurement and also the presence or absence of measurement errors.
Very interesting is the evaluation of the behavior of the staff who performs quality measures, for example, of how a hotel room was cleaned after the customer left, or of the staff performing a tasting of a typical dish or a fine wine.
The measures could be in this form:
Tool (or person) # 1:
Tool (or person) # 2:
In the first case we have a tool / person who has a small margin of uncertainty and is able to clearly see the quality differences between the various “samples” subjected to inspection with relatively few measurement errors while for the second instrument / person we have an area of broader uncertainty, that is, it is not good to see the differences between one sample and another, it also presents more problems in assessing the quality of the sample subjected to inspection.