On the degree of objectivity of uncertainty evaluation in metrology and testing

The general problem of the subjective vs objective level of knowledge is widely and extensively treated in the literature. The paper intends to limit the discussion from the viewpoint of the metrologist to some aspects related to the concept of ‘true value’, abandoned by GUM but still present in other international reference documents, and about the use of non-quantitative information or of prior knowledge in connection with the uncertainty evaluation in measurement.