Traceability means that a measured result can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, all having stated uncertainties. The measure of trueness is usually expressed in terms of bias . Uncertainty of measurement is a parameter, associated with the result of a measurement, that characterises the dispersion of the values that could reasonably be attributed to the measurand. It can also be expressed as an estimate characterizing the range of values within which the true value of a measurand lies. When specifying the uncertainty of a measurement, it is necessary to indicate the principle on which the calculation has been made.
Verification is an investigation that shows that specified requirements are fulfilled.