quantity value used as a basis for comparison with values of quantities of the same kind.
Many different types of materials and devices may have a reference quantity value and an associated measurement uncertainty. Some examples are given below.
The quantity value given on the certificate of a certified reference material (CRM) with its associated measurement uncertainty is a reference quantity value for the particular property to which it relates.
The values of a set of solutions of known concentration, analysed to build a calibration diagram , are reference quantity values used for determining the value of the same quantity in other samples.
In a calibration laboratory, mercury-in-glass thermometers are calibrated against a measurement standard (thermometer) reproducing specific temperature values (with associated uncertainties): these are reference values of the quantity ‘temperature’.
Analysts use the value assigned to a CRM as a reference quantity value for the assessment of the trueness of a measurement procedure.
In order to assess the competence of staff and laboratories, the staff may be required to analyse samples which have assigned values. The value assigned to a sample may be a quantity value obtained either from previous analyses by more experienced staff/laboratories or from PT rounds, or from a certificate if the sample is a CRM. In this context, the value assigned to any of these materials is deemed to be a reference quantity value.
ref: Terminology in Analytica Measurement Introduction to VIM 3
