Frequently Asked Questions

What is metrology traceability?

A core concept in metrology is metrological traceability, defined in the International Vocabulary of Metrology – Basic and General Concepts and Associated Terms (VIM, 3rd edition, JCGM 200:2008) as “the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, all having stated uncertainties.” The level of traceability establishes the level of comparability of the measurement: whether the result of a measurement can be compared to the previous one, a measurement result a year ago, or to the result of a measurement performed anywhere else in the world.

Traceability is most often obtained by calibration, establishing the relation between the indication of a measuring instrument and the value of a measurement standard (the NMS). These standards can either be primary (Established through a realisation of the unit and the traceability is to the NMI) or secondary, where an artefact calibrated against a primary standard at another NMI is maintained as the NMS (and the traceability is to the NMI with the primary standard). In chemistry, traceability is mostly established through the use of certified reference materials to calibrate the measuring equipment.​  For further information, visit NMISA About Metrology