Role of measurement uncertainty

The method used to decide whether an instrument conforms with the requirements for legal metrology has an important impact on the accuracy that can be subsequently achieved. There are two approaches to deciding on conformity, the classical approach that does not take uncertainty directly into account, and a more modern approach that is consistent with the industrial decision rules for proving conformity with specifications. On the basis of a consistent mathematical treatment, the consequences of using the different approaches are demonstrated, along with their influence on the uncertainty contribution of verified instruments that are being used.