National Physical Laboratory

Decision-making and conformity assessment

Conformity assessment is defined as any activity undertaken to determine, directly or indirectly, whether a product, process, system, person or body meets relevant standards and fulfils specified requirements. Guidelines that describe how to carry out conformity assessment that takes appropriate account of measurement uncertainty, e.g. in inspection processes using calibrated measuring systems) are set out in the JCGM 106 document (Joint Council for Guides in Metrology: Evaluation of measurement data - The role of measurement uncertainty in conformity assessment).

Decisions of conformity are currently made in many important application areas without a clear and harmonised basis for sharing the risks that arise from measurement uncertainty between the consumer and the supplier. For example, suppose that a consumer wishes to buy a specific quantity of goods (e.g. 10 litres of fuel, 5 kilogrammes of potatoes). The consumer wants to be sure that she receives no less than the required amount and the supplier wants to be sure that no more than the required amount is delivered. If they both use their own measuring systems and the systems have different measurement uncertainties they may disagree about how much has been delivered and consequently about how much should be paid. There are no generally agreed guidelines that assist in defining how the risks associated with under- or over-delivery should be shared. NPL's mathematicians are taking part in a pioneering European collaborative project to develop methods that address this need and help extend good practice in conformity assessment to new application areas. More information about the project.

Last Updated: 8 Apr 2014
Created: 5 Mar 2008