Many measurements are made to provide an objective basis for decisions about a product or a process, for example compliance with a regulation related to environmental emissions, decisions as to whether or not a person is infected with a disease, assessment of compliance of a product with manufacturing tolerances or the water content in oil for legal metrology and fiscal purposes. The inevitable presence of measurement uncertainty leads to the risk of incorrect conformity decisions for consumers, suppliers and the public at large. There is therefore the need to make reliable decisions of conformity given relevant measurement results with associated uncertainty statements and to ensure the consistent application of decision-making techniques, in particular for multivariate cases, which are not currently addressed in guidelines and standards. One example of a multivariate case of conformity assessment is the decision as to whether a specimen meets its design, when this design is not described in terms of a single parameter, but in terms of several parameters (e.g. the several critical dimensions of periodic nanostructures).

For conformity assessment the state of the art is embodied in documents such as ISO 10576 and draft documents including GUM Supplement JCGM 106 and OIML documents. Guides such as those from EURACHEM are already widely used by major stakeholder groups. However, others such as OIML D 30: Guide for the application of ISO/IEC 17025 to the assessment of Testing Laboratories involved in legal metrology do not reflect modern developments in statistical methods.