NIST has developed an organizational policy on traceability and a set of related supplementary materials, which includes answers to questions frequently asked by customers of NIST measurement services. The policy and supplementary materials are intended to serve as a resource for NIST customers.
The mission of NIST is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life. To help meet the measurement and standards needs of U.S. industry and the nation, NIST provides calibrations, standard reference materials, standard reference data, test methods, proficiency evaluation materials1, measurement quality assurance programs, and laboratory accreditation services that assist a customer in establishing traceability of measurement results.
Metrological traceability requires the establishment of an unbroken chain of calibrations to specified references. NIST assures the traceability of measurement results that NIST itself provides, either directly or through an official NIST program or collaboration. Other organizations are responsible for establishing the traceability of their own results to those of NIST or other specified references. NIST has adopted this policy statement to document the NIST role with respect to traceability.
Statement of Policy
To support the conduct of its mission and to ensure that the use of its name, products, and services is consistent with its authority and responsibility, NIST adopts for its own use and recommends for use by others the definition of metrological traceability2 provided in the most recent version of the International Vocabulary of Metrology: "property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty." (International Vocabulary of Metrology - Basic and General concepts and Associated Terms (VIM), definition 2.41, see Reference ).
To support the conduct of its mission and to ensure that the use of its name, products, and services is consistent with its authority and responsibility, NIST:
- Adopts for its own use and recommends for use by others the definition of traceability provided in the most recent version of the International vocabulary of metrology - Basic and general concepts and associated terms (VIM): "property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.." .
- Establishes metrological traceability of the results of its own measurements and of results provided to customers in NIST calibration and measurement certificates, operating in accordance with the NIST Quality System for Measurement Services.
- Asserts that providing support for a claim of metrological traceability of the result of a measurement is the responsibility of the provider of that result, whether that provider is NIST or another organization; and that assessing the validity of such a claim is the responsibility of the user of that result.
- Communicates, especially where claims expressing or implying the contrary are made, that NIST does not define, specify, assure, or certify metrological traceability of the results of measurements except those that NIST itself provides, either directly or through an official NIST program or collaboration.
- Collaborates on development of standard definitions, interpretations, and recommended practices with organizations that have authority and responsibility for variously defining, specifying, assuring, or certifying metrological traceability.
- Develops and disseminates technical information on traceability and conducts coordinated outreach programs on issues of traceability and related requirements.
- Assigns responsibility for oversight of implementation of the NIST policy on metrological traceability to the NIST Measurement Services Advisory Group (MSAG).
2 The full term, "metrological traceability" is preferred when there is a risk of confusion with other meanings of the abbreviated term "traceability", which is sometimes used to refer to the "history" or "trace" of an item. The abbreviated term is also used in this document to improve readability, since it is clear that "metrological traceability" is meant in every case.