ABSTRACT
The concept of traceability to national measurement standards has evolved considerably over the past 25 to 30 years. The 1980 paper Traceability: An Evolving Concept, by Brian Belanger, is often cited by other authors writing on this subject. This paper and others by National Bureau of Standards (NBS)/National Institute of Standards and Technology (NIST) authors have shown why the concept of traceability is not meaningful unless it incorporates quantified measurement uncertainty. Traditionally, measurement traceability has been described as an unbroken chain of comparisons to a primary or reference standard as maintained by a national measurement institute (NMI)—NIST or its counterpart institutions in other countries. During the 1970s, many organizations asked NBS for advice on how to comply with traceability requirements, since these requirements usually included language to have measurements "traceable to NBS."
