Proficiency testing policy and plan :

This publication provides the policies and plans for the Proficiency Testing (PT) Program of the National Institute of Standards and Technology (NIST) Office of Weights and Measures (OWM). This OWM Proficiency Testing policy and plan has been updated to ensure compliance with the latest applicable documentary standards and policies of the International Laboratory Accreditation Cooperation (ILAC). The PT program has been in place since the early 1980s as a core part of the support to State weights and measures laboratories through regional measurement assurance programs. Original activities were conducted as “round robin” tests in support of ongoing measurement assurance activities related to support for state laws with requirements for metrological traceability to national and international standards. The 2026 edition was updated based on feedback from users and included review and associated updates based on the latest applicable policies of the ILAC, NIST Handbook 143, Recognition Program (2023), NIST Handbook 150, National Voluntary Laboratory Accreditation Program (NVLAP) Procedures and General Requirements (2020), and the latest available documentary standards for proficiency testing, including ISO/IEC 17043:2023, Conformity Assessment — General requirements for the competence of proficiency testing providers, and ISO 13528:2022, Third Edition, 2022-08, Statistical methods for use in proficiency testing by interlaboratory comparison.