Measurement uncertainty: requirements set in the accreditation standards

Measurement uncertainty is of high importance to all testing and calibration laboratories and those involved in sampling activities. Its evaluation requires good understanding of the method implemented and realisation of all factors contributing to it. It is required that the users of the results fully understand the meaning of uncertainty stated on test reports and calibration certificates and, when needed, ask for clarifications. Laboratories, both the accredited ones and those being prepared towards their accreditation, need to take this into account when evaluating the uncertainty of their results. Competent authorities need to consider the stated uncertainty to compare the result with a legislative limit. The producer can decide on adjustments needed. The consumer may find it more difficult to understand how this “uncertain component” of the results could affect their health, safety or economic rights. This article describes the relevant requirements of the accreditation standards referring both to testing and calibration laboratories and to proficiency testing and reference material producers. Further to this, the article explains why all these factors have to be considered by a laboratory.