ENBIS-16 in Sheffield

11 – 15 September 2016; Sheffield Abstract submission: 20 March – 4 July 2016

Reassessment of Calibration and Measurement Capabilities based on Key Comparison Results

12 September 2016, 11:30 – 11:50

Abstract

Submitted by
Katsuhiro Shirono
Authors
Katsuhiro Shirono (National Institute of Advanced Industrial Science and Technology), Maurice Cox (National Physical Laboratory)
Abstract
The uncertainty of a calibration and measurement capability (CMC) is the expanded measurement uncertainty available to customers under normal conditions of measurement. We consider CMCs for which there is a supporting key comparison (KC), that is, where the KC and the CMCs relate to the same or closely similar measurands. When laboratories have performed unsatisfactorily in a KC, such laboratories may be required to set new values for their CMC uncertainties. These new values are set following a review process supervised by the appropriate working group in the relevant Consultative Committee of the CIPM. Although the review process supports the reassessment of the CMC uncertainties from a practical perspective, it is not generally carried out on a statistical basis.
We consider statistical methods to determine appropriate values for CMC uncertainties in such cases. In this study, an extension of several existing methods for analysing KC data are applied for this purpose, and a new method in which Bayesian statistics are employed is proposed. It is found that some of the methods provide CMC uncertainties that reasonably relate to the degrees of equivalence of the KC results. These methods could be acceptable to reassess CMC uncertainties through a supporting KC.
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