Analysis of a regional metrology organization key comparison: model-based unilateral degrees of equivalence

Abstract

Abstract A statistical testing method is developed to analyze a Regional Metrology Organization (RMO) key comparison (KC) with linking to the corresponding KC conducted by the International Committee of Weights and Measures (CIPM). We establish a statistical model to which a generalized least-squares method is applied to determine a linking invariant, ensuring that the CIPM KC reference value is unchanged by the analysis. The proposed method generally gives different unilateral and bilateral degrees of equivalence (DOEs) from those assessed by other methods. The approach accounts for uncertainty information provided by all participating laboratories and correlation information provided by the linking laboratories. Since decisions are made on the basis of calculated DOEs, we emphasize that it is valuable to have adequate knowledge of the properties of methods used for analyzing the results from an RMO KC.