Statistical analysis of CIPM key comparisons based on the ISOGuide

An international Advisory Group on Uncertainties has published guidelines for the statistical analysis of a simple key comparison carried out by the Consultative Committees of the International Committee of Weights and Measures (CIPM) where a travelling standard of a stable value is circulated among the participants. We discuss several concerns regarding these guidelines. Then, we describe a statistical model based on the Guide to the Expression of Uncertainty in Measurement to establish the key comparison reference value, the degrees of equivalence, and their associated standard uncertainties on the basis of the data submitted by the participants. The proposed statistical model applies to all those CIPM key comparisons where the submitted results are mutually comparable and appropriate for determining the key comparison reference value and the submitted uncertainties are sufficiently reliable.