Evaluation of the uncertainty of the degree of equivalence

Some formulae used for evaluation of the uncertainties of the degree of equivalence between laboratories participating in an international comparison of activity measurement are presented. Two approaches are considered using two different estimators for the key comparison reference value: the arithmetic mean and the weighted mean. For each approach, four cases which can be encountered when dealing with comparison data are detailed. Finally, the effect of the uncertainties on the weights used in the second approach is also considered. This work has been developed for analysis of results of comparisons organized in the field of ionizing radiations, but the formulae are sufficiently general to allow their use for other comparisons. However, correlations between results have not been considered.