Evaluating systematic differences between laboratories in interlaboratory comparisons. http://dx.doi.org/10.1007/s11018-009-9340-1

Abstract

A Bayesian analysis of the data from interlaboratory comparisons involving a single stable traveling standard is presented. The approach is based on the assumption that each participating laboratory provides an estimate of the value of the measurand with zero estimated bias. In addition, it is assumed that each of the reported uncertainties is given in the form of two separate components, one associated with random effects and the other associated with systematic effects. It is finally assumed that all information is consistent. Using Gaussian probability density functions, simple formulas for the joint estimate of the value of the measurand and for the a posteriori estimates of the biases and of their differences are derived. Formulas for the uncertainties of all these estimates are also given.