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Laboratory Effects Models for Interlaboratory Comparisons



Blaza Toman, Antonio M. Possolo


Statistical analysis of inter-laboratory comparisons (e.g. Key Comparisons, Supplemental Comparisons) is required to produce an estimate of the measurand called a reference value and further, measures of equivalence of the participating laboratories. Methods of estimation of the reference value have been proposed that rest on the idea of finding a so-called consistent subset of laboratories, that is, eliminating outlying participants. In this paper we propose an alternative statistical model, one that accommodates all of the participants’ data and incorporates the dispersion among the laboratories into the total uncertainty of the various estimates. This model recognizes the fact that the dispersion of values between laboratories often is substantially larger than the measurement uncertainties provided by the participating laboratories. We illustrate the method on data from key comparison CCQM-K25.
Accreditation and Quality Assurance


Statistical analysis, key comparisons, reference value, uncertainty.


Toman, B. and Possolo, A. (2009), Laboratory Effects Models for Interlaboratory Comparisons, Accreditation and Quality Assurance (Accessed April 17, 2024)
Created June 16, 2009, Updated February 19, 2017