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Mathematical Modelling and Data Analysis

Department 8.4

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Title: Analysis of Key Comparisons Incorporating Knowledge About Bias
Author(s): I. Lira, A. G. Chunovkina, C. Elster and W. Wöger
Journal: IEEE Transactions on Instrumentation and Measurement
Year: 2012
Volume: 61
Issue: 8
Pages: 2079--2084
DOI: 10.1109/TIM.2012.2193690
ISSN: 0018-9456
Web URL: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6189781
Keywords: Atmospheric measurements,Bayesian methods,Bismuth,Gaussian distribution,Laboratories,Measurement uncertainty,Particle measurements,Systematics,Uncertainty,laboratory bias estimation,measurement errors,measurement uncertainty,performance evaluation,statistical analysis,systematic effect,vanishing bias estimation
Tags: 8.42,KC
Abstract: A method is proposed for analyzing key comparison data. It is based on the assumption that each laboratory participating in the comparison exercise obtains independent and consistent estimates of the measurand and that, in addition, each laboratory provides an estimate of the quantity that collects all systematic effects that the laboratory took into account. The unknown value of the latter quantity, subtracted from its estimate, is defined as the laboratory's bias. The uncertainties associated with the estimates of the measurand and with the vanishing biases' estimates are also assumed to be reported. In this paper, we show that the information provided in this way may be of help for judging the performances of the laboratories in their correction of systematic effects. This is done by developing formulas for the final (consensus) estimates and uncertainties of the measurand and of the biases. Formulas for the final estimates and uncertainties of the pairwise differences between the biases are also developed. An example involving simulated key comparison data makes apparent the benefits of the proposed approach.

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