Analysis of Key Comparison Data: Unstable Travelling Standards

Authors: Elster, C.¹; Woger, W.²; Cox, M.³

Source: Measurement Techniques, Volume 48, Number 9, September 2005 , pp. 883-893(11)

Publisher: Springer

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Abstract:

A procedure for the analysis of key comparison data is proposed in the case where the travelling standard shows a deterministic or random drift. It is assumed that some parametric model such as a linear trend is appropriate for modelling the deterministic part of the drift. The random part of the drift is assumed to be adequately described by a random walk model. The chosen drift model is determined by least squares and a model check is carried out. If the model check is satisfied, the derived drift model is applied to determine degrees of equivalence. A star-type sequence is required for the comparison in order to check the adequacy of the random drift model. The procedure is illustrated by its application to simulated data.

Keywords: key comparison; stability; random walk; least squares

Document Type: Research article

DOI: 10.1007/s11018-005-0239-1

Affiliations: 1: Email: Clemens.Elster@ptb.de 2: Email: Wolfgang.Woeger@ptb.de 3: Email: Maurice.Cox@npl.co.uk