[ RadSafe ] On interchangeability of two laboratories

Cary Renquist cary.renquist at ezag.com
Fri Jun 18 11:21:40 CDT 2010

Perhaps a bit esoteric, but might be of interest to some of ya...

On interchangeability of two laboratories 

FYI: Most papers from the IOP (including this one) are available for
free download for 30 days after publication.

    C M Wang and Hari K Iyer 2010 Metrologia 47 435

    doi: 10.1088/0026-1394/47/4/009


    This paper proposes a measure for assessing the equivalence between
the results of two laboratories. The measure is called asymmetric
interchangeability. It is asymmetric since, based on this measure, one
laboratory may be considered interchangeable with another laboratory but
the converse may not be true. Such a situation can arise when the
accuracy and precision of one laboratory are noticeably greater than
that of the other. The proposed measure of interchangeability depends on
the parameters of the measurement models, which include means, variances
and the correlation of the two laboratories being compared. Since the
level of correlation is often difficult to assess, it is assumed to be
zero in this paper. Fiducial procedures are presented for testing the
hypothesis that a laboratory is directionally interchangeable with
another. The procedure is based on comparing a probability measure,
which is shown to be closely related to asymmetric interchangeability,
with an agreed threshold. Computer programs for calculating the p-value
of the tests, written by use of open-source software, are listed.


Cary Renquist
Radiation Safety Officer
Manager, Health Physics
cary.renquist at ezag.com

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