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Cited by 36Scientific Measurement and Uncertainty EvaluationAdvanced Measurement and Metrology TechniquesCalibration and Measurement Techniques

Combined result and associated uncertainty from interlaboratory evaluations based on the ISO Guide

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Kacker, R, Datla, R, Parr, A·2002·Metrologia
DOI 10.1088/0026-1394/39/3/5
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Abstract

We address the problem of determining the combined result and its associated uncertainty in the measurement of a common measurand by a group of competent laboratories. Most data analyses of interlaboratory evaluations are based on the assumption that the expected values of the individual laboratory results are all equal to the value of the common measurand. This means that the laboratory results are subject to random effects only with respect to the value of the measurand. This assumption is frequently unjustified. We use the more realistic assumption that the laboratory results are subject to both random and systematic effects with respect to the value of the measurand. In this case, the value of the measurand may fall anywhere within the range of results. Therefore, a combined result and its associated standard uncertainty that place a non-negligible fraction of the results outside the 2-standard-uncertainty interval are unsatisfactory representations of the value of the common measurand provided by the set of laboratory results. The more realistic assumption requires us to deal with the uncertainty arising from possible systematic effects in the laboratory results. Following the approach of the ISO Guide to deal with systematic effects, we propose a three-step method to determine a combined result and its associated standard uncertainty such that the 2-standard-uncertainty interval would include a sufficiently large fraction of the results. When the interlaboratory evaluation is an International Committee for Weights and Measures (CIPM) key comparison, we suggest that the combined result and its associated standard uncertainty determined by the three-step method be identified with the key comparison reference value and its associated standard uncertainty. These quantities can then be used to specify the degree of equivalence of the individual laboratory results. We illustrate the three-step method by applying it to the results of an international comparison of cryogenic radiometers recently organized by the Consultative Committee for Photometry and Radiometry (CCPR).

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  • With the lock scheme to the transitions from the mF=±9/2 states, online information on the magnetic field strength at the position of the atoms is obtained provided that the lattice vector shift is sufficiently small.

    “With the lock scheme to the transitions from the m F = ± 9 / 2 states, we obtain online information on the magnetic field strength at the position of the atoms provided that the lattice vector shift [48] is sufficiently small.”

    From Long-distance chronometric leveling with a portable optical clock (2024) · cites this paper as [48]

    The citation is attached to the condition about a sufficiently small lattice vector shift. Our copy’s section 5 discusses comparisons of cryogenic radiometers, not lattice vector shifts or atomic transitions. Searches for those terms and related optical-lattice terminology found no passage addressing the cited condition. (LLM, conf=0.78)

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Authors
Kacker, R., Datla, R., & Parr, A.
Affiliations
National Institute of Standards and Technology (US)
ORCID
Venue
Metrologia
Publisher
IOP Publishing
Published
2002-06
Volume
39
Issue
3
Pages
279-293
ISSN
0026-1394 (ISSN-L)
DOI
10.1088/0026-1394/39/3/5
OpenAlex
W2031377355
Cited by
36
References
16
Citations by year
2025: 1 · 2024: 1 · 2018: 1 · 2017: 5 · 2016: 3 · 2015: 2 · 2014: 1 · 2013: 1 · 2012: 3
FWCI
2.63
Type
journal article
Language
en
Open access
Locations
Metrologia (publishedVersion)
Funders
Advanced Low Carbon Technology Research and Development Program
Topics
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Scientific Measurement and Uncertainty Evaluation
  • Physical Sciences › Engineering › Mechanical Engineering › Advanced Measurement and Metrology Techniques
  • Physical Sciences › Engineering › Aerospace Engineering › Calibration and Measurement Techniques
Keywords
interlaboratory comparison, measurement uncertainty, systematic effects, random effects, key comparison, cryogenic radiometer, reference values

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