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Contact
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Will
Guthrie
Statistical Engineering
Division
Information Technology
Laboratory
301-975-2854
william.guthrie@nist.gov
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Impetus/How Project Began
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Interlaboratory studies have long been used to ensure measurement
capability for commerce since accurate measurements are necessary
for assessing product specifications. For this reason design and
analysis of interlaboratory studies have been an important part of
the ITL Statistical Engineering Division's (ITL/SED) work for many
years. Recently, however, a new type of interlaboratory study,
known as a key comparison, has taken a critical new place in the NIST
mission. In the last year, key comparisons, international
interlaboratory studies for comparing measurement results between
leading National Metrology Institutes (NMI's), have provided many new
opportunities for ITL/SED to collaborate with scientists across NIST.
The impetus for these new opportunities is a Mutual Recognition
Arrangement (MRA) signed by the NMI's belonging to the International
Committee for Weights and Measures (CIPM) "to establish the degree
of equivalence of national measurement standards maintained by NMI's,
to provide for the mutual recognition of calibration and
measurement certificates issued by NMI's, [and] thereby to provide
governments and other parties with a secure technical foundation for
wider agreements related to international trade, commerce and
regulatory affairs."
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Objective(s)
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Key comparisons serve as the technical basis for the MRA and must
therefore accurately reflect the true relationships between
measurement systems maintained by NMI's belonging to the CIPM. The
results of key comparisons must also be extensible to members of
Regional Metrology Organizations (RMO's) to maximize recognition of
measurement capabilities that exist in other metrology laboratories
around the world.
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Staffing Profile and Funding
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FTE = 1.0 (Mathematical Statistician)
Funding is for $220K STRS.
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Timeline/
Milestones
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The timelines and milestones for this project are:
- FY97 - MRA in development, key comparison planning and data
collection initiated.
- FY98 - MRA in development, key comparison planning and data
collection/reporting.
- FY99 - MRA in development, key comparison planning and data
collection/reporting .
- FY99 - Analysis of key comparison data started, draft reports
written and circulated.
- FY00 - MRA signed by National Metrology Institutes belonging to
the CIPM.
- FY00 - Analysis of key comparison data, draft reports written
and circulated.
- FY00 - Planning and experiment design started for additional
key comparisons.
- FY00 - Publication of final reports for first key comparisons.
- FY01 - Analysis of key comparison data, preparation of
associated reports.
- FY01 - Publication of final reports for additional key
comparisons.
- FY01 - Key comparisons to begin for other measurement methods.
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NIST Involvement
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The following NIST staff are involved in this project:
- J. J. Filliben (Division 898, ITL),
- Will Guthrie (Division 898, ITL),
- Raghu Kacker (Division 898, ITL),
- Stefan Leigh (Division 898, ITL),
- Mark Levenson (Division 898, ITL),
- Walter Liggett (Division 898, ITL),
- Jack Wang (Division 898, ITL),
- NIST scientists from BFRL, CSTL, EEEL, MEL, MSEL, and PL.
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Outside Involvement
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The following outside organizations have been involved in this
project: NMI's and Regional Metrology Organizations (RMO's) from
Argentina, Australia, Brazil, Canada, China, Denmark, France,
Germany, India, Italy, Japan, Korea, Mexico, Netherlands, Poland,
Russia, Slovakia, the United Kingdom, the United States, and
New Zealand along with RMO's from most countries in North and
South America and some Caribbean countries.
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What Work Has ITL Done
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ITL/SED contributions to interlaboratory studies and key
comparisons include the following.
- Performed data analyses which account for covariances in
the measurements used to compute differences in results
between labs and which ensure that uncertainties have a
confidence level of 95%, as outlined in MRA policies.
- Contributed in the computation of reference values from
interlaboratory data. Reference values are a sometimes
controversial part of the MRA whose real role is still
currently being worked out at both the policy and technical
levels. The earliest key comparisons, those analyzed to date,
have often used designs which allow for straight-forward
computation of the necessary measurement differences but give
less consideration to computation of uncertainties. Based on
contacts from current work, however, ITL/SED has recently
begun to contribute to comparison designs, ensuring that data
collection will be as effective as possible. Opportunities
to impact the design and analysis of comparisons have also
been bolstered by participation in international meetings on
interlaboratory studies organized by statisticians and other
researchers from NMI's.
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What Work Has Been Done By Collaborators
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The contributions of collaborators include the following.
- Design of comparison studies.
- Coordination with BIPM and comparison participants.
- Data collection.
- Dissemination of Key Comparison results.
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What Developments Have Occurred and How Has the Project Changed
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Nothing to report at this time.
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Publications or Artifacts
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This project has generated the following publications.
The Comite Consultatif or other sponsor of each Key Comparison will
publish a full report on each comparison. The results of each
comparison will also be available in the BIPM Key Comparison
Database at
- http://www.bipm.fr/enus/8_Key_Comparisons/database.html
(English) and
- http://www.bipm.fr/fra/8_Key_Comparisons/database.html
(French).
Summaries of each report will also be published in Metrologia.
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How Industries Have Benefited From NIST's Work
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Customers of key comparisons include NMI's in the CIPM and the
various RMO's, secondary government and commercial metrology
laboratories, and end-users of secondary metrology labs' services.
The success of the MRA, based on successful key comparisons, will
reduce measurement-based barriers to international trade by promoting
convergence of measurement techniques. Assessment and discussion of
measurement capabilities in an open forum may encourage NMI's to
improve absolute measurement capabilities as well.
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Acknowledgements of the ITL's Effort
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Acknowledgements of ITL's efforts in the design and analysis of key
comparisons include co-authorship and formal acknowledgment in official
Key Comparison reports.
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Future Related Activities
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The recent signing (October, 1999) of the MRA has led to a large
increase in the number of interlaboratory studies that ITL/SED is
involved in. The fact that international recognition of measurement
services that the NMI's offer is directly supported by regular
participation in relevant key comparisons suggests that this area
will be an increasingly important source of ITL activity for some
time. As more key comparisons are finished there is likely to be a
need for ITL/SED to answer questions about the linkages between key
comparisons and the measurement services that they are designed to
support.
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Additional Information
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There are no links to additional information at this time.
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