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The Fifth International Radiocarbon Intercomparison (VIRI): An Assessment of Laboratory Performance in Stage 3

Published online by Cambridge University Press:  18 July 2016

E Marian Scott*
Affiliation:
Department of Statistics, University of Glasgow, Glasgow G12 8QW, Scotland
Gordon T Cook
Affiliation:
SUERC, Scottish Enterprise Technology Park, East Kilbride G75 0QF, Scotland
Philip Naysmith
Affiliation:
SUERC, Scottish Enterprise Technology Park, East Kilbride G75 0QF, Scotland
*
Corresponding author. Email: [email protected]
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Abstract

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Proficiency testing is a widely used, international procedure common within the analytical chemistry community. A proficiency trial (which VIRI is) often follows a standard protocol, including analysis that is typically based on z-scores, with one key quantity, σp. From a laboratory intercomparison (sometimes called a proficiency trial), we hope to gain an assessment of accuracy (in this case, from dendro-dated samples), laboratory precision (from any duplicate samples), and generally, an overall measure of performance, including measurement variability and hence realistic estimates of uncertainty. In addition, given our stated aim of creating an archive of reference materials, we also gain a determination of consensus values for new reference materials.

VIRI samples have been chosen to deliver these objectives and the sample ages included in the different stages, by design, spanned modern to background. With regard to pretreatment, some samples required intensive pretreatment (e.g. bone), while others required none (e.g. cellulose and humic acid). Sample size was not optimized, and indeed some samples were provided solely for accelerator mass spectrometry (AMS) measurement. In this sense, VIRI presented a more challenging exercise than previous intercomparisons, since by its design in stages, one can explore improvements (or deteriorations) over time in laboratory performance. At each stage, more than 50 laboratories have participated, with an increasing demographic shift towards more AMS and fewer radiometric laboratories.

Type
Calibration, Data Analysis, and Statistical Methods
Copyright
Copyright © 2010 by the Arizona Board of Regents on behalf of the University of Arizona 

References

Scott, EM 2003. The Third International Radiocarbon Intercomparison (TIRI) and the Fourth International Radiocarbon Intercomparison (FIRI). Radiocarbon 45(2):135408.Google Scholar
Scott, EM, Cook, GT, Naysmith, P, Bryant, C, O'Donnell, D 2007. A report on Phase 1 of the 5th International Radiocarbon Intercomparison (VIRI). Radiocarbon 49(2):409–26.CrossRefGoogle Scholar
Scott, EM, Cook, GT, Naysmith, P. 2010. A report on phase 2 of the Fifth International Radiocarbon Intercomparison (VIRI). Radiocarbon 52(2–3):846–58.Google Scholar