Uncertainty evaluation in normalization of isotope delta measurement results against international reference materials
Isotope delta measurements are normalized against international reference standards. Although multi-point normalization is becoming a standard practice, the existing uncertainty evaluation practices are either undocumented or are incomplete. For multi-point normalization, we present errors-in-variables regression models for explicit accounting of the measurement uncertainty of the international standards along with the uncertainty that is attributed to their assigned values. This manuscript presents framework to account for the uncertainty that arises due to a small number of replicate measurements and discusses multi-laboratory data reduction while accounting for inevitable correlations between the laboratories due to the use of identical reference materials for calibration. Both frequentist and Bayesian methods of uncertainty analysis are discussed.
KeywordsIsotope delta Normalization Uncertainty evaluation Random effects model
The authors have benefited from discussions with Blaza Toman, National Institute of Standards and Technology, USA.
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Conflict of interests
The authors declare that they have no conflict of interest.
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