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  • Author or Editor: J. Dahlgran x
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Abstract  

Data from seven Mixed Analyte Performance Evaluation Program studies have been used to identify specific problems with results and/or laboratories. These data have never been used to determine the bias or variability in data reporting for these laboratories in general. These historical analytical data were analyzed for accuracy and precision overall and separated by method of sample preparation, method of sample pretreatment, method of detection and sample size. The calculated mean percent relative bias was analyzed for the actinides (241Am, 238Pu, 239/240Pu, 234/233U, and 238U) in the soil and water standards. Results from most analysis methods were at least slightly negatively biased. For the water standards, the overall 95% confidence interval for the mean percent relative bias was −1.6% to −0.5% indicating that the average actinide results slightly underestimated the true concentration. For the soil standards, the overall 95% confidence interval for the mean percent relative bias was −8.1% to −6.6% indicating that the average actinide results moderately underestimated the true concentration.

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Abstract  

Radioanalytical performance testing programs provide radioassay laboratories, regulators and the public performance-based evidence that measurement capabilities are in control. Performance acceptance criteria that combine aspects of measurements difference from a known value and the associated combined uncertainty establishes a quantitative statement of statistical confidence. However, there is need for a reasonable upper limit of the reported measurement uncertainty. Evaluation of thousands of historical U.S. DOE Mixed-Analyte Performance Evaluation Program measurement results for 17 radionuclides in soil and water samples provides predictive expectations for future measurement results and a statistical basis for establishing reasonable upper limits for reported measurement uncertainties for performance evaluation programs.

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