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Transfer Standard Uncertainty Can Cause Inconclusive Inter-Laboratory Comparisons



John D. Wright, Blaza Toman, Bodo Mickan, Gerd Wubbeler, Olha Bodnar, Clemens Elster


Inter-laboratory comparisons use the best available transfer standards to check the participants’ uncertainty analyses, identify underestimated uncertainty claims or unknown measurement biases, and improve the global measurement system. For some measurands (e.g., flow) instability of the transfer standard can lead to an inconclusive comparison result. If the transfer standard uncertainty is large relative to a participating laboratorys uncertainty, the commonly used standardized degree of equivalence |Eni|{less than or equal to}1 criterion (where Eni=di/2udi) does not always correctly assess whether a participant is working within their uncertainty claims. We show comparison results that demonstrate this issue and propose several criteria for assessing a comparison result as passing, failing, or inconclusive. We investigate the behavior of En and alternative comparison measures for a range of values of the transfer standard uncertainty relative to the individual laboratory uncertainty values. The proposed alternative criteria successfully discerned between passing, failing, and inconclusive comparison results for the cases we examined.


comparison, degree of equivalence, transfer standard uncertainty


Wright, J. , Toman, B. , Mickan, B. , Wubbeler, G. , Bodnar, O. and Elster, C. (2016), Transfer Standard Uncertainty Can Cause Inconclusive Inter-Laboratory Comparisons, Metrologia, [online], (Accessed April 18, 2024)
Created October 7, 2016, Updated February 19, 2017