title: Transfer Standard Uncertainty Can Cause Inconclusive Inter-Laboratory Comparisons.
abstract: 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, instability of the transfer standard can lead to an inconclusive comparison result. If the transfer standard uncertainty is large relative to a participating laboratory's uncertainty, the commonly used standardized degree of equivalence ≤ 1 criterion 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 the standardized degree of equivalence 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.
authors.affiliation: National Institute of Standards and Technology (NIST).
authors.forename: John
authors.initials: J
authors.lastname: Wright
authors.affiliation: National Institute of Standards and Technology (NIST).
authors.forename: Blaza
authors.initials: B
authors.lastname: Toman
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB).
authors.forename: Bodo
authors.initials: B
authors.lastname: Mickan
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB).
authors.forename: Gerd
authors.initials: G
authors.lastname: Wübbeler
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB).
authors.forename: Olha
authors.initials: O
authors.lastname: Bodnar
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB).
authors.forename: Clemens
authors.initials: C
authors.lastname: Elster