Analysis of Different Assigned Value Determination Methods on Gauge Block Calibration Proficiency Testing

Abstract

According to ISO/IEC 17043:2010, the definition of proficiency testing is evaluation of participant performance against pre-established criteria by means of interlaboratory comparisons. Thus pre-established criteria has significant impact on the evaluation of participant performance, in which assigned value attributed to a particular property of a proficiency test item and its standard deviation for proficiency assessment played the key role in the evaluation criteria. In order to understand the gauge block calibration capacity of the domestic laboratories in Taiwan, the Center for Measurement Standards / Industrial Technology Research Institute (CMS/ITRI) held and completed a gauge block calibration proficiency testing in 2016. In this proficiency testing, CMS used the calibration results from National Measurement Laboratory (NML) to determine the assigned value and its expanded uncertainty which were used to calculate the |En| values. In addition, according to ISO/IEC 13528:2015, the assigned value and its standard uncertainty can be determined according to the type and purpose of the proficiency testing scheme, including using the results from one laboratory, consensus values from participant results, etc. In order to explore the impact of choosing different methods to determine the assigned value and its expanded uncertainty for proficiency testing results, CMS recalculated the |En| values by using different assigned value determination method after the end of this proficiency testing. Thus, the narrative of this paper contains not only results of this gauge block calibration proficiency testing but also results of using different assigned value determination method to recalculate participant performance statistics.