Determination of a reference value, associated standard uncertainty and degrees of equivalence for CCRI(II) key comparison data

CCRI(II) key comparison data consist of a measured value of activity concentration, independently obtained, and the associated standard uncertainty for each laboratory participating in a key comparison. A method is proposed for calculating a key comparison reference value (KCRV), its associated standard uncertainty, and degrees of equivalence (DoE) for the laboratories. The estimator has the property that for increasingly discrepant data sets there is a smooth transition of the KCRV from the weighted mean to the arithmetic mean. It is a good compromise between efficiency and robustness, while providing also a reliable uncertainty. A suitable statistical criterion is provided to identify extreme data.. As the Commission’s in-house science service, the Joint Research Centre’s mission is to provide EU policies with independent, evidence-based scientific and technical support throughout the whole policy cycle. Working in close cooperation with policy Directorates-General, the JRC addresses key societal challenges while stimulating innovation through developing new standards, methods and tools, and sharing and transferring its know-how to the Member States and international community. Key policy areas include: environment and climate change; energy and transport; agriculture and food security; health and consumer protection; information society and digital agenda; safety and security including nuclear; all supported through a cross-cutting and multi-disciplinary approach. L A -N A -2 5 3 5 5 -E N -N