Coverage intervals according to MARLAP, Bayesian statistics and the new ISO 11929 for ionising radiation measurements

Abstract

The coverage intervals stipulated by ISO 11929 (2010) for estimating the uncertainty from ionising radiation measurements of replicate samples are compared with those of MARLAP (=Multi-Agency Radiological Laboratory Analytical Protocols Manual) and of Bayesian statistics. The latter two intervals agree well despite their different concepts. Whereas for either of them the ratio of the length of the coverage interval and MARLAP's standard uncertainty grows when the number of samples decreases, no such growth arises for the interval mandated by ISO 11929 (2010). It may therefore be too short (e.g. for three samples by a factor of approximately 2).