A new approach for proficiency test exercise data evaluation

In this paper, a new data evaluation method for proficiency test exercises consisting of a combination of a z -test, a zeta test and an uncertainty outlier test is presented. This new method is compared with eight other evaluation methods (both measurement uncertainty using and measurement uncertainty ignoring) in common use and/or recommended by ISO 13528. The data set used to test the evaluation methods is real data and consists of the 95 Nb results of the National Physical Laboratory Environmental Radioactivity Proficiency Test Exercise 2007. The evaluation of 14 out of 32 results were affected by the choice of method.