Statistical aspects of proficiency testing in analytical laboratories. Part 3. Confirmatory statistical tests for scheme organisers

Abstract

An examination of the data produced in rounds of proficiency tests is important to the organisers of schemes in order to test for discrepancies between the actual outcome and the expected outcome. Such discrepancies, if present, would suggest that a valid interpretation of the results may not be possible or would need special consideration of the data. A series of tests that can be applied in standard statistical packages is proposed and illustrated with data from a proficiency test scheme.