ISO 13528:2015

ISO 13528:2015 provides detailed descriptions of statistical methods for proficiency testing providers to use to design proficiency testing schemes and to analyse the data obtained from those schemes. It provides recommendations on the interpretation of proficiency testing data by participants in such schemes and by accreditation bodies.
The procedures in ISO 13528:2015 can be applied to demonstrate that the measurement results obtained by laboratories, inspection bodies, and individuals meet specified criteria for acceptable performance.
ISO 13528:2015 is applicable to proficiency testing where the results reported are either quantitative measurements or qualitative observations on test items.