The issue was first discussed in an exchange of experience workshop in December 2020 when the SEE NABs expressed their need for further guidance on how to understand the use of decision rules by CABs when declaring statements of conformity to a specification.
The training was provided by Ursula Ellenbeck from DAkkS and Ioannis Sitaras from ESYD and moderated by Rózsa Ring. It was attended by 39 participants from 5 SEE countries (Albania, Bonia and Herzegovina, Kosovo, Montenegro and North Macedonia).
Ursula Ellenbeck presented the ILAC-G8:09/2019 Guidelines on Decision Rules and Statement of Conformity which provides the internationally harmonized interpretation of the relevant clauses of ISO/IEC 17025:2017, then she introduced the concept of the guard bands and the types of the decision rules, focused on the binary decision rule with and without guard bands, presented what a laboratory should do when the customer does not wish a statement of conformity from the laboratory, and highlighted that the decision rules would ideally be included in the legislations or standards but due to lack of it, the laboratory has to agree on it with the customer.
Ioannis Sitaras first presented the 3 dimensions of the decision rules concept: (i) technical understanding, (ii) associated risk and (iii) socio-economic environment where the conformity assessment service is provided. Then he showed 5 cases studies and finally recommended some useful documents to read. The case studies focused on when the decision rule was defined by a legislation, the problems of compliance testing for official control of pharmaceutical products, a test scenario in which a customer asks a laboratory to ignore uncertainty, another case when the test standard does not mention measurement uncertainty and four test reports of a food product and statement of conformity were analyzed when the associated risk to customers, the decision rules and measurement uncertainty were different.
In the lively discussion, the participants raised several questions related to the case studies and discussed what the NAB should do when laboratories have different decision rules for the same product and when the laboratory declares an extremely high measurement uncertainty.
The feedback of the participants was very positive, they found the virtual training useful especially for the technical assessors.