According to ISO/IEC 17025 a laboratory may need to state compliance/conformity with a permitted limit for analytical results. Eurachem/CITAC has a Guide and a Leaflet from 2021 on compliance assessment focussing on decision rules. Here is a short presentation of the Guide.

ILAC has issued a revised ILAC G8 in 2019 to guide laboratories in choosing the decision rule. Here follow a short summary of the guide and the issue of compliance.

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Reporting of Compliance with Specification to Guidelines on Decision Rules and Statements of Conformity

In ISO/IEC 17025 as well as in ILAC G8 there is a reference to JCGM 106:2012 Evaluation of measurement data – The role of measurement uncertainty in conformity assessment. In the JCGM document from 2012 two different decision rules are presented

1) Decision rules based on simple acceptance (shared risk) (section 8.2) and

2) Decision rules based on guard bands (section 8.3).

This document provides: 
a) overall guidance on how to select appropriate decision rules; and 
b) guidance on compiling the required elements of a decision rule if no standard published rules apply. 

NOTE: Where further information is required regarding the mathematics of various decision rules covered in this document the reader is referred to the JCGM 106:2012.