Decision rule is defined as “a rule that describes how measurement
uncertainty will be accounted for when stating conformity with a specified
requirement”. (Clause 3.7 of ISO/IEC 17025:2017)
Decision Rule is a statement of rules explaining how measurement
uncertainty is used when performing conformity assessment.
Conformity Assessment is an activity to determine conformance to specifications using the decision rule. This is where we determine a pass of fail decision.
Decision rule requirements are mostly applicable to the customer since they are the ones who need to determine conformance to their instruments.
But in order for them to understand, the lab should make the effort to educate and help them decide what decision rule is best for them. This as a result will help the lab how to properly properly implement it. Since it is a requirement during conformity assessment, we cannot avoid it but more so, we need to understand it.