Reporting results and statements of conformity (clause 7.8)
A certificate must carry defined identification, method, traceability and uncertainty information — and any pass/fail statement must name the decision rule.
Clause 7.8 sets out the required content of reports and certificates. For calibrations it adds the measurement uncertainty presented in the same unit as the measurand or relative to it, the conditions under which the calibration was made, a statement of metrological traceability, and results before and after any adjustment or repair.
Decision rules
Where a statement of conformity to a specification is made, the laboratory must document the decision rule employed and take account of the risk associated with it — false accept and false reject — and apply it as agreed with the customer. ILAC-G8 describes common rules: simple acceptance (uncertainty ignored, shared risk), guard banding (acceptance limits narrowed by the uncertainty or a fraction of it), and non-binary statements such as 'conditional pass'.
Frequently asked questions
- What if the customer does not specify a decision rule?
- The laboratory must choose one, document it and state it on the certificate. Silence is not an option under the 2017 edition.
- Can a certificate say 'within tolerance' without an uncertainty?
- Not on an accredited certificate: the uncertainty must be reported, and the decision rule must show how it was accounted for.
References
- [1]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
- [2]ILAC-G8: Guidelines on Decision Rules and Statements of Conformity
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
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