Calibration certificate red flags
No uncertainty, no k, no traceability statement, 'pass' without a decision rule, a range you did not ask for, or an accreditation symbol missing where one was promised — each is a reason to query.
- No measurement uncertainty, or one without a coverage factor.
- Uncertainty smaller than the laboratory's published CMC.
- A pass/fail statement with no decision rule.
- 'Traceable to national standards' with no identification of the standards used or their certificates.
- No environmental conditions stated.
- Calibration points that do not bracket your use range.
- Only as-left data after an adjustment.
- A certificate date after the instrument was back in your hands.
- The laboratory's accreditation symbol absent when accredited calibration was ordered.
- Values reported with more decimals than the instrument's resolution supports.
None of these is necessarily fraud; most are omissions. All of them make the certificate weaker evidence than it should be, and all are fixable by asking.
Frequently asked questions
- Can I ask a laboratory to reissue a certificate?
- Yes. Under ISO/IEC 17025 clause 7.8.8, amended certificates must be clearly identified as such and reference the original.
References
- [1]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
- [2]ILAC-P14: ILAC Policy for Measurement Uncertainty in Calibration
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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