Decision Rules and Statements of Conformity for Calibration Laboratories
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For any ISO/IEC 17025 accredited laboratory, understanding how to correctly issue statements of conformity is essential to reliable pass/fail reporting. A decision rule defines how measurement uncertainty is accounted for when making a conformity determination, and getting it wrong can have serious consequences, particularly in safety-critical industries. Whether you are a laboratory manager, quality engineer, or accreditation assessor, having a clear framework for conformity assessment protects both your customers and your accreditation status.
Morehouse Instrument Company has developed comprehensive guidance on statements of conformity and decision rules, drawing on ISO/IEC 17025:2017, ILAC-G8:09/2019, UKAS LAB 48, and JCGM 106:2012. This guidance addresses the most common points of confusion in the field, from guard band calculation and Test Uncertainty Ratio (TUR) to the critical difference between specific risk and global risk. Many laboratories unknowingly issue non-compliant certificates simply by stating "PASS" or "IN TOLERANCE" without identifying the decision rule applied or reporting expanded measurement uncertainty.
Issuing accurate statements of conformity starts with choosing the right decision rule for your application, whether that is simple acceptance, specific risk guard banding, or managed guard bands, and communicating that choice to your customer before measurements are taken. Our guidance document walks through each method with worked examples, real-world scenarios, and a practical compliance checklist. Download it today and ensure your laboratory's statements of conformity mean exactly what they say.
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