In order to decide whether a result indicates compliance or non-compliance with a specification, it is necessary to take into account a decision rule that may include the measurement uncertainty associated with the result. A Eurachem guide provides guidance on how uncertainty may be taken into account in deciding compliance with a limit. A short Eurachem leaflet describes in short this guide.

ISO/IEC 17025 states the importance of a decision rule - 7.1.3 When the customer requests a statement of conformity to a specification or standard for the test or calibration (e.g. pass/fail, in-tolerance/out-of-tolerance), the specification or standard and the decision rule shall be clearly defined...


A guard band (g), a decision limit and an acceptance and a rejection zone based on an upper limit specification and a decision rule stating a high confidence of correct acceptance