by James G. Salsbury
When an accredited laboratory makes a statement of conformity to a specification, ISO/IEC 17025 requires the use of a decision rule that takes into account the level of risk associated with the decision rule employed. There are numerous resources available that address the calculation of the likelihood of risks like false accept and false reject in measurement. However, level of risk is defined as the combination of the likelihood of risk along with the consequences of risk, and the consequences of risk in measurement decision rules is a rather unexplored area in existing literature. This paper specifically explores calibration of measuring instruments, which is a rather unique type of measurement, as calibration always supports subsequent downstream measurements made with the calibrated measuring instrument. This uniqueness provides an opportunity to explore the consequences of decision rules used in calibrations that involve statements of conformity. This paper explores the impact of risk and decision rules in calibration and shows how it is possible, and potentially more useful, to account for the level of risk associated with decision rules by managing the consequences and not necessarily the likelihood of the risk.
