Assessment of conformity, decision rules and risk analysis

Abstract

Measurement uncertainty has important economic consequences for calibration and inspection activities. In calibration reports, the magnitude of the uncertainty is often taken as an indication of the quality of the laboratory. In industrial measurements, uncertainty has an economic impact through the decision rule employed in accepting and rejecting products. With significant economic interests at stake, manufacturers and consumers have to guard against accepting bad products and rejecting good ones. While the evaluation of measurement uncertainty is a pure technical activity well described in the GUM, the selection of a decision rule is a business decision that involves cost considerations. Recently, several national and international standards bodies have addressed the decision rule issue to provide a uniform, unambiguous terminology for documenting a decision rule and to describe the relationship between conforming characteristics and acceptable measurement results. Similarly, the issue of risk analysis addresses the problem of determining the gauging limits that define the boundaries of acceptable measurement results. Gauging limits are chosen to balance the risks of the two types of decision errors (accepting nonconforming products and rejecting conforming products), whose relative magnitudes depend upon product-specific economic factors. This paper reviews recent standardization developments in these areas. © 2014 Oldenbourg Wissenschaftsverlag GmbH, Ein Unternehmen von De Gruyter GmbH, Berlin/Boston.