Standards for Measurement Uncertainty

Measurement uncertainty has important economic consequences for calibration and measurement activities. In calibration reports, the magnitude of the uncertainty is often taken as an indication of the quality of the laboratory, and smaller uncertainty values generally are of higher value and of higher cost. Accredited measurement laboratories and even some industrial measurements are evaluating measurement uncertainty, employing decision rules, performing risk analysis, and asserting measurement traceability. The Dimensional Metrology Group (683.01) is actively involved in the ASME B89.7 and the ISO TC213 WG4 committees on measurement uncertainty. The following U.S. documents provide information and assistance regarding measurement uncertainty and are available at www.asme.org.

	ASME B89.7.3.1-2001, Guidelines to Decision Rules in Determining Conformance to Specifications — addresses the role of measurement uncertainty when accepting or rejecting products based on a measurement result and a product specification.
	ASME B89.7.3.2-2007, Guidelines for the Evaluation of Dimensional Measurement Uncertainty — provides a simplified approach to the evaluation of dimensional measurement uncertainty.
	ASME B89.7.3.3-2002, Guidelines For Assessing the Reliability of Dimensional Measurement Uncertainty Statements — examines how to resolve disagreements over the magnitude of the measurement uncertainty statement.
	ASME B89.7.4.1-2005, Measurement Uncertainty And Conformance Testing: Risk Analysis — provides guidance on the risks involved in any product acceptance / rejection decision.
	ASME B89.7.5-2006, Metrological Traceability of Dimensional Measurements to the SI Unit of Length — describes the issues associated with claiming measurement traceability and provides a checklist for asserting metrological traceability of dimensional measurements.