GUIDELINES FOR EXPRESSING THE UNCERTAINTY OF MEASUREMENT RESULTS CONTAINING UNCORRECTED BIAS

This paper proposes a method to extend the current ISO Guide to the Ex pression of Uncertainty in Measurement to include the case of known, b ut uncorrected, measurement bias. It is strongly recommended that meas urement results be corrected for bias, however in some situations this may not be practical, hence an extension of the Guide is proposed to address this special situation. The method keeps with the spirit of th e Guide in maintaining the link between uncertainty and statistical co nfidence. Similarly, the method maintains the transferability of one u ncertainty statement to be included as a component in another uncertai nty analysis. The procedure involves modifying the calculation of the expanded uncertainty, allowing it to become asymmetric about the measu rement value. The method is compared to other alternative procedures, and an illustration of how it affects tolerance zones is presented.