An Intersection: The Contract Review Process, Measurement Decision Risk, and Measurement Uncertainty

At the 2007 NCSLI Workshop and Symposium, Dr. Howard Castrup, in his presentation on ANSI/NCSL Z540.3, remarked to the audience "Don’t just make us report measurement uncertainty and then do nothing with that value." Ten years after that presentation, the calibration industry still struggles to heed Dr. Castrup’s advice. Much confusion remains on why there is more than just reporting an uncertainty value. There are three key areas that will be looked at in this paper: The contract review process, measurement uncertainty, and measurement decision risk. The goal is to inform the reader how these three concepts are related to each, how they affect the overall calibration process, and why this is important. Both the customer and the calibration lab have a responsibility to ensure that the proper measurement decision risk levels are set, communicated, and understood. Once the risk level is established and communicated, the calibration lab will then perform a calibration service that stays within the bounds of that risk level. The goal is to produce a calibration service that is both traceable and meets the customer's measurement decision risk requirement. And lastly, a calibration report must be generated containing the appropriate information.