by Ted Doiron
While check standards will eventually give the most accurate uncertainty for a calibration procedure, the time and expense can be discouraging. Another common method, standard Gage Repeatability and Reproducibility study does not produce anything like the actual uncertainty. It is possible to force variation into the R&R and get a much more useful estimate of uncertainty. This process, which I call the Uncertainty R&R (UR&R), is described along with examples of actual studies made on a typical Universal Length Measuring instrument (ULM). Read Full Article (PDF)
