The concept of measurement uncertainty is continuing to create confusion in the dimensional metrology community. As a supplier of measuring instruments and tools, Mitutoyo America receives many questions from customers about measurement uncertainty. I hope the answers to the questions below, along with the included example, will help reduce some confusion. -JGS What is measurement uncertainty? Measurement uncertainty is the estimation of potential errors in a measurement process. When determining uncertainty, you must consider all factors that impact the variation in your measurement results. Error in the measuring instrument, tool, or gage is just one source of uncertainty. Another contributor is the environment, particularly temperature for dimensional measurements. Other common factors to consider are calibration limits, operators, repeatability, and the geometry and condition of the measured workpiece. How is uncertainty expressed? Say you use an external micrometer to measure...