How to Calculate Combined Uncertainty with Different Units of Measure

Calculating Combined Uncertainty

Most metrologists know how to calculate combined uncertainty, but few know how to do it using sensitivity coefficients. Most likely, it is a section of the Guide to the Expression of Uncertainty in Measurement (GUM) that you have skipped over again and again. Well, in this 14 page guide, am going to teach you how to calculate combined uncertainty using 3 different methods…

• Sensitivity Coefficients
• Fractional Uncertainty
• Mathematical Simulation

Sensitivity Coefficients

Wish you could use sensitivity coefficients to calculate uncertainty, but don’t know how? Well, in this guide, I will teach you everything that you need to know about using sensitivity coefficients to calculate measurement uncertainty. Plus, I have included some great examples for using sensitivity coefficients in common measurement situations.

Fractional Uncertainty

Ever heard of fractional uncertainty? Probably not, unless you are a physicist. I found this method in some old textbooks on uncertainty analysis; and, it works really well! Better yet, it is quicker and easier to use than sensitivity coefficients. Makes you wonder what other methods are missing from the GUM.

Mathematical Simulation

Do not confuse this with Monte Carlo simulation. That is an entirely different method. Mathematical simulation is the method simulating measurement results based on realistic and anticipated changes to a variable. It is my favorite method, and much faster than calculating sensitivity coefficients. Using mathematical simulation will get you the same results without all of the work, which will make you more productive!