Accuracy & Uncertainty

The other day I found a very interesting article written by Devin Brent Ellis* about a topic I often ponder when customers talk about their goals and intentions.

He said about the relationship of accuracy to uncertainty:


"Life is full of uncertainty. In our daily lives, we recognize that anything we try to achieve or objective we try to meet will have an uncertain outcome and rarely will anything go according to plan. Einstein theorized that there is no uncertainty in nature, maintaining that the uncertainty only exists in our knowledge of it. Many scientists and physicists may disagree with Einstein in this regard, but wherever one might land on the subject, it is well established that the uncertainty of things weighs heavily in our lives.

In measurement, as in life, uncertainty has an important economic consequence for calibration and measurement activities. Measurement Uncertainty (not to be confused with measurement error) is a condition where a lack of information leads to an inadequate or incomplete measured result. Put in everyday terms, no one can state with any certainty that their expensive quartz watch is maintaining UTC time at 100% accuracy, but they can state that it is 99.9998% accurate “plus or minus” 0.1 seconds per day or that a measuring stick may be a meter in length “give or take” a centimeter. Every measurement, no matter how precise, always has a margin of doubt. Therefore, all measurements are subject to uncertainty, and by international consensus, a measurement result is only complete when it is accompanied by a statement of associated uncertainty."

and further

"In quality assurance, we rely heavily on measurement and we must consider that there are numerous contributors to uncertainly in all of our measurement systems. In a typical manufacturing environment, there are thousands of precision measurement devices, hundreds of operators using them, harsh environmental conditions, random processing events, even insufficient training or management contributing uncertainty to the measurement system as a whole. It is for this reason that companies rely on their calibration efforts to help maintain measurement and test equipment (M&TE), if not the entire measurement system. To perform these calibration functions without compromise, it is crucial that quality professionals choose and utilize effective calibration management software not only to track and maintain M&TE, but to effectively and completely estimate the uncertainty contributors in the measurement system. In the end, we all must deal with the uncertainty in our lives, but with so many tools available to us, there is no reason to suffer uncertainty in our work. After all, the safety and quality of our products depend on it."


Brent, thank you so much. You hit the nail accurate on the head! 

*Devin Brent Ellis is Director of Development and Client Solutions at CyberMetrics Corporation.