Measurement Uncertainty

Measurement Uncertainty – this refers to the approximate amount that the test or certified value may differ from the true value. This is calculated by combining the level of potential error from each step of the manufacturing and testing process, as every step brings with it its own small opportunity for error. This is expressed as a plus/minus range in which the true value falls.

• Tolerance vs uncertainty
• Tolerance is the range between maximum and minimum allowed values for measurement – this is relative to what is actually possible, as human touch processes are never 100% accurate. Tolerance is how much uncertainty or discrepancy is allowed for test results.
• Certified uncertainty is the range within the tolerance limits in which we believe the true value lies. The certified uncertainty includes allowances from all errors that could happen during the manufacture, testing, packaging, transportation, and storage of a CRM product.
• Example – our 17034 scope of accreditation provides concentration ranges within which we can work to create our products. The scope also dictates Relative uncertainty, which is different from our certified uncertainty. Relative uncertainty here describes the ratio of absolute (certified) uncertainty to the measured value that is allowable under the scope.