Another voice on Measurement Uncertainty

By Sten Westgard, MS

While Dr. Westgard has spoken about the "War of Words" between Uncertainty and Total Error in several essays (here, here and here most recently), we thought readers might want an additional perspective on the issue.

Dietmar Stockl, an expert in statistics and laboratory quality control from across the Atlantic, graces us with an guest essay on the calculation, use, benefits and limitations of measurement uncertainty: Time to Engage in Measurement Uncertainty. Dr. Stockl provides an in-depth look at uncertainty concepts and calculations, as well as a moderate viewpoint on the use of the term. He views both Total Error and Measurement Uncertainty are useful concepts and believes there is room in the world for both of them. It's not necessary for one term to eliminate the other.

Not so coincidentally, a colleague of Dr. Stockl's, Linda Thienpont, has a letter in Clinical Chemistry talking about the attempt to incorporate bias into the calculation of measurement uncertainty. If bias can be thrown into the uncertainty calculations, a case could be made that Total Error is no longer necessary. Dr. Thienpont points out that slipping bias into the uncertainty calculations is not a good idea and can lead to distorted results. She concludes that bias must remain separate from uncertainty calculations, which means another approach like Total Error is required to account for it.

See more at Thienpont LM. Calculation of measurement uncertainty-Why bias should be treated separately. Clin Chem 2008;54:1587 (subscription required) -----