The New Measurement Concept Explained by Using an Introductory Example

Abstract

A new measurement concept has been published in the name of seven global scientific and technical organizations. The concept is based exclusively on observable quantities and solely aims at the comparability of results between laboratories. The main tasks of the analyst to obtain results that are comparable with those of other laboratories are to properly validate the analytical procedure and establish adequate calibration or control for each value and each condition defined in the procedure; if necessary, to correct for recognized significant systematic effects; and to evaluate the combined standard uncertainty and report the result as an interval (value and uncertainty). The concept has been adopted by all leading national metrology institutes around the world, for example, by the National Institute for Standards and Technology of the United States. In this article, an example for the implementation of measurement uncertainty in lectures on analytical chemistry is presented. Furthermore, the measurement concept published in the Guide to the Expression of Uncertainty in Measurement (GUM) is compared with the current state-of-practice.

“The Price is Right” for Your Classroom

“…We contend, however, that students are capable of understanding the proper use and function of volumetric glassware and that this understanding may enable them to both perform better in lab and also appreciate the nature of quantitative measurements. Indeed, we hold that such an understanding is an important prerequisite before moving on to more sophisticated understandings of measurement uncertainty (7).…”