ABSTRACT
When reporting the result of a measurement of a physical quantity, it is obligatory that some quantitative indication of the quality of the result be
given so that those who use it can assess its reliability. U.S. Guide to the Expression of Uncertainty in Measurement. ANSI/NCSL
Science
Uncertainty is one part of life that cannot be avoided. Its presence is a constant reminder of our limited knowledge and inability to control each and every factor that influences us. This especially holds true in the physical sciences. Whenever a process is quantified by either modeling or experiments, uncertainty is present. In the beginning of this chapter, the uncertainties present in modeling and experiments are identified. Agreement between modeling and experiment is described in the context of uncertainty. Measurement uncertainties are studied in detail. Conventional methods on how to characterize, quantify, and propagate them are presented. The generic cases of single or multiple measurements of a measurand or of a result are considered. Then, numerical uncertainties associated with measurements are discussed. Finally, uncertainty that results from a lack of knowledge about a variable’s specific value is considered.
