[Products] What is uncertainty in measurement, and how is it determined?
Uncertainty in measurement is defined in The Guide to the Expression of Uncertainty in Measurement (the GUM) published by the International Organization for Standardization (ISO) as "the parameter associated with the result of a measurement or analysis that characterizes the dispersion of the values that could reasonably be attributed to the measurand." You may regard an uncertainty in measurement as a quantitative method for expressing measurement reliability, which characterizes the range of the expressed values within which the true value of a measurand lies. In 1993, for defining and expressing the quality of measurement results with a unified parameter, the ISO published the GUM in association with international organizations such as the BIMP, IES, IFCC, IUPAC, IUPAP, and OLML. According to the GUM, uncertainty is calculated using four steps: 1) setting a relational model for the parameters; 2) calculating the input estimates and standard uncertainty of each input estimate; 3) determining the combined standard uncertainty; and 4) determining the expanded uncertainty.