MEASUREMENT UNCERTAINTY Continued...
 |
MEASUREMENT UNCERTAINTY |
Definition:
Combined standard uncertainty standard uncertainty of the result of a measurement when that resultis obtained from the values of a number of other quantities, equal to the positive square root of a sum of terms, theterms being the variances or covariances of these other quantities weighed according to how the measurement resultvaries with changes in these quantities
Definition:
Expanded uncertainty: quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction of the distribution of values that could reasonably be attributed to themeasurand.
The fraction may be viewed as the coverage probability or level of confidence of the interval.
To associate a specific level of confidence with the interval defined by the expanded uncertainty requires explicit or implicit assumptions regarding the probability distribution characterized by the measurement result and its combined standard uncertainty. The level of confidence that may be attributed to this interval can be known only to the extent to which such assumptions may be justified.
Definition:
Coverage factor: numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an expanded uncertainty
Definition:
Measurement uncertainty is a parameter used in data processing for the description of both the dispersion of the result and its estimated difference from the accurate value.
Definition:
Measurement uncertainty is defined as: “a parameter, associated with the result of a measurement, that characterises the dispersion of the values that could be reasonably attributed to the measurand” (JCGM, 2008; ISO, 2009).
Definition:
Q. What is uncertainty?
A. In ordinary use, the word 'uncertainty' does not inspire confidence. However, when used in a technical sense it carries a specific meaning. It is a parameter, associated with the result of a measurement (e.g. a calibration or test) that defines the range of the values that could reasonably be attributed to the measured quantity. When uncertainty is evaluated and reported in a specified way, it indicates the level of confidence that the value lies within the range defined by the uncertainty interval.
