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According
to:
- “Expression
of the Uncertainty of Measurement in Calibration” (EA-4/02),
- “Guide to
the Expression of Uncertainty in Measurement” (BIPM, IEC, IFCC, ISO, IUPAC,
IUPAP, OIML),
the
statement of the result of a measurement is complete only if it contains both
the value attributed to the measurand and the uncertainty of measurement
associated with that value.
The
uncertainty of measurement is a parameter, associated with the result of a
measurement, that characterises the dispersion of the values that could
reasonably be attributed to the measurand.
The
measurands are the particular quantities subject to measurement, in calibration
or in testing. Each measurand or output quantity Y depends upon a number of
input quantities Xi (i = 1, 2 ,. . ., N) according to the functional relationship:
Y = f(X1,X2, ...,XN)
The model
function “f” is in most cases an analytical expression, but it may also be a
group of such expressions which include corrections that cannot be written down
as one function explicitly.
The
uncertainty of measurement associated with the input estimates is evaluated
according to either:
- Type A
evaluation of standard uncertainty, i. e. the method of evaluating the
uncertainty by the statistical analysis of a series of observations,
- Type B evaluation of standard uncertainty, i. e.
the method of evaluating the uncertainty by means other than the statistical
analysis of a series of observations; in this case the evaluation of the
standard uncertainty is based on some other scientific knowledge.
CEQMAS provides solutions for both Types of evaluation.
The "cequnc" software performs automatically the Type B evaluation of uncertainty of measurement in a variety of applications for Testing and Calibration. Operating in the Excel environment, it approaches the 2nd order evaluation. The case
here reported relates to the Example "1" in Guide to the Expression of Uncertainty in Measurement.
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