8.1 Measurement and Its Uncertainty
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character. Only after the parameter is determined can we show the measurement
result in the form X p = X ± U. Results given is such a form should also be completed
with the probability assigned to that range, which determines that the true value of
the measured quantity lies in the determined range.
In this context, two questions arise:
– How can the measurement uncertainty be determined?
– What uncertainty can be accepted, so that the measurement result can be useful?
8.2 The Reliability and Usefulness of the Measurement
Results
It is clear that every measurement result should include an assigned uncertainty of
measurement. A question arises, if a result includes an uncertainty, can it always be
considered as reliable and useful?
A reliable result is one in the [x − U; x + U] range in which the true value
of the measured quantity is located. A result determined in such a way is a result
that can be trusted. Measurements conducted in some laboratories can have a smaller
uncertainty than those conducted in other laboratories. If, however, in two laboratories
the uncertainties are determined according to the metrological principles, then both
results will be reliable.
The reliable results require a detailed evaluation of all possible sources of the
measurement uncertainty.
Useful results: is a reliable result always useful? In order to address this question,
it is necessary to consider the goal of the measurement and the intended use of the
results. Thus, the measurement result, with the assigned uncertainty, should be useful
for a chosen purpose. Only reliable and useful results can be used when an important
decision will be derived as to whether a given product was made properly, whether
the production process runs properly, or to verify scientific hypotheses.
Useful measurement results shall therefore be accompanied with the well evaluated uncertainty, considered as the range where the result can still be useful for
performing assessments or making decisions. With overestimated uncertainty, the
risk of incorrect assessment can be high enough that, due to the costs of the wrong
decision, the measurement result could be useless.
Definitional uncertainty: the component of measurement uncertainty resulting from the finite amount of detail in the definition of a measurand.
clause 2.27; ISO/IEC Guide 99
119
character. Only after the parameter is determined can we show the measurement
result in the form X p = X ± U. Results given is such a form should also be completed
with the probability assigned to that range, which determines that the true value of
the measured quantity lies in the determined range.
In this context, two questions arise:
– How can the measurement uncertainty be determined?
– What uncertainty can be accepted, so that the measurement result can be useful?
8.2 The Reliability and Usefulness of the Measurement
Results
It is clear that every measurement result should include an assigned uncertainty of
measurement. A question arises, if a result includes an uncertainty, can it always be
considered as reliable and useful?
A reliable result is one in the [x − U; x + U] range in which the true value
of the measured quantity is located. A result determined in such a way is a result
that can be trusted. Measurements conducted in some laboratories can have a smaller
uncertainty than those conducted in other laboratories. If, however, in two laboratories
the uncertainties are determined according to the metrological principles, then both
results will be reliable.
The reliable results require a detailed evaluation of all possible sources of the
measurement uncertainty.
Useful results: is a reliable result always useful? In order to address this question,
it is necessary to consider the goal of the measurement and the intended use of the
results. Thus, the measurement result, with the assigned uncertainty, should be useful
for a chosen purpose. Only reliable and useful results can be used when an important
decision will be derived as to whether a given product was made properly, whether
the production process runs properly, or to verify scientific hypotheses.
Useful measurement results shall therefore be accompanied with the well evaluated uncertainty, considered as the range where the result can still be useful for
performing assessments or making decisions. With overestimated uncertainty, the
risk of incorrect assessment can be high enough that, due to the costs of the wrong
decision, the measurement result could be useless.
Definitional uncertainty: the component of measurement uncertainty resulting from the finite amount of detail in the definition of a measurand.
clause 2.27; ISO/IEC Guide 99