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Uncertainty of Error: The Error Dilemma



Charles D. Ehrlich


Measurement error has historically been defined in the metrology community as a difference of 'values,' usually as a difference between a 'measured value' and a 'reference value.' The reference value is sometimes considered to be a 'true value,' which is unknowable, and so the 'measurement error' is then unknowable. However, in some cases the reference value is considered to be a value assigned to a measurement standard (e.g., a 'conventional value'), which can be known. In this case, 'measurement error' is regarded as being knowable and measurable (for example, the 'error of indication of a measuring system'). The characteristic of being "measurable" requires that there be a corresponding 'quantity' that can be measured. When measurement error is considered to be measurable, it must then be regarded as a 'quantity' (and not as a 'quantity value'). Although the concepts of 'quantity' and 'quantity value' are related, they are distinct concepts, and from a terminological perspective the same term ("error") cannot be used for both concepts. This paper addresses the dilemma of how best to regard 'measurement error' and associated concepts: as quantity values or as quantities. This distinction has important implications when considering the concept of 'uncertainty of error,' which arises when error is considered to be measurable.
NCSL International Measure


measurement error, measurement uncertainty, true value


Ehrlich, C. (2016), Uncertainty of Error: The Error Dilemma, NCSL International Measure, [online], (Accessed July 20, 2024)


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Created May 11, 2016, Updated April 12, 2022