Limits...
A Careful Consideration of the Calibration Concept

View Article: PubMed Central - PubMed

ABSTRACT

This paper presents a detailed discussion of the technical aspects of the calibration process with emphasis on the definition of the measurand, the conditions under which the calibration results are valid, and the subsequent use of the calibration results in measurement uncertainty statements. The concepts of measurement uncertainty, error, systematic error, and reproducibility are also addressed as they pertain to the calibration process.

No MeSH data available.


A schematic diagram depicting the distribution of potential errors; it is assumed that the repeated measurements occurred over a sufficiently long time to include all reproducibility effects. (a) Repeated measurements with excellent reproducibility, a large estimated systematic error, and a significant uncertainty associated with the realization of the measurand as represented by the large “uncertainty bars”; (b) repeated measurements with no estimated systematic error, small uncertainty associated with the realization of the measurand, and poor reproducibility as represented by the large spread in the data points; (c) the typical case combining estimated systematic error, uncertainty associated with realizing the measurand, and poor reproducibility.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4862813&req=5

f4-j62phi: A schematic diagram depicting the distribution of potential errors; it is assumed that the repeated measurements occurred over a sufficiently long time to include all reproducibility effects. (a) Repeated measurements with excellent reproducibility, a large estimated systematic error, and a significant uncertainty associated with the realization of the measurand as represented by the large “uncertainty bars”; (b) repeated measurements with no estimated systematic error, small uncertainty associated with the realization of the measurand, and poor reproducibility as represented by the large spread in the data points; (c) the typical case combining estimated systematic error, uncertainty associated with realizing the measurand, and poor reproducibility.

Mentions: Systematic Error is the (mathematical) expectation value of the error. It can be estimated as the mean error in the reported value of a measuring instrument or of an artifact. Similar to the case of error, the systematic error is never exactly known because we never know the “true value” and we cannot perform an infinite number of measurements of a standard to produce the expectation value. The estimated systematic error may be determined from the mean of a series of repeated measurements or as a calculated value corresponding to a known systematic effect. Figure 4(a) illustrates a series of measurements that have good reproducibility but contain a large estimated systematic error in addition to a significant uncertainty associated with the realization of the measurand. As previously described, realization of the measurand includes the uncertainty associated with the reference standard under the conditions employed during the calibration.


A Careful Consideration of the Calibration Concept
A schematic diagram depicting the distribution of potential errors; it is assumed that the repeated measurements occurred over a sufficiently long time to include all reproducibility effects. (a) Repeated measurements with excellent reproducibility, a large estimated systematic error, and a significant uncertainty associated with the realization of the measurand as represented by the large “uncertainty bars”; (b) repeated measurements with no estimated systematic error, small uncertainty associated with the realization of the measurand, and poor reproducibility as represented by the large spread in the data points; (c) the typical case combining estimated systematic error, uncertainty associated with realizing the measurand, and poor reproducibility.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862813&req=5

f4-j62phi: A schematic diagram depicting the distribution of potential errors; it is assumed that the repeated measurements occurred over a sufficiently long time to include all reproducibility effects. (a) Repeated measurements with excellent reproducibility, a large estimated systematic error, and a significant uncertainty associated with the realization of the measurand as represented by the large “uncertainty bars”; (b) repeated measurements with no estimated systematic error, small uncertainty associated with the realization of the measurand, and poor reproducibility as represented by the large spread in the data points; (c) the typical case combining estimated systematic error, uncertainty associated with realizing the measurand, and poor reproducibility.
Mentions: Systematic Error is the (mathematical) expectation value of the error. It can be estimated as the mean error in the reported value of a measuring instrument or of an artifact. Similar to the case of error, the systematic error is never exactly known because we never know the “true value” and we cannot perform an infinite number of measurements of a standard to produce the expectation value. The estimated systematic error may be determined from the mean of a series of repeated measurements or as a calculated value corresponding to a known systematic effect. Figure 4(a) illustrates a series of measurements that have good reproducibility but contain a large estimated systematic error in addition to a significant uncertainty associated with the realization of the measurand. As previously described, realization of the measurand includes the uncertainty associated with the reference standard under the conditions employed during the calibration.

View Article: PubMed Central - PubMed

ABSTRACT

This paper presents a detailed discussion of the technical aspects of the calibration process with emphasis on the definition of the measurand, the conditions under which the calibration results are valid, and the subsequent use of the calibration results in measurement uncertainty statements. The concepts of measurement uncertainty, error, systematic error, and reproducibility are also addressed as they pertain to the calibration process.

No MeSH data available.