Closeness of agreement between indications obtained using calibrators in the first step of a calibration and indications predicted by the calibration function for the calibrators’ reference quantity values.
Notes: - The concept applies to calibration functions of any mathematical form. The term "linearity" is historical and refers to a time when calibration graphs were constructed on paper and were invariably considered to be linear.
- Linearity of calibration may be expressed by measures of agreement (for example, correlation coefficient) or deviation (for example, standard error of regression), obtained by regression of calibration data or assessed from a residual plot.
- Linearity of calibration is assessed during procedure validation.
- Calibration linearity should not be confused with linearity of a measuring system.
Source:
PAC, 2021, 93, 997. 'Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)' on page 1008 (https://doi.org/10.1515/pac-2019-0819)