Division C.3.1 Definitions

Repeatability the value below which the absolute difference between single test results obtained under repeatability conditions (i.e., same sample, same operator, same apparatus, same laboratory, and short interval of time) may be expected to lie within a specific probability (typically 95 %) and hence r = 2,8 × s_r.

Standard deviation calculated from results generated under repeatability conditions.

Relative standard deviation calculated from results generated under repeatability conditions$\left[\left(s_r∕\bar{x}\right)\times 100\right]$.

Reproducibility the value below which the absolute difference between single test results obtained under reproducibility conditions (i.e., on identical material obtained by operators in different laboratories, using the standardised test method), may be expected to lie within a certain probability (typically 95 %); R = 2,8 × s_R.

Standard deviation, calculated from results under reproducibility conditions.

Relative standard deviation calculated from results generated under reproducibility conditions$\left[\left(s_R∕\bar{x}\right)\times 100\right]$.

Limit of detection, smallest measured content, from which it is possible to deduce the presence of the analyte with reasonable statistical certainty. The limit of detection is numerically equal to three times the standard deviation of the mean of blank determinations (n> 20).

Limit of quantification, lowest content of the analyte which can be measured with reasonable statistical certainty. If both accuracy and precision are constant over a concentration range around the limit of detection, then the limit of quantification is numerically equal to six or ten times the standard deviation of the mean of blank determinations (n> 20).

Combined standard measurement uncertainty obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model^f1.

The expanded measurement uncertainty, using a coverage factor of 2 which gives a level of confidence of approximately 95 % (U = 2u).

Maximum standard measurement uncertainty.