Measurement error | Measured quantity value minus a reference quantity value [19]Systematic measurement error: Component of measurement error that in replicate measurements remains constant or varies in a predictable manner [19]Random measurement error: Component of measurement error that in replicate measurements varies in an unpredictable manner [19] | Quantity on the same scale as the measurement scale, relative error, percentwise error, mean square error, root mean square error.Systematic measurement error: BiasRandom measurement error: Standard deviation, variance, coefficient of variation. |
Sensitivity | The sensitivity of a clinical test refers to the ability of the test to correctly identify those patients with the disease. [36]. | Eq. (1)A part of the ROC curve which shows the relation between sensitivity, specificity and the detection threshold. |
Specificity | The specificity of a clinical test refers to the ability of the test to correctly identify those patients without the disease. [36] | Eq. (2)A part of the ROC curve which shows the relation between sensitivity, specificity and the detection threshold. |
Agreement | The degree to which scores or ratings are identical [31] | Continuous: Bland-Altman plotDiscrete: Percentage agreement |
Trueness | Closeness of agreement between the average value obtained from a large series of results of measurement and a true value [37]. | Bias (i.e. the difference between the mean of the measurements and the true value) |
Precision | Closeness of agreement between independent results of measurements obtained under stipulated conditions [37]. | Standard deviation, coefficient of variation |
Repeatability | Precision determined under conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment within short intervals of time [37] | Within-subject standard deviation [38]Repeatability coefficient [38] |
Reproducibility | Precision determined under conditions where test results are obtained with the same method on identical test items in different laboratories with different operators using different equipment [37] | Standard deviation, coefficient of variation |
Accuracy2 | Closeness of agreement between the result of a measurement and a true value (both trueness and precision) [37]Measurement accuracy: Closeness of agreement between a measured quantity and a true quantity value of a measurand [19] | Bias (trueness) and standard deviation/ coefficient of variation (precision)Diagnostic accuracy: Sensitivity and specificitySensitivity and specificity corrected for prevalence as: (sensitivity)(prevalence)+(specificity)(1-prevalence) [39] |
Reliability | Ratio of variability between subjects or objects to the total variability of all measurements in the sample [31] | Intraclass correlation coefficientKappa statistics (categorical data) |