Table 1. A Summary of the Figures of Merit Used for Method Characterization^a.

characteristic	description	FoM	interpretation
accuracy	closeness of agreement between measurement results and the accepted reference values		total prediction error
trueness	difference between the expected measurement results and the accepted reference values		average of the residuals; systematic component of the total error (i.e., constant offset)
precision	closeness of agreement between independent measurement results obtained with the same method in different measurement facilities with different operators using different equipment		width of residuals distribution; random component of the total error

^ax̂_i and x_i are the predicted and assigned reference values, respectively, for the test sample i, and N is the number of samples in the TEST set. Accuracy = reproducibility + trueness (RMSEP² ≅ SEP² + BIAS²), as from ISO 5725 (ref (39)).