Analytical goals for rectilinear calibration functions.
Analytical goals for rectilinearity based on within-subject biological variation have not yet been advocated. On the other hand, the statistical tests to evaluate rectilinearity may be too restrictive for clinical purposes. If rectilinearity of the least-squares regression is rejected by the statistical test used, we propose to compare the systematic error introduced using such a regression line as the calibration function, with the allowable total error. Since total error ideally should be less than the within-subject biological coefficient of variation (C.V.Bw) the goal for rectilinearity we propose is that the maximum allowable systematic relative error produced by the calibration function (LoRi) when a lack of rectilinearity really occurs is: LoRi < C.V.Bw -1.96 C.V.M, where C.V.M is the between-run metrological coefficient of variation of the measurement procedure, corresponding to the value of concentration under study.
Fuentes-Arderiu
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Servei de Bioquímica Clínca, Hospital Prínceps d'Espanya, L'Hospitalet de Llobregat, Barcelona, Spain.
Alía
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Machuca
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D000465:Algorithms; D002138:Calibration / Q000592:standards*; D002624:Chemistry, Clinical / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D016018:Least-Squares Analysis; D012044:Regression Analysis