Comparison of alternative measurement methods Original Research Article

A procedure to compare the performance (precision and bias) of an alternative measurement method and a reference method has been extensively described. It is based on ISO 5725-6 which has been adapted to the intralaboratory situation. This means that the proposed approach does not evaluate the reproducibility, but considers the (operator+instrument+time)-different intermediate precision and/or the time-different intermediate precision. A 4-factor nested design is used for the study. The calculation of different variance estimates from the experimental data is carried out by ANOVA. The Satterthwaite approximation is included to determine the number of degrees of freedom associated with the compound variances. Taken into account the acceptable bias, the acceptable ratio between the precision parameters of the two methods, the significance level α and the probability β to wrongly accept an alternative method with an unacceptable performance, the formulae to determine the number of measurements required for the comparison are given. For the evaluation of the bias, in addition to the point hypothesis testing, the interval hypothesis testing is also included as an alternative. Two examples are given as an illustration of the proposed approach.