FITTING DRUG CONCENTRATION DATA ACCORDING TO ITS CREDIBILITY: DETERMINING THE ASSAY ERROR PATTERN

Many methods have been used to fit a pharmacokinetic model to the serum level data. Unity weighting, weighting by the reciprocal of the measured concentration (or of its squared value), the use of a constant coefficient of variation, and others have been employed. Use of various weighting schemes has often been regarded as an art, in order to get the smallest sum of squares of the residuals, the "best" fit.