Method VAR assumes that the variance of the residual error is the sum of the statistically independent proportional and additive components this method can be coded in three ways. Different approaches have been proposed, but a comparison between approaches is still lacking.Methods: The theoretical background of the methods is described. When the result of an analysis is used for simulation purposes, it is essential that the simulation tool uses the same method as used during analysis.Ībstract = "Introduction: In pharmacokinetic modelling, a combined proportional and additive residual error model is often preferred over a proportional or additive residual error model. Using method SD, the values of the parameters describing residual error are lower than for method VAR, but the values of the structural parameters and their inter-individual variability are hardly affected by the choice of the method.Ĭonclusion: Both methods are valid approaches in combined proportional and additive residual error modelling, and selection may be based on OFV. Results: The different coding of methods VAR yield identical results. Using datasets from literature and simulations based on these datasets, the methods are compared using NONMEM. Method SD assumes that the standard deviation of the residual error is the sum of the proportional and additive components. Methods: The theoretical background of the methods is described. Different approaches have been proposed, but a comparison between approaches is still lacking.
Introduction: In pharmacokinetic modelling, a combined proportional and additive residual error model is often preferred over a proportional or additive residual error model.