Re: Parameterization!!!

From: "Jean-Xavier.Mazoit@kb.u-psud.fr" <jean-xavier.mazoit@kb.u-psud.fr> Subject: Re: Parameterization!!! Date: Thu, 10 May 2001 17:33:28 +0200 My English is not good enough to let me adequately respond to Nick. Indeed, I use compartmental models and parameterization with CL and V. However, I do not think that kinetic analysis is only for fun. It is primarily to make dosing better for the patients. In their examples, both Nick and Stephen use a one-compartment model, which is easily made linear by a logarithmic transformation. With a two-compartment model, things are not so simple and, as Stephen pointed, the Fisher matrix becomes very difficult to analyse in case of reparameterization with the first order approximation made by NONMEM (I imagine that it is the same with second order methods). It was in that sense that I addressed the problem of bootstrapping errors (non-parametric bootstrap as opposed to bootstrapping original data). Then, I prefer to have a more moderate opinion on modelling. I am never confident on models, and I often check the reliability of my models by comparing their results with those of simple non-compartmental analysis. Thank to both for this exciting discussion Jean Xavier Mazoit MD, PhD Laboratoire d'Anesthésie Université Paris-Sud Faculté de Médecine du Kremlin-Bicêtre F-94276 Bicêtre France Tel. (33) (0)1 49 59 67 35-37 (33) (0)1 45 21 34 41 (Hopital) Fax (33) (0)1 45 21 28 75 e-mail Jean-Xavier.Mazoit@kb.u-psud.fr