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From: Paul Matthew Westwood <pwestwood02>
Date: Tue, 22 Jul 2008 10:09:44 +0100

Hello all,

I wonder if someone can give me some tips on PPC.
I am working on a midazolam dataset with a pediatric population, and have d=
ecided to use PPC as a model validation technique. The dataset I am modelli=
ng has up to 43 patients, at different ages, different weights, different t=
imes of dosing and sampling, and different doses. I simulated 100 datasets =
using NONMEM VI, fixing all parameters to the final estimates from the mode=
l. The simulated datasets produced had a large proportion of negative conce=
ntrations, and also a few impossibly large concentration values. Also the m=
edian, 5th and 95th percentiles were not very promising, and the resulting =
graphs not very clean.
Firstly, can I use PPC with any degree of confidence with a dataset such as=
 this, and if so, do I omit the negative concentration values from the anal=

Thanks in advance for any help given.

Paul Westwood,
PhD Student,

Received on Tue Jul 22 2008 - 05:09:44 EDT

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