RE: nonmem question regarding condition number
Hi Laureen,
If you want an objective second opinion then make likelihood profiles for both
models.
I expect a very shallow one for at least one maybe two parameters for the
3-compartment model and thus the parameters are not estimated accurately, even
if the objective function goes down.
good luck,
Douglas Eleveld
Quoted reply history
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From: [email protected] [[email protected]] on behalf of
L.A. ten Berg - Lammers [[email protected]]
Sent: Thursday, March 24, 2016 11:10 AM
To: '[email protected]'
Subject: [NMusers] nonmem question regarding condition number
Dear nmusers,
I am currently analyzing PK profiles after a single iv adminstration.
Volunteers were sampled frequently: 12 samples per curve.
For the structural model 2- and a 3-compartment models are compared. The CWRES
vs time plot of the 2-compartment shows the typical wave, indicative for a
3-compartment model. Introduction of a third compartment eliminated the wave,
OFV decreased with 180 points, precision of the estimates did change notably,
but the condition number increased from 998 to 2.0*E16.
Does anyone know how to interpret this large increase in condition number?
Best wishes,
Laureen ten Berg
[Beschrijving: cid:[email protected]]
Laureen ten Berg-Lammers
Hospital Pharmacist
Academisch Medisch Centrum
Universiteit van Amsterdam
Meibergdreef 9 | 1105 AZ Amsterdam | Room: M01-224
Tel: +31(0)20-5662726 | Pager *62726 | [email protected]
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