NONMEM Users Network Archive

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RE: Steady state model

From: Matt Hutmacher <matt.hutmacher>
Date: Thu, 6 Aug 2009 12:17:37 -0400

Dear Mark,

 

Vonesh and Chinchilli discuss an R^2 adapted for generalized nonlinear
mixed-effects models. The derivation they describe needs a reference =
model
in order to compute the relative amount of explained variation and they
discuss the undervalue or R^2 computed for the population – see

Vonesh, E.F., Chinchilli, V.M. (1997). Linear and Nonlinear Models for =
the
Analysis of Repeated Measurements. New York, NY: Marcel Dekker. p. =
420-423

In general, however I agree with Matt’s response below, and would look =
into
the following manuscripts for demonstrating the adequacy of your model:

 
<http://www.ncbi.nlm.nih.gov/pubmed/16906454?ordinalpos=4&itool=Entre=
zSystem
2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVD=
ocS
um> Metrics for external model evaluation with an application to the
population pharmacokinetics of gliclazide.

Brendel K, Comets E, Laffont C, Laveille C, Mentré F.

Pharm Res. 2006 Sep;23(9):2036-49. Epub 2006 Aug 12.

 
<http://www.ncbi.nlm.nih.gov/pubmed/16284919?ordinalpos=69&itool=Entr=
ezSyste
m2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RV=
Doc
Sum> Prediction discrepancies for the evaluation of nonlinear =
mixed-effects
models.

Mentré F, Escolano S.

J Pharmacokinet Pharmacodyn. 2006 Jun;33(3):345-67. Epub 2005 Nov 13.

 

Hope this helps.


Kind regards,
Matt

 

From: owner-nmusers
On
Behalf Of Fidler,Matt,FORT WORTH,R&D
Sent: Thursday, August 06, 2009 11:36 AM
To: Mark Sale - Next Level Solutions
Cc: nmusers
Subject: RE: [NMusers] Steady state model

 

Can't you just explain that r2 is not a good measurement for goodness of =
fit
for these types of models?

 

Matt.

 

  _____

From: owner-nmusers
On
Behalf Of Mark Sale - Next Level Solutions
Sent: Thursday, August 06, 2009 9:39 AM
Cc: nmusers
Subject: RE: [NMusers] Steady state model





Does anyone have any reference for "typical" R^2 for pk/pd =
relationships. I
have an analysis with an R^2 of 0.13 (highly significant), and the =
sponsor
is unimpressed - thinking that an R^2 should be > 0.9 - apparently like =
it
was in physics class.


Mark Sale MD
Next Level Solutions, LLC
www.NextLevelSolns.com
919-846-9185
  

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Thank you.



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Received on Thu Aug 06 2009 - 12:17:37 EDT

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