RE: Steady state model
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 Matts 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=EntrezSystem
2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocS
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=EntrezSyste
m2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDoc
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
Quoted reply history
From: [email protected] [mailto:[email protected]] 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: [email protected] [mailto:[email protected]] 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
This e-mail (including any attachments) is confidential and may be legally
privileged. If you are not an intended recipient or an authorized
representative of an intended recipient, you are prohibited from using,
copying or distributing the information in this e-mail or its attachments.
If you have received this e-mail in error, please notify the sender
immediately by return e-mail and delete all copies of this message and any
attachments.
Thank you.
<<image001.png>>