NONMEM Users Network Archive

Hosted by Cognigen

RE: covariance step

From: Bhattaram, Atul <Atul.Bhattaram>
Date: Thu, 16 Jul 2009 15:19:36 -0400

Hello

You should increase the upper boundaries. Also you might try using
allometric models while fixing some of the parameters, if data is
limited.

Atul


Venkatesh Atul Bhattaram
Pharmacometrics
Office of Clinical Pharmacology
US Food and Drug Administration


"The contents of this message are mine personally and do not necessarily
reflect any position of the Government or the Food and Drug
Administration."


-----Original Message-----
From: owner-nmusers
On Behalf Of Varsha Mehta
Sent: Thursday, July 16, 2009 1:21 PM
To: nmusers
Subject: [NMusers] covariance step


Dear NONMEM users:

I have a data set for 30 infants where I am running a 2 COMPT PK model.
I got the following error message for the covariance step. I need some
help with trying to fix this error. Any suggestions? should I increase
the upper boundries of initial estimates?



MINIMIZATION SUCCESSFUL
 NO. OF FUNCTION EVALUATIONS USED: 289
 NO. OF SIG. DIGITS IN FINAL EST.: 3.0
0PARAMETER ESTIMATE IS NEAR ITS BOUNDARY
 THIS MUST BE ADDRESSED BEFORE THE COVARIANCE STEP CAN BE IMPLEMENTED

any help is appreciated.
Thanks


Varsha Mehta, MS(CRDSA), Pharm.D., FCCP
Clinical Associate Professor
Pharmacy, Pediatrics and Communicable Diseases
Clinical Pharmacist Neonatal Critical Care
University of Michigan
(O) 734-936-8985
(F) 734-936-6946
varsham

**********************************************************
Electronic Mail is not secure, may not be read every day, and should not
be used for urgent or sensitive issues
Received on Thu Jul 16 2009 - 15:19:36 EDT

The NONMEM Users Network is maintained by ICON plc. Requests to subscribe to the network should be sent to: nmusers-request@iconplc.com.

Once subscribed, you may contribute to the discussion by emailing: nmusers@globomaxnm.com.