RE: [NMusers] Interindividual variability in residual variance

Dear Mahesh,

 

In order for the IIV in RV to be implemented, it is necessary that you use
the INTERACTION option in $EST, even if you use the additive error.

 

Best regards,

Mats

 


Mats Karlsson, PhD
Professor of Pharmacometrics
Div. of Pharmacokinetics and Drug Therapy
Dept. of Pharmaceutical Biosciences
Faculty of Pharmacy
Uppsala University
Box 591
SE-751 24 Uppsala
Sweden
phone +46 18 471 4105
fax +46 18 471 4003
mats.karlsson_at_farmbio.uu.se

  _____


From: owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com] On
Behalf Of Samtani, Mahesh [PRDUS]
Sent: Wednesday, July 11, 2007 14:27
To: nmusers_at_globomaxnm.com
Subject: [NMusers] Interindividual variability in residual variance

 

Dear NMusers,

I have run in to an old problem that Vladimir once described here on the
users net. I am trying to implement inter-individual variability in residual
variance and the corresponding OMEGA is not being iterated. Usually, in Dr.
Karlsson's work this error structure is implemented on a proportional or
proportional+additive EPS model. I am wondering if my problem is because I
am trying to implement ETA on EPS using the transform both sides approach as
follows?

 

$ERROR

CALLFL=0

IPRED = -5

IF (F.GT.0) IPRED = LOG(F)

IRES=DV-IPRED

W=1

IWRES=IRES/W

Y = IPRED + EXP(ETA(.))*EPS(1)

 

Kindly advice...MNS

 

--------Cut here

From: "Piotrovskij, Vladimir [PRDBE]" - VPIOTROV_at_PRDBE.jnj.com

Subject: [NMusers] Implementation of interindividual variability in residual
variance

Date: 2/17/2004 9:37 AM

 

Dear NONMEM users,

 

I am trying to implement an interidividual variability in

the residual variance using an additional random effect:

 

$ERR

 Y = F + EXP(ETA(.))*EPS(1)

 

It turned out the corresponding OMEGA was not iterated, and the final
estimate

did not differ from the initial value. Below is an example control stream

and the output illustrating the problem (Note, the actual model I work with
is more complicated).

 

Thanks in advance.

 

Best regards,

Vladimir

--------Cut here

 



Received on Wed Jul 11 2007 - 16:17:40 EDT