Re: NONMEM code for Mixture Model
Hi Nidal,
Thank you for your help. I searched the NONMEM user guides and finally found an
example of mixture model. It is on part VIII, page 456. I have tried the codes
and it works for my model. It improved the fitting but I noticed some of IWRES
increased dramatically. I am trying to figure out why.
Thanks again,
Best regards,
Huali
Quoted reply history
----- Original Message -----
From: [email protected]
To: Huali Wu
Cc: [email protected]
Sent: Thursday, March 12, 2009 3:44 PM
Subject: Re: [NMusers] NONMEM code for Mixture Model
Hi Huali,
You could use $MIX. Please see the NM help files for $MIX. You have to
specify the number of populations (in your case 2) so
$MIX
NSPOP=2
P(1)=THETA(4)
P(2)=1.-THETA(4)
Then use
EST= MIXEST
Hopefully this helps.
Best,
Nidal
Nidal AL-Huniti, PhD
Associate Director, Modeling and Simulations
ICON Development Solutions SM
On 3/12/09, Huali Wu <[email protected]> wrote:
Dear NMusers:
I am working on dataset with high variability on clearance and patients in
different disease states seems have different distribution of clearance. So I
want to try the mixture model but I don't know how to do the coding. I listed
the code of my base model as below:
$PROB 1hr IV INFUSION SINGLE DOSE WITHOUT COVARIATES
$DATA data01.CSV IGNORE=C
$INPUT ID TIME DV AMT RATE MDV
$SUBROUTINES ADVAN9 TRANS1 TOL=5
$MODEL NPAR=3, NCOMP=1, COMP=(CENTRAL,DEFOBS)
$PK
V1 = THETA(1)*EXP(ETA(1))
VM = THETA(2)*EXP(ETA(2))
KM = THETA(3)
S1 = V1
$ERROR
Y=F+F*EPS(1)+EPS(2)
IPRED=F
IRES=DV-IPRED
IF(AMT.NE.0)W=1
IF(AMT.EQ.0)W=F
IWRES=IRES/W
$DES
C1 = A(1)/V1
DADT(1) = - C1*VM/(KM+C1)
$THETA (0, 4.47) (0, 155) (0, 1380)
$OMEGA BLOCK (2)
0.5
0.3 0.9
$SIGMA (0.01) (0.1)
$EST POSTHOC METHOD=1 MAXEVAL=9990 PRINT=5
$COV
$TABLE ID TIME DV AMT RATE V1 VM KM IWRES IPRED NOPRINT FILE=TAB4
ONEHEADER
$SCAT (RES WRES) VS TIME BY ID
Any suggestion will be highly appreciated!
Best regards,
Huali