Dear Group,
I want to implement M3 method with log transformed data. I want to use the
additive error model in log domain and wrote the following code and the runs
are fine. I want to make sure that I am doing this right.
$ERROR
CALLFL=0
IPRED=-3
IPRED=LOG(F)
W=THETA(4) ;LOG ADDITIVE ERROR
LOQ=LOG(0.03);loq is 0.3
DUM=(LOQ-IPRED)/W
CUMD=PHI(DUM)
IF (BQL.EQ.0) THEN
IWRES = (DV-IPRED)/W
F_FLAG=0
SIMDV = LOG(F)+W*ERR(1)
Y=F+W*ERR(1)
ENDIF
IF (BQL.EQ.1) THEN
IWRES = 0
F_FLAG=1
Y=CUMD
ENDIF
$EST METHOD=COND INTER LAPLACIAN
$SIGMA 1 FIX
Thank you for your help.
Regards,
Ayyappa
M3 method with log transformed data
Dear Ayappa,
This looks fine. However, with NONMEM 7.2 you can also write it as below.
Estimating SIGMA rather than fixing it and estimate a multiplicative THETA
may have speed advantages (and simpler coding for the new methods).
$ERROR
CALLFL=0
IPRED=-3
IPRED=LOG(F)
W=SIGMA(1,1) ;LOG ADDITIVE ERROR
LOQ=LOG(0.03);loq is 0.3
DUM=(LOQ-IPRED)/W
CUMD=PHI(DUM)
IF (BQL.EQ.0) THEN
IWRES = (DV-IPRED)/W
F_FLAG=0
SIMDV = LOG(F)+ERR(1)
Y=F+W*ERR(1)
ENDIF
IF (BQL.EQ.1) THEN
IWRES = 0
F_FLAG=1
Y=CUMD
ENDIF
$EST METHOD=COND INTER LAPLACIAN
$SIGMA 1
Best regards,
Mats
Mats Karlsson, PhD
Professor of Pharmacometrics
Dept of Pharmaceutical Biosciences
Faculty of Pharmacy
Uppsala University
Box 591
75124 Uppsala
Phone: +46 18 4714105
Fax + 46 18 4714003
Quoted reply history
From: [email protected] [mailto:[email protected]] On
Behalf Of Ayyappa Chaturvedula
Sent: 22 November 2012 00:07
To: [email protected]
Subject: [NMusers] M3 method with log transformed data
Dear Group,
I want to implement M3 method with log transformed data. I want to use the
additive error model in log domain and wrote the following code and the runs
are fine. I want to make sure that I am doing this right.
$ERROR
CALLFL=0
IPRED=-3
IPRED=LOG(F)
W=THETA(4) ;LOG ADDITIVE ERROR
LOQ=LOG(0.03);loq is 0.3
DUM=(LOQ-IPRED)/W
CUMD=PHI(DUM)
IF (BQL.EQ.0) THEN
IWRES = (DV-IPRED)/W
F_FLAG=0
SIMDV = LOG(F)+W*ERR(1)
Y=F+W*ERR(1)
ENDIF
IF (BQL.EQ.1) THEN
IWRES = 0
F_FLAG=1
Y=CUMD
ENDIF
$EST METHOD=COND INTER LAPLACIAN
$SIGMA 1 FIX
Thank you for your help.
Regards,
Ayyappa