NONMEM Users Network Archive

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RE: M3 method and multiple LOQ values

From: Mats Karlsson <mats.karlsson>
Date: Thu, 7 Mar 2013 21:15:58 +0100

Dear Rebecca,

 

I think you want to change

DUM=(LOQ-IPRED)

To

DUM=(LOQ-IPRED)/(SIG*IPRED)

 

BTW, with the new NONMEM version, the need to fix SIGMA to 1 is no longer
necessary as you can use SIGMA(1,1) on the right-hand side of expressions in
$ERROR

Your expression would then become

 

$ERROR
IPRED=F
LOQ=LLOQ
DUM=(LOQ-IPRED)/(SQRT(SIGMA(1,1))*IPRED)
CUMD=PHI(DUM)

IF (BQL.EQ.0) THEN
F_FLAG=0
Y=IPRED*(1+ ERR(1))
ENDIF


IF (BQL.EQ.1) THEN
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

 

From: owner-nmusers
Behalf Of Rebecca N. Burns
Sent: 07 March 2013 17:46
To: nmusers
Subject: [NMusers] M3 method and multiple LOQ values

 

All,

 

I am implementing the M3 method using NONMEM7.2. My error structure is
proportional. I have two questions regarding the control stream shown
below.

 

1. Is the control stream correct for a proportional error model?

2. Each DV has its own LOQ so I cannot give one LOQ value. I was
planning to assign a column in my data frame which defines LOQ for each DV.
Is this an appropriate approach?

 

Any input/advice would be much appreciated!

 

Thanks,

 

Rebecca Neal Burns, PharmD, PhD

Post-Doctoral Scholar, Pharmacometrics

Mercer University, Atlanta, GA

  

$ERROR

SIG=THETA(4)
IPRED=F
LOQ=LLOQ
DUM=(LOQ-IPRED)
CUMD=PHI(DUM)

IF (BQL.EQ.0) THEN
F_FLAG=0
Y=IPRED*(1+SIG*ERR(1))
ENDIF


IF (BQL.EQ.1) THEN
F_FLAG=1
Y=CUMD
ENDIF

$EST METHOD=COND INTER LAPLACIAN
$SIGMA 1 FIX

 

 


Received on Thu Mar 07 2013 - 15:15:58 EST

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