Re: [NMusers] Two dependent variables

Hi,

The 'FLAG' method is a trick that only works with 2 DVs. It is also a bit inefficient because it requires that both the PK and PD prediction are calculated but only one is used.

A more general method uses IF THEN blocks e.g. if you have a data item DVID with the value 1 with a conc observation and the value 2 with an effect observation of one type and value of 3 with an effect observation of a different type:

CONC=F
IF (DVID.EQ.1) THEN
   Y=CONC + ERR(1)
ENDIF
IF (DVID.EQ.2) THEN
   Y=EMAX2*CONC/(EC502+CONC) + ERR(2)
ENDIF
IF (DVID.EQ.3) THEN
   Y=EMAX3*CONC/(EC503+CONC) + ERR(2)
ENDIF

Nick

>
> Yes, you could do a simultaneous fitting with the same control stream in NM. For example you could
> have a dummy variable (Flag) that tells NM which likelihood function goes with which data. See below
>
>
>
> Flag 0 = PK, Flag 1=PD
>
>
>
> $ERROR
>
> Y=CONC*(1-Flag) + EFF* Flag
>
>
>
> Hopefully this would help.
>
>
>
> Best,
>
> Nidal AL-Huniti, PhD
>
>
> On 1/30/07, navin goyal <navin1180_at_gmail.com > wrote:
>
> Hello,
> I was wondering if I could model two DVs simultaneously with the same control stream.
> Like have to equations A=(equation)
> B= (equation)
>
> I have data for two different drugs from same patients
> Could I do it nomem ? and if yes how do I do it?
>
> Any help is appreciated,
> Thanks
>
>
>
>
>



--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand
email:n.holford_at_auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556
http://www.health.auckland.ac.nz/pharmacology/staff/nholford/
Received on Tue Jan 30 2007 - 15:26:27 EST