RE: More Levels of Random Effects
Bill,
Is it really an eta you want, or is this rather solved by different error
models for the different machines?
If still want etas, one way would be to model in the same way as IOV. In the
case of intermachine-variability you would have to assume the variability
between all machines are the same...
Or would you rather assume interindividual variability is different with
different machine, and you then would want one eta for TH(X) for every
machine...? It depends on what you mean by different slope every day,
regarding on what your experiments like, but calibration differences should
perhaps be taken care of by looking into your error model, eta on epsilon
for starters...
Without knowing your structure of data, a short example of IOV-like
variability would be:
MA1=0
MA2=0
IF(MACH=1)MA1=1
IF(MACH=2)MA2=1
;Intermachine variability:
ETAM = MA1*ETA(Y)+MA2*ETA(Z)
PAR= TH(X) *EXP(ETA(X)+ETAM)
$OMEGA
value1
$OMEGA BLOCK(1) value2
$OMEGA BLOCK(1) same
/Johan
_________________________________________
Johan Wallin, M.Sci./Ph.D.-student
Pharmacometrics Group
Div. of Pharmacokinetics and Drug therapy
Uppsala University
_________________________________________
Quoted reply history
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Denney, William S.
Sent: den 15 oktober 2008 14:39
To: [email protected]
Subject: [NMusers] More Levels of Random Effects
Hello,
I'm trying to build a model where I need to have ETAs generated on
separately for the ID and another variable (MACH). What I have is a PD
experiment that was run on several different machines (MACH). Each
machine appears to have a different slope per day and a different
calibration. I still need to keep some ETAs on the ID column, so I
can't just assign MACH=ID.
I've heard that there are ways to do similar to this, but I have been
unable to find examples of how to set etas to key off of different
columns.
Thanks,
Bill
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