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RE: OFV higher with FOCEI than FO

From: Hussein, Ziad <Ziad.Hussein>
Date: Wed, 10 Dec 2008 15:07:30 -0000

Hi Ayyappa,
Your understanding is correct that the objective functions from FOCEI
and FO can not be compared.
Dr Ziad Hussein
Senior Director, Pharmacometrics
ICON Development Solutions
United Kingdom


From: owner-nmusers
On Behalf Of ayyappa.5.chaturvedula
Sent: 10 December 2008 14:40
To: owner-nmusers
Subject: [NMusers] OFV higher with FOCEI than FO

Dear All,

I am analyzing a data set pooled from 4 clinical studies with rich
sampling. When I fit a 2 comp oral absorption model with lag time using
FO, I got successful minimization with COV step, but minimization was
not successful when I used FO parameter estimates as initial estimates
for FOCE run. When I used FOCE with INTER minimization was successful
with COV step but the OFV is much higher (~25000 vs 20000) with FOCEI
estimation than FO. The parameter estimates make more sense with FOCEI
than FO. My questions are,

Can we get something like this or I am missing something here?
Can we compare OFV between different estimation methods (my
understanding is no and OFV in case of FO does not make a lot of sense)?

Ayyappa Chaturvedula
1500 Littleton Road,
Parsippany, NJ 07054

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Received on Wed Dec 10 2008 - 10:07:30 EST

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