NONMEM Users Network Archive

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Re: OMEGA selection

From: Ethan Wu <ethan.wu75>
Date: Wed, 15 Apr 2009 10:15:12 -0700 (PDT)

some Etas estimated to be around 2 or 3, but since I am fitting a quite n=
oisy PD data,  I think they are actually reasonable no Etas close to 0=

 be taken out?   ________________________________ From: "Bac=
hman, William" <William.Bachman>; nmusers
PM Subject: RE: [NMusers] OMEGA selection Well, the first thing t=
hat I would do is look at the magnitude of the estimates of the etas.  I =
would eliminate those etas that are poorly estimated (essentially the very =
large values or those approaching zero). __________________________=
______ From: owner-nmusers] On Behalf Of Ethan Wu Sent: Wednesday, April 15, 2009 11:47 AM T=
o: nmusers
 all,   I am fitting a PD response, and the equation goes like this: =
total response = baseline+f(placebo response) +f(drug response) first, =
I tried full omega block, and model was able to converge, but $COV stop fai=
led. To me, this indicates that too many parameters in the model. The str=
ucture model is rather simple one, so I think probably too many Etas. I =
wonder is there a good principle of Eta reduction that I could implement =
here. Any good reference? ICON plc made the following annotations. -=
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in 18 Ireland Registered number: 145835
Received on Wed Apr 15 2009 - 13:15:12 EDT

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