.stand...@nhs.net; 'Jeroen Elassaiss-Schaap'
Ämne: RE: [NMusers] OMEGA matrix
Hi All,
I agree with everything that Marc and Douglas have pointed out. I too do not
advise building the omega structure based on repeated likelihood ratio tests.
The approach I take is more akin to
: Gastonguay, Marc [mailto:ma...@metruminstitute.org]
Sent: Thursday, October 02, 2014 7:03 AM
To: Eleveld, DJ; nmusers@globomaxnm.com; ken.kowal...@a2pg.com;
non...@optonline.net; joseph.stand...@nhs.net; Jeroen Elassaiss-Schaap
Subject: Re: [NMusers] OMEGA matrix
Douglas makes important
Douglas makes important point in this discussion. That is, the method used
to judge parsimony of the model must consider the performance of the model
for intended purpose.
Consider the parsimony principle: "all things being equal, choose the
simpler model". The key is in how to judge the first par
; Eleveld, DJ
Onderwerp: Re: [NMusers] OMEGA matrix
Dear Pavel, others,
The underlying technical difference is that SAEM is in its core a sampling
methodology. Off-diagonal elements (as explained by Bob Bauer) are available as
sample correlations and do not have to be separately computed in contrast
...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On
Behalf Of Nick Holford
Sent: Tuesday, September 30, 2014 4:51 PM
To: nmusers
Subject: Re: [NMusers] OMEGA matrix
Hi,
As pointed out by others I agree it is essential to consider the existence of
random effect correlations if you wish
Pavel,
[Apologies if this appears for a 3rd time on nmusers - I sent it earlier
but it did not show up yet]
You made some remarks about NONMEM and Monolix which I don't fully
understand.
You wrote "Monolix allows us to set a single correlation to zero.
NONMEM may require a different approac
relations. A discussion along those lines in reporting seems the
>more
>fruitful to me.
>
>Best regards,
>Jeroen
>
>http://pd-value.com <http://pd-value.com/>
>
>
>-- More value out of your data!
>
>
>
>
>-Original Message-
>From: owner
us...@globomaxnm.com
[mailto:owner-nmus...@globomaxnm.com] *On Behalf Of *Jeroen
Elassaiss-Schaap
*Sent:* Monday, September 29, 2014 7:00 PM
*To:* ken.kowal...@a2pg.com; nmusers@globomaxnm.com;
joseph.stand...@nhs.net; non...@optonline.net; d.j.elev...@umcg.nl
*Subject:* Re: [NMusers] OME
] On
Behalf Of Jeroen Elassaiss-Schaap
Sent: Monday, September 29, 2014 7:00 PM
To: ken.kowal...@a2pg.com; nmusers@globomaxnm.com; joseph.stand...@nhs.net;
non...@optonline.net; d.j.elev...@umcg.nl
Subject: Re: [NMusers] OMEGA matrix
Dear Pavel, others,
The underlying technical difference is
er-nmus...@globomaxnm.com> ] On Behalf Of Standing Joseph
(GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS FOUNDATION TRUST)
Sent: Friday, September 26, 2014 09:15
To: Kowalski, Ken; 'Eleveld, DJ'; 'Pavel Belo'; nmusers@globomaxnm.com
<mailto:nmusers@globomaxnm.com>
Su
h
(GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS FOUNDATION TRUST)
Sent: Friday, September 26, 2014 09:15
To: Kowalski, Ken; 'Eleveld, DJ'; 'Pavel Belo'; nmusers@globomaxnm.com
<mailto:nmusers@globomaxnm.com>
Subject: RE: [NMusers] OMEGA matrix
Dear Pavel,
To answer your
DATION TRUST)
> Sent: Friday, September 26, 2014 09:15
> To: Kowalski, Ken; 'Eleveld, DJ'; 'Pavel Belo'; nmusers@globomaxnm.com
> Subject: RE: [NMusers] OMEGA matrix
>
> Dear Pavel,
>
> To answer your question I suggest you go on Bob Bauer's NONMEM
leveld, DJ'; 'Pavel Belo'; nmusers@globomaxnm.com
Subject: RE: [NMusers] OMEGA matrix
Warning: This message contains unverified links which may not be safe. You
should only click links if you are sure they are from a trusted source.
Hi Douglas,
My own thinking is that you sho
sday, September 25, 2014 4:36 PM
To: Pavel Belo; nmusers@globomaxnm.com
Subject: RE: [NMusers] OMEGA matrix
Hi Pavel,
My question is: Why is it desirable to fit a complete omega matrix if its
physical interpretation is unclear? Etas are variation of unknown origin
i.e. not explained by the structural m
Hi Pavel,
My question is: Why is it desirable to fit a complete omega matrix if its
physical interpretation is unclear? Etas are variation of unknown origin i.e.
not explained by the structural model. A full omega matrix allows the unknown
variation of one paramater to have a (linear?) relations
at
guarantee "legal" matrices.
Steve
> -Original Message-
> From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On
> Behalf Of Bob Leary
> Sent: Friday, 15 June 2012 5:11 a.m.
> To: Bauer, Robert; Matt Hutmacher; 'Nick Holford'; nmuse
; -Original Message-
> From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On
> Behalf Of Bob Leary
> Sent: Friday, 15 June 2012 5:11 a.m.
> To: Bauer, Robert; Matt Hutmacher; 'Nick Holford'; nmusers@globomaxnm.com
> Subject: RE: [NMuse
m: owner-nmus...@globomaxnm.com [owner-nmus...@globomaxnm.com] On Behalf Of
Bauer, Robert [robert.ba...@iconplc.com]
Sent: Wednesday, June 13, 2012 4:05 PM
To: Matt Hutmacher; 'Nick Holford'; nmusers@globomaxnm.com
Subject: RE: [NMusers] omega matrix - friendly suggestion
Thank you all for your
et(A)=-0.512.
Siva
From: owner-nmus...@globomaxnm.com [owner-nmus...@globomaxnm.com] On Behalf Of
Matt Hutmacher [matt.hutmac...@a2pg.com]
Sent: Wednesday, June 13, 2012 2:35 PM
To: 'Nick Holford'; nmusers@globomaxnm.com
Subject: RE: [NMusers] omega matrix - friendly suggestio
Wednesday, June 13, 2012 2:35 PM
To: 'Nick Holford'; nmusers@globomaxnm.com
Subject: RE: [NMusers] omega matrix - friendly suggestion
Dear Paolo, Nick, all,
A way to ensure a nonnegative definite (NND) variance-covariance matrix is
to use a Cholesky decomposition of the matrix (Ref
: Wednesday, June 13, 2012 1:20 PM
To: nmusers@globomaxnm.com
Subject: Re: [NMusers] omega matrix - friendly suggestion
Paolo,
You may remember this discussion about the history of the correlation
feature for OMEGA (and SIGMA) blocks.
http://www.cognigencorp.com/nonmem/current/2009-July/1804.html
IMHO the
Paolo,
You may remember this discussion about the history of the correlation
feature for OMEGA (and SIGMA) blocks.
http://www.cognigencorp.com/nonmem/current/2009-July/1804.html
IMHO the only sensible way for a human to write a covariance matrix is
using the SD and correlation style introduce
Dear Pavel and Ken,
I also share the same pain, especially when coding correlations for
between-occasion variability ETAs. This implies reorganizing them in
blocks and renumbering everything. A real chore, and a very error-prone
process.
Maybe one can think of using the OMEGA in the correlati
Dear Pavel,
I certainly feel your pain but you have to be careful how you fix certain
elements in Omega to ensure that you have a valid positive definite
covariance matrix. The starting values in your $OMEGA block do not give
rise to a valid covariance matrix. Note in particular that the cova
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