RE: OFV by endpoint of joint models?
Hi Jeroen
I note your thought about CWRES and OFV. In some exploratory work, we did not
find that the rank order of abs(CIWRES) or CIWRES^2 and PHI() was preserved
(with FOCEI) for continuous data. I had anticipated some rank similarity.
Cheers
Steve
________________________________________
Stephen Duffull | Professor
Otago Pharmacometrics Group
School of Pharmacy | He Rau Kawakawa
University of Otago | Te Whare Wānanga o Otāgo
Dunedin | Ōtepoti
Aotearoa New Zealand
Ph: 64 3 479 5099
Quoted reply history
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of
Jeroen Elassaiss-Schaap (PD-value B.V.)
Sent: Tuesday, 11 October 2022 4:07 am
To: Matts Kågedal <[email protected]>; [email protected]
Subject: Re: [NMusers] OFV by endpoint of joint models?
Hi Matts,
The easiest way to assess is when one of two endpoints is modeled directly
(TTE, logistic regression) as often is the case, than look at the Y value for
those endpoints, as reported in the PRED variable. The sum of those values is
the ofv, or proportional to it, for that particular endpoint - the other
endpoint is than affected in the inverse way.
If you have multiple continuous endpoints it becomes more complicated.
You could either look at the sum of absolute CWRES to get an idea, but not
exact in terms of ofv comparison. Another approximate comparison would be to
run the model without evaluation (e.g. MAXEVAL=0) with the original msfofile as
$MSFI for the separate endpoints (by e.g.
IGN(DVID.NE.x) where x is your endpoint). It is not exact, again, as it
ignores the correlation between endpoints but should get you in the
neighborhood. As an improvement to this method you could force evaluation at
the original posthocs by reading them in in your datafile
- this would still ignore correlation but the effect would be largely
diminished because the posthocs are fixed to those estimated with correlation.
Hope this helps,
Jeroen
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On 10-10-2022 16:03, Matts Kågedal wrote:
> Hi all,
> I have a question related to the objective function value when
> multiple endpoints are modelled jointly. Specifically I would like to
> know if a change in in OFV between models is driven primarily by one
> of the endpoints or if both contributes to the change, or maybe they
> are even driving the OFV in oposite directions.
>
> Is there a way to get some form of partial OFV by endpoint?
> Best regards,
> Matts