Re: Question: FO VS. FOCE VS. FOCE-INTER in POSTHOC 2014-1-3
Zhao,
For more details you can look at Nonmem help and manuals. POSTHOC step
of FO and MAXEVAL=0 of FOCE will do exactly the same computations (given
the population parameters, will compute individual parameters and
predictions). INTERACTION options allows a more precise interpretation
of the error model (from help: with INTER option, "The dependence on
etas of the model for intra-individual random error is preserved in the
computation of the objective function" while without it, the program
"set etas to 0 during the computation of the model for
intraindividual random error")
Leonid
--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566
Quoted reply history
On 1/6/2014 6:53 AM, 赵赵 wrote:
> Dear Dr Leonid，
>
> Thanks so much! Your answer gave me a very clear direction of what to do
> next. Still, I just wonder the reason,the principle behind it. Would you
> please give me a further explanation?
>
> Thanks in advance
>
> Regards,
> Zhao
>
> > Date: Sun, 5 Jan 2014 10:56:17 -0500
> > From: [email protected]
> > To: [email protected]; [email protected]
> > Subject: Re: [NMusers] Question: FO VS. FOCE VS. FOCE-INTER in
> POSTHOC 2014-1-3
> >
> > Zhao,
> >
> > For MAXEVAL=0, FOCE and FO should provide identical results (POSTHOC is
> > needed for FO; for FOCE it is not necessary but you can use it as well).
> > Concerning INTER, it should be used in all cases except when the error
> > is purely additive (and you can use it even for additive error, this
> > should not affect your solution). So if you need POSTHOC run, the
> > recommendation is to use
> >
> > $ESTIMATION MAXEVAL=0 METHOD=1 INTER NOABORT POSTHOC
> >
> > in all cases. For external validation, VPC-style diagnostics (as well as
> > regular model diagnostic plots) would be preferable to the overall
> > measures like MPE or RMSE that are more or less useless in identifying
> > the direction of the bias (if you have any differences with the
> > literature models).
> >
> > Leonid
> >
> >
> > --------------------------------------
> > Leonid Gibiansky, Ph.D.
> > President, QuantPharm LLC
> > web: www.quantpharm.com
> > e-mail: LGibiansky at quantpharm.com
> > tel: (301) 767 5566
> >
> >
> >
> > On 1/4/2014 9:31 PM, 赵赵 wrote:
> > > Dear all,
> > >
> > > First of all, I wanna say HAPPY NEW YEAR to you guys. Best Wishes in
> > > this very beginning day of the "Horse Year"(Chinese calendar lol )
> > >
> > > Well,as titled, here is the question:
> > >
> > > I'm now doing external validation of the PPK models pubished before by
> > > other groups with my own data. Ｉfind extreme differences in MPE(mean
> > > prediction error), RMSE(root of mean squared prediction error) and
> so on
> > > while using different estimation methods like FO, FOCE, or FOCE-INTER,
> > > especially the one with interaction from the former 2.
> > >
> > > I do understand the diversity in these 3 methods. But how much is the
> > > influence as to POSTHOC in external validation. For example:
> > >
> > > $ESTIMATION MAXEVAL=0 METHOD=1 NOABORT POSTHOC
> > >
> > > Could anybody explain to me and clarify the problem?
> > >
> > > Great thanks!
> > >
> > > Yours
> > >
> > > Zhao Chenyan
> > >
> > > Department of Clinical Pharmacy, Huashan Hospital, Fudan University,
> > > Shanghai, P.R.China
> > >