Re: Reducing ETAs actually decreased OFV
Dear Leonid,
I tried with your method and found the same result. The initial estimation
of the added ETA was set at 0.01, and the result showed an increase of OFV.
Please see below the $PK part of the control file for more information.
Many thanks.
Dear Bill,
Could you please explain that in a little bit more detail? I am pasting the
$PK part of the control file in case you could find the useful information.
Thanks a lot.
$PK
FA1=0
FA2=0
FA3=0
FA4=0
IF(DOSE.EQ.250) THEN
FA1=1
ENDIF
IF(DOSE.EQ.500) THEN
FA2=1
ENDIF
IF(DOSE.EQ.850) THEN
FA3=1
ENDIF
IF(DOSE.EQ.1000) THEN
FA4=1
ENDIF
F1=FA1+FA2*THETA(6)+FA3*THETA(7)+FA4*THETA(8)
TVCL=THETA(1)
TVV2=THETA(2)
TVKA=THETA(3)
TVQ=THETA(4)
TVV3=THETA(5)
CL=TVCL*EXP(ETA(1))
V2=TVV2*EXP(ETA(2))
KA=TVKA*EXP(ETA(5))
Q=TVQ*EXP(ETA(3))
V3=TVV3*EXP(ETA(4))
S2=V2/1000
S3=V3/1000
$ERROR
IPRE=F
IRES=DV-IPRE
W=F
IF(W.EQ.0) W = 1
IWRE = IRES/W
Y=F*(1+EPS(1))+EPS(2)
Best Regards
Quoted reply history
On 12 August 2013 20:50, Denney, William S. <[email protected]>wrote:
> Hi Xinting,
>
> In a few rare cases, I've seen this happen if the model is approaching
> nonconvergence. In those cases, typically the RSE on one or more
> parameters will increase and the ratio of max to min eigenvalues will
> increase substantially. Are you seeing either of these?
>
> Thanks,
>
> Bill
>
> On Aug 11, 2013, at 21:56, "Leonid Gibiansky" <[email protected]>
> wrote:
>
> Xinting,
> Try to start from the initial conditions of your "reduced" model but add
> that "reduced" ETA with the corresponding OMEGA equal to 0.01 or other
> small number. If the control stream code is correct, the objective function
> should decrease or retain the same value.
> Leonid
>
> --------------------------------------
> Leonid Gibiansky, Ph.D.
> President, QuantPharm LLC
> web: www.quantpharm.com
> e-mail: LGibiansky at quantpharm.com
> tel: (301) 767 5566
>
>
>
> On 8/10/2013 10:23 PM, Xinting Wang wrote:
> > Dear all,
> >
> > Does anyone witnessed such a phenomenon in NONMEM as when you reduced an
> > ETA, the OFV value, rather than increase, actually decreased? It's quite
> > against intuition, as individual estimation should be better than
> > population estimation in that particular parameter. Both models, whether
> > having this ETA, converged very well.
> >
> > Best
> >
> > --
> > Xinting
>
--
Xinting