Hi,
The OFV is computed using all observations. If you imagine an
observation at time 0 then it will change the OFV. So my advice is not
to imagine concentrations with MDV=0 but just use the concentrations you
really measured.
Nick
ke fang wrote:
> Hi!
> Dear all!
> My samples were collected after a single intramuscular injection. One
> individuals provies only one tissue samples within the whole study. I found
> the MOFV were quite different between the MDV was used or not.
>
> In my opinion, the concentration in tissue at T0 must be 0 because of the
> intramuscular administration. So the concentration at T0 was not a real
> observed 0 but a assumed 0. The question was that if i treated the T0
> concentration as a MDV, the MOFV was quite different from treating it as a
> real obesrved concentration.
>
> Whether the MDV should be used in my case? Can anyone help me with this
> problem?
>
> Thanks in advance!
>
>
> Fang Ke
>
>
> ___________________________________________________________
> 好玩贺卡等你发，邮箱贺卡全新上线！
> http://card.mail.cn.yahoo.com/
>
--
Nick Holford, Dept Pharmacology & Clinical Pharmacology
University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand
[email protected] tel:+64(9)923-6730 fax:+64(9)373-7090
mobile: +33 64 271-6369 (Apr 6-Jul 17 2009)
http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford
Imaginary concentrations
Hi,
The MDV=1 implies that your observation at that time point is missing. Zero is
not the same as missing information and will contribute to the MOFV.Whether you
treat the observation as zero (which makes sense for a non-endogenous analyte)
or you exclude that (assumed) observation/time point altogether from your
dataset should not affect your PK parameter estimates significantly. The latter
approach may be the way to go..
Just my 2 cents!
Regards,
J.O.
> Date: Mon, 13 Apr 2009 22:24:29 +0800
> From: [email protected]
> To: [email protected]
> Subject:
>
>
> Hi!
> Dear all!
> My samples were collected after a single intramuscular injection. One
> individuals provies only one tissue samples within the whole study. I found
> the MOFV were quite different between the MDV was used or not.
>
> In my opinion, the concentration in tissue at T0 must be 0 because of the
> intramuscular administration. So the concentration at T0 was not a real
> observed 0 but a assumed 0. The question was that if i treated the T0
> concentration as a MDV, the MOFV was quite different from treating it as a
> real obesrved concentration.
>
> Whether the MDV should be used in my case? Can anyone help me with this
> problem?
>
> Thanks in advance!
>
>
> Fang Ke
>
>
> ___________________________________________________________
> 好玩贺卡等你发，邮箱贺卡全新上线！
> http://card.mail.cn.yahoo.com/
--- On Mon, 4/13/09, Nick Holford <[email protected]> wrote:
Quoted reply history
> From: Nick Holford <[email protected]>
> Subject: [NMusers] Re: Imaginary concentrations
> To: [email protected]
> Date: Monday, April 13, 2009, 11:55 PM
> Hi,
>
> The OFV is computed using all observations. If you imagine
> an
> observation at time 0 then it will change the OFV. So my
> advice is not
> to imagine concentrations with MDV=0 but just use the
> concentrations you
> really measured.
>
> Nick
>
> ke fang wrote:
> > Hi!
> > Dear all!
> > My samples were collected after a single intramuscular
> injection. One individuals provies only one tissue samples
> within the whole study. I found the MOFV were quite
> different between the MDV was used or not.
> >
> > In my opinion, the concentration in tissue at T0 must
> be 0 because of the intramuscular administration. So the
> concentration at T0 was not a real observed 0 but a assumed
> 0. The question was that if i treated the T0 concentration
> as a MDV, the MOFV was quite different from treating it as a
> real obesrved concentration.
> >
> > Whether the MDV should be used in my case? Can anyone
> help me with this problem?
> >
> > Thanks in advance!
> >
> >
> > Fang Ke
> >
> >
> >
> >
>
> --
> Nick Holford, Dept Pharmacology & Clinical
> Pharmacology
> University of Auckland, 85 Park Rd, Private Bag 92019,
> Auckland, New Zealand
> [email protected]
> tel:+64(9)923-6730 fax:+64(9)373-7090
> mobile: +33 64 271-6369 (Apr 6-Jul 17 2009)
> http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford
>
>
>
Thanks to all!
I've go thourgh the guide book of NONMEM and found the EVID term could seperate
the dose from observation event. So i need not to use the MDV term.