Dear nmusers,
A question for the autocovariate (nmac.bat in WFN): Don't we need to
adjust the initials for each covariate entering into the base model? As my
understanding, when a new covariate entering a model, the initials should
be also adjusted to get the lowest OFV, otherwise we may not get the
global minimum. Or maybe nmac.bat can automatically adjust the initials?
Or we don't need to adjust the initials for each new covariate?
Any comment is much appreciated.
Paul
School of Pharmacy
University of Pittsburgh
716 Salk Hall
3501 Terrace Street
Pittsburgh, PA 15261
Phone: 412-648-8546
E-mail: [email protected]
initials for autocovariate
Paul,
IMHO automated covariate searching is not a good idea. It exists as a historical relic in WFN.
I'd suggest using your brain and knowledge of biology rather than automated searches for the Holy Grail.
If NONMEM did a good job of searching for the covariate parameters then you don't have to worry about initial estimates. Most covariate models have linear or almost linear parameters so NONMEM in fact usually does OK.
Nick
Quoted reply history
On 18/03/2011 5:20 p.m., [email protected] wrote:
> Dear nmusers,
>
> A question for the autocovariate (nmac.bat in WFN): Don't we need to
> adjust the initials for each covariate entering into the base model? As my
> understanding, when a new covariate entering a model, the initials should
> be also adjusted to get the lowest OFV, otherwise we may not get the
> global minimum. Or maybe nmac.bat can automatically adjust the initials?
> Or we don't need to adjust the initials for each new covariate?
>
> Any comment is much appreciated.
>
> Paul
>
> School of Pharmacy
> University of Pittsburgh
> 716 Salk Hall
> 3501 Terrace Street
> Pittsburgh, PA 15261
> Phone: 412-648-8546
> E-mail: [email protected]
--
Nick Holford, Professor Clinical Pharmacology
Dept Pharmacology& Clinical Pharmacology
University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
tel:+64(9)923-6730 fax:+64(9)373-7090 mobile:+64(21)46 23 53
email: [email protected]
http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford