Re: CCV or Additive error models?
Yuanyue,
It is has been well established and discussed at length on nmusers that a successful $COV step says nothing about the suitability of the model to describe the data.
Quoted reply history
On the other hand the OFV is a very reliable statistic for model selection. You should use the combined error model.
Nick
On 1/07/2011 5:17 p.m., [email protected] wrote:
> Dear nmusers,
>
> In one of my PK analysis, if I chose Y=F+F*ERR(1)+ERR(2), I got lower
> objective value=1130.907, but $COV step failed (S matrix is singular);
> when I chose Y=F+ERR(1), I got $COV successful but higher objective
> value=1351.735. I prefer to choose the addivtive error model even if with
> higher objective value because it seems comfortable to see $COV
> successful. Can anyone give me other suggestions?
>
> Thanks
>
> Yuanyue (Paul) Gao
>
> 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