NONMEM Users Network Archive

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Re: FW: PPC

From: Leonid Gibiansky <LGibiansky>
Date: Fri, 25 Jul 2008 19:14:49 -0400

I cannot make any general statements but here is the summary of the 13
different models that I tested for comparison of bootstrap and nonmem CI.

http://www.quantpharm.com/pdf_files/2572-GibianskyPage2007Poster2007final.pdf

Note that all bootstrap samples were appropriately stratified by major
covariates (such as study, dose, weight as necessary, etc.).

Leonid

--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566




makamal
> Dear Dr. Holford,
> Please correct me if I am wrong, however my understanding is that
> asymptotic distribution implied by NONMEM's covariance step approaches
> normality as the sample size gets larger or we have more data. However,
> a non parametric bootstrap distribution may have poor coverage with a
> small sample size as well, since it relies on sampling subjects with
> repalcement in the data set. So both distributions have problems when
> sample size is small (e.g. N<30). Therefore I would think when N is
> large the wald based Confidence Intervals from NONMEM are appropriate
> enough. It would be helpful to know the criteria when generating a non
> parametric bootstrap distribution is really advantageous.
> Thanks, Mohamed
> Quoting Nick Holford <n.holford
Received on Fri Jul 25 2008 - 19:14:49 EDT

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