Re: Minimization Terminated in Bootstrapping
Hi, Dr. Bonate:
Thank you very much for your comments. There are some more sparse data in
the data set and I wasn't aware that I should do stratification for
bootstrapping, so thank you for pointing it out.
Best regards,
Siwei
Quoted reply history
On Wed, Oct 29, 2014 at 11:58 AM, Bonate, Peter <[email protected]>
wrote:
> Not just yet. I’ve seen many people just naively bootstrap their
> dataset. It may be that your bootstrap datasets do not adequately
> represent model development dataset. For example suppose you had 75%
> sparse data and 25% rich data in your model development set. It is
> imperative that your bootstrap dataset maintain this ratio so you need to
> stratify by data richness. Otherwise you could get a bootstrap dataset that
> is predominantly sparse data which would not support such a complicated
> absorption model. The same holds true if there are important covariates in
> your model.
>
>
>
> pete
>
>
>
>
>
> Peter L. Bonate, PhD
>
> Senior Director
>
> Global Head - Pharmacokinetics, Modeling, and Simulation
>
> Global Clinical Pharmacology & Exploratory Development
>
>
>
> Astellas
>
> 1 Astellas Way, 2N.184
>
> Northbrook, Il 60062
>
> phone: 224-205-5855
>
> fax: 224-205-5914
>
> email: [email protected]
>
>
>
>
>
> *From:* [email protected] [mailto:[email protected]]
> *On Behalf Of *siwei Dai
> *Sent:* Tuesday, October 28, 2014 9:00 AM
> *To:* [email protected]
> *Subject:* [NMusers] Minimization Terminated in Bootstrapping
>
>
>
> Dear NM users:
>
>
>
> I have a data set where the absorption phase is highly variable. A
> complicated absorption model (the TRANSIT model) significantly improve the
> model fit (OFV drops over 250) compared to a 1st-order absorption model
> with lag time. The complicated final model converged and the covariance
> step was successful. The condition number is low (less than 10), although
> there were many runs with rounding errors during model development.
>
>
>
> However, in the bootstrap analysis,about 600 out of 1000 iterations had
> minimization terminated which leads to a successful rate of only 40%.
>
>
>
> My question is: is there any consensus regarding the acceptable successful
> rate for bootstrap analysis? I understand 40% is very low. Should I reject
> this model then?
>
>
>
> Any suggestions will be greatly appreciated.
>
>
> Thanks,
>
>
>
> Siwei
>