RE: Minimization Terminated in Bootstrapping
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]
Quoted reply history
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