RE: simulation
From: Xiaofeng Wang - xiaofeng.wang@bms.com
Subject: RE: [NMusers] simulation
Date: 1/27/2004 2:14 PM
Hi Ken:
Thank you for message and elaboration of the question I have.
yes, you are right that I was asking for the SEs for the IPREDs.
I tried to go in this direction:
for example, from FO, the PK model can be linearized as yij=fi(Theta1, ...)
+gij etai +hij epij, where gij is the partial derivative of the model at etai=0.
then the variance of yij is G'i Omega Gi +diag (Hi'Sigma Hi). If I have
the PK model, the covariate model, as well as Omega and Sigma, the
variance (or SEs) of yij can be calculated and then the 95% CI of yij.
From NONMEN manual, the matrix G and H can be obtained when running
estimation (I don't know how to write the code to get these two matrix,
if anyone can point it out for me). I dont' know in the simulation mode,
if G and H can be also obtained. In fact, H is easy to obtained once the
error model was determined. However, G is involved the estimate of all
the partial derivative at eta.
xiaofeng