Re: Problems with an apparent compiler-senstive model
From: "Tsai, Max" max.tsai@spcorp.com
Subject: Re: [NMusers] Problems with an apparent compiler-senstive model
Date: Sun, 30 Jul 2006 15:23:43 -0400
Nick,
Let me provide some additional details for clarity. I often encounter floating point error
messages for which no final parameter estimates are provided in the output for comparisons.
Comparing the gradients of the two separate runs using the same initial estimates, both seem
to travel the same path initially. After 10-20 iterations, the paths diverge where one run
appears to reach a minima and the other run encounters problems with numerical integration.
In attempts to "guide" the model in the right direction, I used the final estimates of the
successful run as initial estimates for the run on the troublesome compiler without any luck
(same floating point error). If parameter estimates are reasonable and model performance
(predictive check) seems adequate for this model, would you still use this model as a basis
for simulations, even though it does not run consistently?
-Max
Max Tsai, Ph.D.
Associate Principal Scientist (DMPK)
Schering-Plough Corporation
2015 Galloping Hill Road
K-15-2-2650
Kenilworth, NJ 07033-0530
(: (908) 740-3911
: (908) 740-2916
*: max.tsai@spcorp.com