From:Venkatesh Atul Bhattaram
Subject: Integrator option
Date: Thursday January 10, 2002 23:30
 
Hello All. 
Could somebody share his experience on this! I am trying to develop a pk model for a drug
which exhibits complex absorption characteristics using differential equations. I am using a
software SCIENTIST in which the user has an option to select the integrator method.
I was observing that when I was using Eulers method the final estimates did not
make any meaning (some estimates were as high as 10000). But when I used EPISODE
STIFF option the estimates were making meaning. Also I observe a goo decrease the
sum of squares (least squares estimation). I was wondering why this could be. Also
how will the reliability of the estimates might be? 

Thanks in advance 

Venkatesh Atul Bhattaram
Post-doctoral fellow
University of Florida
Gainesville-32601 
ph: 352-846-3257

******

From: Piotrovskij, Vladimir
Subject: Integrator option
Date: Fri, 11 Jan 2002 08:57:48 +0100

Atul, 
Euler method is very rough, you'd better not use it for estimation. 
Best regards,
Vladimir
----------------------------------------------------------------Vladimir
Piotrovsky, Ph.D.Research Fellow, Advanced PK-PD Modeling & Simulation
Global Clinical Pharmacokinetics and Clinical Pharmacology
(ext. 5463/151)
Johnson & Johnson Pharmaceutical Research & Development
Turnhoutseweg 30B-2340 
BeerseBelgium
Fax: (+3214)605834
Email: vpiotrov@janbe.jnj.com