RE: Pharsight Simulations

From: michael_looby@sandwich.pfizer.com Subject: RE: Pharsight Simulations Date: Mon, 15 Nov 1999 12:30:03 -0000 Dear Users I am not sure what problem Eliane has encountered, but I have had an irritating problem with simulation in the Pharsight product. In the Pharshight trial designer, the log normal distribution simulation option expects you (for some strange reason) to enter the arithmetic mean rather than the geometric mean of your (log normal) distribution (In the manual it just says enter the mean of the log normal distribution!!). This does not make much sense since the geometric mean is the natural location parameter of this distribution and is in contrast to most other simulation packages. While incorrectly entering the geometric mean in the Pharsight package, I only noticed the problem when I was simulating parameters with large variability where the arithmetic and geometric mean start to differ significantly. It subsequently took me considerable time and effort to source the problem. This is perhaps a nice illustration of what can go wrong in simulation studies, particularly when you are unfamiliar with the software. Regards Michael Looby PhD Clinical Project Manager Pfizer Central Research, Sandwich Kent CT13 9NJ, UK Tel: +44 1304 648978 Fax: +44 1304 658159 Email: michael_looby@sandwich.pfizer.com