RE: Centering (was Re: Missing covariates)

From: "Bachman, William" <bachmanw@globomax.com> Subject: RE: Centering (was Re: Missing covariates) Date: Thu, 5 Jul 2001 11:32:52 -0400 Diane, I think your statement requires a little clarification. The choice of centering value depends on the clinical situation, UP TO A POINT. In the extreme, one should probably not use a centering value of 65 years for a model developed in twenty year olds. It would neither be logical nor you would gain the numerical stability due to centering near a mean or median. I feel much more comfortable in situations using a "nominal" centering value not too distant from the central tendency (eg. 70 kg for study in adults, etc.) Bill