Re: Centering (was Re: Missing covariates)

From: "diane r mould" <drmould@attglobal.net> Subject: Re: Centering (was Re: Missing covariates) Date: Tue, 3 Jul 2001 18:58:27 -0400 Alan I think that the variable used for centering should be based on a clinically relevant value rather than means or medians. if, for example, the mean age of a data set is 50 years, but the drug is designated for use with a patients who are actually older (say, 65 years) then you may wish to consider centering parameters based on the expected use of the drug rather than a statistic from a contrived study. So in a nutshell, I believe that the choice of value for centering or normalizing a parameter depends on the clinical situation. However, I do agree with the previous comments about the numerical improvements expected from centering or normalization. hope that this helps diane