Re: covariate significance

From: Nick Holford Subject: Re: [NMusers] covariate significance Date: Fri, 19 Apr 2002 09:09:44 +1200 Jorn, My decision would be guided more by the biological/mechanistic plausibility of considering the covariate as a dichotomous variable (choice 1) or a continuous scale variable (choice 2). I would certainly want to try a model with an extra parameter to test for each of the 3 values of X having its own independent effect on THETA(1) if the biology was compatible. Biology is about studying the signal. Statistics is about studying the noise. I find signal based decisions more satisfying than those based on reducing the noise. Nick Nick Holford, Divn Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x6730 fax:373-7556 http://www.phm.auckland.ac.nz/Staff/NHolford/nholford.htm