RE: Covariate effect

From:"Kowalski, Ken" Subject: RE: [NMusers] Covariate effect Date:Mon, 10 Mar 2003 10:04:01 -0500 Toufigh, It is likely that you have substantial power to detect relatively small differences in the covariate effect. This occurs quite frequently with continuous covariates like body weight when you have a lot of subjects and a wide range of values. Since the change in OFV is the yardstick we use to determine statistical significance of the covariate effects, I wouldn't discard it and exclude the covariate effect from the model simply because it doesn't appear to be clinically relevant. I would use clinical relevance only to intrepet the parameters for the final model and their impact on dosing. I would not use a clinical relevance assessment to guide model building as this can be very subjective (based on one's assessment of what is clinically relevant for each covariate effect). Ken _______________________________________________________