Re: more on PREDvsDV

From: Chuanpu Hu 301-827-3210 FAX 301-480-2825 <HUC@cder.fda.gov> Subject: Re: more on PREDvsDV Date: Tue, 02 Feb 1999 09:42:14 -0500 (EDT) I share with Mats' belief that a regression line/smooth in the DV versus PRED plot, not PRED vs. DV, is a more sensible choice. The reason is that the assumption in a regression line is that the "x variable" is fixed, and the "y variable" has errors, not vice versa. It seems to me that using PRED vs. DV may have historical reasons. The S-plus nonlinear mixed effect routine NLME plots DV versus PRED, among other diagnostic plots. I often find myself turn the PRED vs. DV plot up side down in my head. Chuanpu ---------------------------------------------- Chuanpu Hu, Ph.D. Quantitative Methods and Research Food and Drug Administration Room 15B-45 5600 Fishers Lane (HFD-705) Rockville, MD 20857 Phone: (301)827-3210 Fax: (301)480-2825