RE: t-distribution =scaled mixture of normal distributions

From: VPIOTROV@PRDBE.jnj.com Subject: [NMusers] RE: t-distribution =scaled mixture of normal distributions Date: Fri, 25 Jul 2003 10:22:14 +0200 Dear Yaning, I am not sure about other softwares. The two nonlinear mixed-effects program I used myself: nlme (in S-PLUS of R) and WinNonMix, are based on the normality assumption. As to NONMEM, the idea I introduced 3 years ago about the mixture of normals at the level of the residual error had no connection to the t-distribution. Moreover, the residual error distribution with an individual is still normal, and I do not know how to make it t-distributed. Best regards, Vladimir ----------------------------------------------------------------- Vladimir Piotrovsky, Ph.D. Research Fellow, Advanced PK-PD Modeling & Simulation Global Clinical Pharmacokinetics and Clinical Pharmacology (ext. 5463/151) Johnson & Johnson Pharmaceutical Research & Development Turnhoutseweg 30 B-2340 Beerse Belgium _______________________________________________________