RE: t-distribution in NONMEM?

From: VPIOTROV@PRDBE.jnj.com Subject: RE: [NMusers] t-distribution in NONMEM? Date: Thu, 24 Jul 2003 15:25:04 +0200 Yaning, To the best of my knowledge, you cannot use t-distribution in NONMEM. At least, I cannot recall any easy way to do it for estimation. There is, however, an approach that allows to improve the fit in case of heavily tailed distributions of observations. It is based on the assumption that the study population is not homogeneous, but includes groups of individuals which differ in their residual variability. This can be implemented using $MIX option of NONMEM. An example can be found in the NONMEM users archive ( http://www.cognigencorp.com/nonmem/nm/99aug102000.html). This is also applicable to the situation of heavy-tailed distribution of PK parameters, say, CL. 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