Re: Nested random effects with NONMEM?

From: "Pascal Girard" <PGIRARD@pharsight.com> Subject: Re: Nested random effects with NONMEM? Date: Mon, 13 Mar 2000 22:58:37 +0100 Some time ago, Vladimir Piotrovski. indicated that nlme Splus function new release (also available in freeware R) could handle nested random effects. Because of the limitations of NONMEM indicated by Lewis, Silvy Laporte and myself tested nlme via different simulations using 3 and 4 random nested models. We found that 3 (and even more) nested levels was easy to implement, except that you need to write your PK model. Results was very close from the one we got with NONMEM using the implementation suggested by Lewis. For models with 4 nested random effects that NONMEM could not handle we found, using simulations, unbiased and precise results with nlme. In addition nlme appeared very fast even with this complex variance structure. Pascal Girard pgirard@pharsight.com