RE: re: bug in NONMEM VI?

From: John Lukas Sent: Mon 12/17/2007 11:51 PM To: [email protected] Subject: re: bug in NONMEM VI? Dear Nmusers, A simple LME model run using NM version VI, FO method, with 4 covariates (5 THETA's) as, . . $PRED SUM1=THETA(2)*COV1+THETA(3)*COV2 SUM2=THETA(4)*COV4+THETA(5)*COV3 TLAU=THETA(1)+SUM1+SUM2 F=TLAU+ETA(1) Y=F+EPS(1) $THETA 4 .1 .1 .1 .1 $OMEGA .1 $SIGMA .1 $ESTIMATION MAXEVALS=1900 PRINT=5 METHOD=0 (let's call this FIT A) gave a different fit from another (FIT B) where only the order of THETA( 4) and 5 was reversed, all else kept the same, as, . . SUM2=THETA(5)*COV4+THETA(4)*COV3 . . (even more strange, FIT B, the reversed order run, proved to be the good run!) NONMEM version V had the same result for both FITS A and B, as expected (and same as FIT B from version 6). FOCE gave good answers always in both NONMEM version V and version VI. But, the question remains about that dependence on ordering of the THETAs with the FO method for version VI. Any comments? Has there been discussion on this earlier that I missed? Thanks in advance. John PS I am aware of other *important* incosistencies between version VI and V from university colleagues working on a PK problem with FOCE... John C Lukas Strategic Consulting Services Pharsight Corp. line: + 33 492 726 495 cell: + 33 626 496 777