RE: WRES AND OUTLIER IDENTIFICATION/EXCLUSION

From: Nick Holford n.holford@auckland.ac.nz Subject: RE: [NMusers] WRES AND OUTLIER IDENTIFICATION/EXCLUSION Date: Mon, 02 Oct 2006 12:59:33 +1300 Mats, Ken, I must be missing some subtle issue here -- why do you think it is necessary to code this using -2LL? Why not code it like this? $THETA (0,0.1,1) ; P prob of being an outlier (0,1,) ; SD of additive residual error (0,1,) ; K fractional difference in SD in outlier population $OMEGA 0.5 ; between subject variability in MYPRED $SIGMA 1 FIX ; unit random effect $MIX NSPOP=2 P(1)=THETA(1) ; P prob of being an outlier P(2)=1-P(1) $PRED ;MYPRED= ...any PKPD model you like with random effects e.g. MYPRED=DOSE/V*EXP(-CL/V*TIME)+ETA(1) ;SD= ... any residual error model you want expressed with THETAs e.g SD=THETA(2) ; additive residual error SD IF (MIXNUM.EQ.1) THEN ; outlier KOUT=THETA(3) ELSE KOUT=1 ENDIF Y=MYPRED+KOUT*SD*EPS(1) Nick -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556 http://www.health.auckland.ac.nz/pharmacology/staff/nholford/