RE: Non-physiological parameters at lowest OBJ
From: Ken Kowalski <Ken.Kowalski@pfizer.com>
Subject: RE: [NMusers] Non-physiological parameters at lowest OBJ
Date: 8/6/2003 8:01 AM
Justin,
With Case 1 you're getting flip-flop with ka < ke=CL/V. You might consider
constraining your model so that the population estimate of ka > ke. You can
do this with something like:
TVCL=THETA(1)
TVV=THETA(2)
TVKE=TVCL/TVV
TVKA=TVKE+THETA(3)
CL=TVCL*EXP(ETA(1))
etc.
where the thetas are all bounded >0. Others may know of a way to ensure
against flip-flop of the individual-specific parameters as well (i.e.,
involving the etas)...can anyone comment? Hopefully, with these constraints
you will find an optimum with the same OBJ as Case 1 but with more
reasonable parameters.
Ken