RE: Why should we avoid using micro rate constants?
Hi All,
It could also be the statistical model. If you are estimating 4 parameters then different parameterisations should be fairly equivalent if a BLOCK(4) structure is used for both parameterisations. If only the diagonal option is used, then this could be why different results/minimisations are obtained for different parameterisations.
Kind regards,
Janet
Janet R Wade, PhD
Occams
Senior Consultant
Quoted reply history
From: owner-nmusers_at_globomaxnm.com <owner-nmusers_at_globomaxnm.com> On Behalf Of Leonid Gibiansky
Sent: 04 February 2019 07:30
To: Singla, Sumeet K <sumeet-singla_at_uiowa.edu>
Cc: nmusers_at_globomaxnm.com
Subject: Re: [NMusers] Why should we avoid using micro rate constants?
It could be just coding error, could you show the control stream?
Thanks
Leonid
On Feb 3, 2019, at 12:44 PM, Singla, Sumeet K <sumeet-singla_at_uiowa.edu <mailto:sumeet-singla_at_uiowa.edu> > wrote:
Hello everyone!
I have a question. I was trying to build a 2-compartment PK model for marijuana use in occasional and chronic smokers. Initially, I was using providing rate constants K12 and K21 in PK block and it resulted in poor fitting. Then, I later changed to CL,V1, V2 , Q and it resulted in proper fitting. I was perplexed as to why I couldn’t get a proper fit by providing rate constants? I tried to look online but couldn’t find any proper explanation about when (or not) we should use micro constants in PK block to define our model in NONMEM? Does anyone has any useful insights into this?
Regards,
Sumeet Singla
Graduate Student
Dpt. of Pharmaceutics & Translational Therapeutics
College of Pharmacy- University of Iowa