Hi Laureen, If you want an objective second opinion then make likelihood profiles for both models. I expect a very shallow one for at least one maybe two parameters for the 3-compartment model and thus the parameters are not estimated accurately, even if the objective function goes down. good luck, Douglas Eleveld ________________________________ From: [email protected] [[email protected]] on behalf of L.A. ten Berg - Lammers [[email protected]] Sent: Thursday, March 24, 2016 11:10 AM To: '[email protected]' Subject: [NMusers] nonmem question regarding condition number
Dear nmusers, I am currently analyzing PK profiles after a single iv adminstration. Volunteers were sampled frequently: 12 samples per curve. For the structural model 2- and a 3-compartment models are compared. The CWRES vs time plot of the 2-compartment shows the typical wave, indicative for a 3-compartment model. Introduction of a third compartment eliminated the wave, OFV decreased with 180 points, precision of the estimates did change notably, but the condition number increased from 998 to 2.0*E16. Does anyone know how to interpret this large increase in condition number? Best wishes, Laureen ten Berg [Beschrijving: cid:[email protected]] Laureen ten Berg-Lammers Hospital Pharmacist Academisch Medisch Centrum Universiteit van Amsterdam Meibergdreef 9 | 1105 AZ Amsterdam | Room: M01-224 Tel: +31(0)20-5662726 | Pager *62726 | [email protected] ________________________________ AMC Disclaimer : https://www.amc.nl/disclaimer ________________________________ ________________________________ De inhoud van dit bericht is vertrouwelijk en alleen bestemd voor de geadresseerde(n). Anderen dan de geadresseerde(n) mogen geen gebruik maken van dit bericht, het niet openbaar maken of op enige wijze verspreiden of vermenigvuldigen. Het UMCG kan niet aansprakelijk gesteld worden voor een incomplete aankomst of vertraging van dit verzonden bericht. The contents of this message are confidential and only intended for the eyes of the addressee(s). Others than the addressee(s) are not allowed to use this message, to make it public or to distribute or multiply this message in any way. The UMCG cannot be held responsible for incomplete reception or delay of this transferred message.
