RE: nonmem question regarding condition number

Hi Laureen, When a condition number exceeding 1000 is indicative of severe ill conditioning, which means that you model ?is over-parameterized?. Please check these links: http://www.cognigencorp.com/nonmem/nm/99may012003.html http://www.cognigencorp.com/nonmem/current/2008-February/4212.html? Carolina PhD candidate ________________________________ De: [email protected] <[email protected]> en nombre de L.A. ten Berg - Lammers <[email protected]> Enviado: jueves, 24 de marzo de 2016 20:10 Para: '[email protected]' Asunto: [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 ________________________________