Re: nonmem question regarding condition number
Hi Lauren,
my first guess would be that you do not need as many ETAs as you had before
when using 3 compartments. May you also added TAs on the 3rd compartments'
parameter? Either way, please check for overparametrization as Caroline
indicated, perferably starting with the ETAs.
Kind regards
Sven Mensing
Quoted reply history
2016-03-24 11:10 GMT+01:00 L.A. ten Berg - Lammers <
[email protected]>:
> 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
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> *Laureen ten Berg-Lammers*
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