Re: Warning obtained while running SAEM
Dear Tim,
Have you tried to run model 1 (with SQRT) also using $ABBREV PROTECT? The error may occur because of a numeric error that propagates through the SAEM steps.
Jeroen
http://pd-value.com
[email protected]
@PD_value
+31 6 23118438
-- More value out of your data!
Quoted reply history
On 05-03-2024 14:08, T. Preijers wrote:
> Dear NMusers,
>
> While running a simple 1-comp model in NONMEM using SAEM, we discovered a warning resulting from $ERROR. Using a SQRT( **2) describing a mixed error model resulted in zero gradients for the additive error (see Example error model 1 below).
>
> /*Example error model 1*/
>
> $ERROR
>
> IPRED = F
>
> IRES = DV-IPRED
>
> W = SQRT(THETA(1)**2 * IPRED**2 + THETA(2)**2)
>
> IF (W.EQ.0) W = 1
>
> IWRES = IRES/W
>
> Y = IPRED+W*ERR(1)
>
> However, when simplifying the $ERROR code omitting the use of SQRT() and THETA(x)**2 (see Example error model 2 below), a successful SAEM run was obtained.
>
> /*Example error model 2*/
>
> $ERROR
>
> IPRED = F
>
> IRES = DV-IPRED
>
> W = THETA(1) * IPRED + THETA(2)
>
> IF (W.EQ.0) W = 1
>
> IWRES = IRES/W
>
> Y = IPRED + W*ERR(1)
>
> Initial values for both THETAs were positive (TH1: 0.417, TH2: 0.545) and constrained with a lower boundary of 0. Moreover, the expected values for IPRED were ranged from 1-700 mg/L.
>
> Our interest lies in what has driven this error. Perhaps someone else has encountered this before?
>
> Looking forward to receiving any answers/comments!
>
> Kind regards,
>
> *Dr. T. Preijers, PharmD, PhD*
>
> /Hospital Pharmacist and Clinical Pharmacologist/
>
> Hospital Pharmacy Erasmus MC Rotterdam The Netherlands
>
> Rotterdam Clinical Pharmacometrics Group