Re: Additive residual error
Hi Siwei,
In a similar situation previously, I've found fixing the additive error to a
small value (~= 0.0001*LOQ) has provided a work-around for this. It usually
arises from a zero measurement needing to be nonzero for estimation purposes.
A better fix is to use the M2 method which should lower the constraint of
needing additive error.
Thanks,
Bill
Quoted reply history
On Feb 11, 2013, at 7:27 PM, "siwei Dai" <[email protected]> wrote:
> Hi, NM users:
>
> I have a typical 2-compartment model that can describe my data quite well,
> except the final gradient for the additive residual error is '0'. I therefore
> fix the additive residual error to '0', but then NM would not run. I tried
> different initial estimations for other parameters but the additive residual
> error seems to be the one that decide whether NM will run. Can anyone tell me
> why this would happen and how to solve it?
>
> Thank you very much in advance for your help.
>
> Siwei