RE: Error in LSODA: Code -5
Eric:
I revisited my data set and indeed I do have MDV=1 values in between values
with a positive DV due to the fact that I am generating data for
compartments where there are no observations. Oftentimes also a measured
concentration within the sampled compartment had the next time point DV
missing so it was set to MDV=1.
Quoted reply history
-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Friday, December 11, 2015 9:40 AM
To: [email protected]; [email protected];
[email protected]
Subject: RE: [NMusers] Error in LSODA: Code -5
Usually tolerance criteria for ODE solvers apply to the solution at the end
of an integration interval. In that case, there is a difference between the
solution at some time instant if it is preceded by an observation record
with MDV=1 or not. So the tolerance settings for ADVAN13 which are ok for
the "normal" subjects could be problematic for the "deficient" subjects if
an integration interval gets too large. So perhaps adding missing
observation records in between could help preventing LSODA errors.
Erik
________________________________________
From: [email protected] [[email protected]] on behalf
of Andre Jackson [[email protected]]
Sent: Thursday, December 10, 2015 9:22 PM
To: 'Leonid Gibiansky'; [email protected]
Subject: RE: [NMusers] Error in LSODA: Code -5
Leonid:
I tried the first suggestion by getting rid of some of the data that was
deficient (i.e., subjects with less than 8 concentrations over the 30 hr.
sampling period) and the LSODA error was not present.
I will also try your other suggestions sequentially to see if they also
improve the analysis.
Thanks for your input.
Andre
-----Original Message-----
From: Leonid Gibiansky [mailto:[email protected]]
Sent: Thursday, December 10, 2015 9:59 AM
To: Andre Jackson; [email protected]
Subject: Re: [NMusers] Error in LSODA: Code -5
Usually this error message is not informative: it just tells you that
something is wrong with the model. It can be fixed by (in the order of
importance)
- cleaning the data (look on concentration-time plots to remove obvious
outliers),
- starting with the better initial parameter values (e.g., your mean
analysis final estimates),
- setting bounds on THETAs,
- removing some ETAs,
- using combined residual error instead of the purely proportional one,
- using residual error with ETAs (instead of Y=IPRED*(1+W*EPS()) use
Y=IPRED(1+W*EXP(ETA())*EPS()),
- other model modifications/simplifications/improvements, including changing
the estimation method (try FO if nothing helps, and then used FO final
estimates to start something more advanced)
Leonid
--------------------------------------
Leonid Gibiansky, Ph.D.
President, QuantPharm LLC
web: www.quantpharm.com
e-mail: LGibiansky at quantpharm.com
tel: (301) 767 5566
On 12/10/2015 8:10 AM, Andre Jackson wrote:
> I have run a control stream that runs okay following MU modeling with
> the mean data to establish the best structural model using NM7 with
> ADVAN 13 TRANS1 TOL=6.
>
> However when I attempt to run the model in a population mode with even
> one eta on a MU I get the following error.
>
> OCCURS DURING SEARCH FOR ETA AT INITIAL VALUE, ETA=0
>
> ERROR IN LSODA: CODE -5
>
> ERROR OCURRED WHILE ATTEMPTING TO OBTAIN INITIAL VALUES FOR ATOL
>
> 0PROGRAM TERMINATED BY OBJ
>
> I have seen some posts in the archives on LSODA and differential
> equations but nothing that seems to address my problem directly.
>
> Does anyone know of any more definitive posts or have suggestions as
> to how best to proceed.
>
> Thanks
>
> Andre Jackson
>
> [email protected] <mailto:[email protected]>
>