RE: 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
Quoted reply history
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From: owner-nmusers_at_globomaxnm.com [owner-nmusers_at_globomaxnm.com] on behalf of Andre Jackson [jacksonan1945_at_gmail.com]
Sent: Thursday, December 10, 2015 9:22 PM
To: 'Leonid Gibiansky'; nmusers_at_globomaxnm.com
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:lgibiansky_at_quantpharm.com]
Sent: Thursday, December 10, 2015 9:59 AM
To: Andre Jackson; nmusers_at_globomaxnm.com
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
>
> Jacksonan1945_at_Gmail.com <mailto:Jacksonan1945_at_Gmail.com>
>