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Re: st: ML estimation, no feasible values-Gauri, 6th July


From   Deepankar Basu <basu.15@osu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: ML estimation, no feasible values-Gauri, 6th July
Date   Thu, 06 Jul 2006 16:37:07 -0400

I think the only think that is missing is another empty bracket for
-theta1- in your -ml model- command. Try the following:

ml model lf mylog (outputpsp=corareapsp labourpsp manurepsp
fertiliserpsp tracpsp oxpsp irripsp) ()

Nothing else needs to be changed.
HTH,
Deepankar

On Thu, 2006-07-06 at 20:18 +0000, Gauri Khanna wrote:
> Dear Statalist,
> 
> I am trying to run an ml maximisation to calculate loglikehood values for my 
> model which has only one equation. It is a loglinear equation. unfortunately 
> I run into problems as no feasible values are found, error message r(491). I 
> even tried the ml search, repeat(10) and also with ml maximize,difficult and 
> also with ml maximize, ltol(1e-4) but I got the same error message r(491) 
> that I have pasted below. I only want to obtain the loglikelihood value 
> estimated, nothing else!
> 
> MY COMMANDS:
> 
> capture program drop mylog
> program mylog
> version 8
> args lnf theta1
> quietly replace `lnf' = ln(norm(`theta1')) if $ML_y1==1
> quietly replace `lnf' = ln(norm(-`theta1')) if $ML_y1==0
> end
> 
> ml model lf mylog (outputpsp=corareapsp labourpsp manurepsp fertiliserpsp
> tracpsp oxpsp irripsp)
> ml check
> ml search
> ml maximize
> 
> 
> OUTPUT GENERATED IN STATA
> 
> . capture program drop mylog
> 
> . program mylog
>   1. version 8
>   2. args lnf theta1
>   3. quietly replace `lnf' = ln(norm(`theta1')) if $ML_y1==1
>   4. quietly replace `lnf' = ln(norm(-`theta1')) if $ML_y1==0
>   5. end
> 
> .
> . ml model lf mylog (outputpsp=corareapsp labourpsp manurepsp fertiliserpsp
> tracpsp oxpsp
> >  irripsp)
> 
> . ml check
> 
> Test 1:  Calling mylog to check if it computes log likelihood and
>          does not alter coefficient vector...
>          Passed.
> 
> Test 2:  Calling mylog again to check if the same log likelihood value
>          is returned...
>          Passed.
> 
> ------------------------------------------------------------------------------
> The initial values are not feasible.  This may be because the initial values
> have been chosen poorly or because there is an error in mylog and it
> always returns missing no matter what the parameter values.
> 
> Stata is going to use ml search to find a feasible set of initial values.
> If mylog is broken, this will not work and you will have to press Break
> to make ml search stop.
> 
> Searching...
> initial:       log likelihood =     -<inf>  (could not be evaluated)
> searching for feasible values
> ...........................................................
> >
> ......................................................................
> >
> .......................................................................................
> >
> .......................................................................................
> >...........................................................................
> 
> could not find feasible values
> r(491);
> 
> 
> Please HELP, what can I do with my model "mylog" to make it find feasible 
> values?
> 
> Thanking you in advance.
> 
> Gauri
> 
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