Re: st: NLOGIT

["Rodrigo A. Alfaro" <raalfaroa@gmail.com>]

Check that

(1) Your Stata is updated. -nlogit- was fixed for missing observations.
(2) Your covariates are not all dummies. Manos suggested to get
some multiplicative variables: something like "married (dummy) times
income (in dollars)". Also, if ageskl is age times dummy-skilled and
age times dummy-unskilled why you have both?
(3) Drop the nolog in the process... maybe there is some information
that we/you want to know, such as "not concave", "variable xyz
dropped due to collinearity", etc.
(4) Run a SIMPLE version of the model... I meant really simple.
You should play with fraction of your dataset, and less covariates.

Rodrigo.


----- Original Message ----- 
From: "Neil Shephard" <nshephard@gmail.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, July 24, 2007 8:13 AM
Subject: Re: st: NLOGIT



> MNL == Multiple Nested Logit?
>
> You've given us the command that you use, but not shown what the
> error's Stata is reporting are.  These are likely to be informative in
> helping resolve your problem.
>
> From the FAQ 
> (http://www.stata.com/support/faqs/res/statalist.html#advice)...
>
>    * Say exactly what you typed and exactly what Stata typed (or did)
> in response. N.B. exactly! If you can, reproduce the error with one of
> Stata's provided datasets or a simple concocted dataset that you
> include in your posting.
>
>      Don't send examples like this, which gives no information:
>          o The command -fiddle- worked yesterday, but it is not working 
> today.
>
>    or like this, which gives very little information:
>
>        * I am using -frog-, but I just get the message "invalid syntax".
>
>    This example shows better style, setting aside the fact that its
> answer can be found in the online help:
>
>        * I am using Stata 9 to try to draw a plot using -scatter-.
> Here is an example showing my problem with the auto data:
>
>          . scatter mpg weight, s(p)
>
>        I get lots of very small points. Why doesn't Stata use plus 
> symbols?
>
> Neil
>
> On 7/24/07, Bidisha Sayema <lexshb@nottingham.ac.uk> wrote:
>
> > Dear Statalisters,
> >
> > I have done a MNL of employment status (4 choices: wage employed,
> > unemployed etc) with individual specific controls eg sex, education,
> > age, race etc and in the next stage with only the wage employed run
> > another MNL of occupational choices (3 choices: skilled, unskilled etc)
> > with controls like the first stage (not the same though). But I also
> > want to do a NLOGIT while incorporating all the decisions, so there will
> > be 6 choices in the bottom set (3 choices out of wage employed, 3
> > remaining categories of employment status) along with the first set of 4
> > alternatives. I constructed the data set and the tree is running fine
> > but I was unable to run NLOGIT and was facing error message. Is it due
> > to the use of common individual specific variables in both stages? But I
> > need to have demographic and education variables in both stages. Any
> > suggestion is highly appreciated. A simple version of the model is as
> > follows:
> >
> > nlogit choice (occchoice=ageprof ageskl ageuskl agesemp ageunemp agenemp
> > /*
> > */ age2prof age2skl age2uskl age2semp age2unemp age2nemp)
> > (empstat=ageemp2 ageemp3 ageemp4 /*
> > */ age2emp2 age2emp3 age2emp4 marriedemp2 marriedemp3 marriedemp4),
> > group(caseno) nolog
> >
> > Best Regards
> > Bidisha
> >
> >
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