st: nlogit nesting scheme for 3-level degenerate model: data structure

[John Fulton <fulton@ssc.wisc.edu>]

Thanks.  I did not find Heiss's example model L(N) helpful, for reasons 
I won't go into here.

Here's the form of my data with a hypothetical example: a study of 
choices between cake and various kinds of pie.  Please ignore the 
independent variables - they're completely made up and I include them 
only to clarify the syntax.

The nlogittree output would be:
top---->bottom
dessert      type        pie
__________________________________
cake        cake         chocolate
pie         fruit_pie    cherry
                        peach
           cream_pie    banana
                        coconut
the model would be:
nlogit chosen (pie=calories) (type=pie_rating) (dessert=freshness), 
group(person_id)

As you see, the "cake" nest is degenerate.  My model kicks out an error:
"Equation/parameter /cake/ multiply defined"
Is there a "quick fix" for this error?  Or do I need to do some 
restructuring of my data?
Thank you,
John.



Anders Alexandersson wrote:

> To structure the data for a degenerate nest in a 3-level
> non-normalized nlogit model, see pages 12-14 in Heiss' draft online
> article (model L) or pages 250-251 in Heiss' SJ article (model N); The
> syntax for nlogitdn is the same as for nlogit.
> ...
> Anders Alexandersson
> andersalex@gmail.com
>
> John Fulton <fulton@ssc.wisc.edu> wrote:
> > ...Assuming nlogit is appropriate, how should I structure data for a
> > degenerate nest in a 3-level model?
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