Re: st: nlogit: at least one alternative of variable is contained in muliple alternatives of variable; this is not allowed

[Stefan Bernhard <stefanbernhard88@gmail.com>]

Mike,

this indeed did the job. Thank you so much.

nlogit : "For multi-level models, define the alternative variable at
each level using the alternative variable one level down in the
nesting tree."
 - should be included in the help file and [R]

Best, stefan bernhard,



2013/8/14 Michael Barker <mdb96statalist@gmail.com>:
> Hi Stefan,
>
> I haven't really used nlogit, but I will take a guess at this error message.
>
> It sounds like Stata wants the choice at each nesting level to be
> unique. So the alternative variable for connection should have
> different values for lowend-dsl and highend-dsl. This would create a
> clear nested structure and allow you to eliminate impossible choices,
> like nointernet-highend.
>
> If this is right, you should be able to define the alternative
> variable at each level using the alternative variable one level down
> in the nesting tree. So if your variable creation statements would
> look something like this:
>
> nlogitgen internet = type(yes: lowend | normal | highend , no: no)
> nlogitgen type = connection(lowend: dsl_low | cable_low ,  normal:
> dsl_norm |  ... ,highend: mobile_high | ... ,no: no)
> nlogitgen connection = tariff(dsl_low: ..., cable_low: ..., dsl_norm:
> ... , cable_norm ..., no: 0)
>
> Mike
>
>
> On Wed, Aug 14, 2013 at 4:10 AM, Stefan Bernhard
> <stefanbernhard88@gmail.com> wrote:
>> dear statalisters,
>>
>> -nlogit- seems to be a topic that is not getting much replies from statalist.
>>
>> I can only find one archive entry for this error and that is a dead end.
>>
>> "at least one alternative of connection is contained in muliple
>> alternatives of type;
>> this is not allowed"
>>
>> First, there is a spelling error in there...
>> Second, what is the error trying to tell me and what am I supposed to
>> do to avoid it?
>>
>> I have a 4-level nlogit model, where each case has a choice over 115
>> alternative internet tariffs (one of those being the base "no
>> internet").
>>
>> The choice levels are
>> lev1: internet: 1,0
>> lev2: type: 1,2,3
>> lev3: connection: 1,2,3
>> bottom level: tariff
>>
>> where "type" is an indicator of the target group (low-end, average or
>> high-end user) and "connection" is the mode of connection (dsl, cable,
>> mobile).
>>
>> I set up the data with 3 -nlogitgen- in the form:
>> nlogitgen internet = tariff(yes: 1 | 2 | ... , no: 0)
>> nlogitgen type = tariff(lowend: ... ,normal: ... ,highend: ... ,no: 0)
>> nlogitgen connection = tariff(dsl: ...,cable: ...,mobile: ... ,no: 0)
>>
>> nlogittree tariff connection type internet
>>
>> nlogit choice price bandwidth volume /*
>> */ || internet: , base(no) /*
>> */ || type: age education , base(no) /*
>> */ || connection: household_size , base(no) /*
>> */ || tariff: , case(hh_id)
>>
>>
>> I would really appreciate some clarification on the meaning of this error.
>>
>> best, stefan bernhard,
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