st: nested logit model

["Wei Tan" <tanwei@hotmail.com>]

Hi,

I need to estimate a nested logit model including outside alternatives.

In my model, I have four choices, j=2,...5 and an outside alternatives j=1.

I group the four choices to two group S1={3,2} and S2={5,4}

at the upper layer of nest, I have choice 1, S1 and S2.

I used the following command

nlogit chosen (choice=price) /*
		*/ (type2= x), group(newid)  ivc(choicezero=1)

the nest structure shows

type2                  choice
choicezero            1
S1                       2
                         3
S2                       4
                         5

the program shows an error message

choicezero not found
r(198)

I guess that my problem is that I did not specify the model correctly. I 
wonder if someone could help me how to specify the correct model.

wei

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