[Limdep Nlogit List] Interaction between ASC and socio-economic variables

[Fredrik Carlsson]

You have an ASC in all utility fcns in the second specification

Best
Fredrik 

Skickat från min iPhone

> 17 juni 2020 kl. 16:51 skrev F WD via Limdep <limdep at mailman.sydney.edu.au>:
> 
> Dear all,
> 
> I am using a mixed logit model to estimate the preferences. In my model,
> there are two types of alternatives and a status quo (alternative specific
> constants). So basically, I had three utility functions. When I tried to
> estimate the basic model without interaction with some socio-economic
> variables, it works. However, When I tried to add the model with
> interaction between ASC and socio-economic variables, it did not work. As
> for your information, I use ASC to measure utility of status quo
> alternative. I use dummy variable coding 1 if the respondent chooses the
> status quo, and 0 otherwise. I want to know the effect of socio-economic
> variable on the probability to opt “status quo”.
> 
> The syntax of mixed logit is below for basic model and it run well
> 
> RPLOGIT   ; Lhs = CHOICE ; Choices = 1,2,3
> 
> ;model:
> 
> U(1,2) = PRICE*PRICE + X76*X76 + HANDLING*HANDLING + X62*X62 + X63*X63      +
> LOCATION*LOCATION + X65*X65  +  QUANTITY*QUANTITY /
> 
> U (3) =  ASC + PRICE*PRICE + X76*X76 + HANDLING*HANDLING + X62*X62 +
> X63*X63 + LOCATION*LOCATION + X65*X65 + QUANTITY*QUANTITY
> 
> ; fcn = ASC(n), Price(c), X76(n), HANDLING(n), X62(n), X63(n), LOCATION(n),
> X65(n), QUANTITY(n)
> 
> ; Maxit = 50 ; Pts = 25 ; Halton ; Output = 3 ; Pds = 3 $
> 
> 
> 
> However, when I run to interact between ASC and some socio-economic
> variables, it does not work.  I got the message: *Error   1027: Models -
> estimated variance matrix of estimates is singular*
> 
> I use the syntax below:
> 
> RPLOGIT   ; Lhs = CHOICE ; Choices = 1,2,3
> 
> ;model:
> 
> U(1,2) = ASC + PRICE*PRICE + X76*X76 + HANDLING*HANDLING + X62*X62 +
> X63*X63 + LOCATION*LOCATION + X65*X65 + QUANTITY*QUANTITY +  AGE*ASCXAGE +
> EDUC*ASCXEDUC + ORGANIC*ASCXORGA + RISKst*ASCXRISK + KTPA*ASCXKTPA +
> COMMUNITY*ASCXKTCO /
> 
> U (3) = ASC + PRICE*PRICE + X76*X76 + HANDLING*HANDLING + X62*X62 + X63*X63
> + LOCATION*LOCATION + X65*X65 + QUANTITY*QUANTITY
> 
> ; fcn = ASC(n), Price(c), X76(n), HANDLING(n), X62(n), X63(n), LOCATION(n),
> X65(n), QUANTITY(n),
> 
> ; Maxit = 50 ; Pts = 25 ; Halton ; Output = 3 ; Pds = 3 $
> 
> 
> 
> Does anyone know why the model in the interaction is not run? Is there any
> wrong in the syntax? Thank you for your help.
> 
> best regards,
> F
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