[Limdep Nlogit List] Is a multinomial logit model with selection applicable here?

James Giller jgiller at ucdavis.edu
Wed Feb 16 08:20:28 AEDT 2022


Hi,

My dependent variable is based on travel mode choice survey data, and it
has a value for "make no trip at all" as well as values for various modes,
car, transit, taxi, walking, etc. The mode is only observed if the survey
participant would make a trip, which made me consider a sample selection
model.

My dependent variable Y has the following values:
0 = transit
1 = car
2 = carpool
3 = taxi
4 = walking
5 = other
6 = no trip

I created another variable DOTRIP, which is 0 if Y = 6, and 1 otherwise.

I then tried to estimate the following model
PROBIT ; Lhs = DOTRIP ; Rhs = <explanators> ; Hold $
MLOGIT ; Lhs = Y ; Rhs = <explanators> ; Selection ; Pts = 25; Halton $

The above model on the data set as explained returned an error message that
there is insufficient variation in the dependent variable during the MLOGIT
part. I think this is because the value 6 (no trip) is possible for Y, but
none of the observations would be selected in the selection step.

Am I correct in specifying a model with sample selection in this case? Or
should I take a different approach to account for the individuals first
deciding whether or not to travel, then by which mode?

Is there some way to rearrange my data so that the above model will work?

Thank you.
James.


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