st: Tobit and Regim Switching

[Ahmad Derakhshan <ahmadderakhshan2011@gmail.com>]

Dear StataLister

I have bellow equations:

I*= rXi+ θY1i + φY2i+ ϑ        a measurement equation for Rail and
Road mode choice
Y1i = αX1i + ε1    I* >0         Truck shipment size
Y2i = bX2i + ε2    I*≤0           Rail shipment size

The first equation is a measurement equation about selection of two modes
of transportation (Rail and Road). The second and third are rail
shipment size and
road shipment size. This problem called mode choice and shipment size.
It's like switching regime models.

Here i want to determiine the parameters of equations simultaneously,
but i dont know how to deal with them in tobit regression. cos
presence of Xs variables are not same in 3 equations. And the Tobit
proposed for the model, but the problem here is that: its not same as
ordinary tobit model which have y=1 and 0otherwise, here the
measurement is an equation " I* " ).
How can i use of stata command to takle the model? or you may propose
other methods.

-- 
Best Regards
Ahmad Derakhshan

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