st: Mlogit with factor variables

[Saki Tapsell <sakiuchiyama@gmail.com>]

Hi,

I run the multinomial logit model with using y as dependent variable,
and sector and firm_size as independent variables.

"Sector" is a factor variable (1 = food, 2 = tobacco, 3 = textiles, 4
= apparel).

I can do:

mlogit y ib1.sector firm_size

But the tobacco sector has a very small sample, so I don't want to
include that but without dropping that data entirely.  So I do:

mlogit y i1.sector i3.sector i4.sector  firm_size

Which seems to work.  mlogit uses sector == 1   as the base.

But now I want to use the command "prchange" which doesn't like factor
variables.  So I have to convert this to dummy variables.  But if I
do:

mlogit y sector1 sector3 sector4 firm_size

Then it no longer uses sector1 as the base.  and I think treats them
as binary independent variables.  Is there any way to do this
correctly?
So that sector1 is treated as the base, sector2 is not included, but
without using factor variables so that I can use prchange?

Thank you very much

Saki Tapsell
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