At Mon 12/12/2005 10:30 AM, Richard Williams wrote:
> Also, one thing I find peculiar here is that the equality
> constraint on the constants isn't working, i.e. the constant in
> the first 3 equations is 0 while in the last it is non-zero. I
> would have expected a non-zero and identical value for the
> constant in all 4 equations.
I agree with Richard that this is odd behaviour, I replicated it
with the auto dataset. Also the results are close but not quite
the same as the results from a logistic regression. Oh well, the
main message from this should be that if you want to estimate a
logistic regresion, you should use -logistic- and not -mlogit- with lots of constraints.
*---------example---------------
set more off
sysuse auto, clear
recode rep78 1=2
constraint 1 [2=4]: price foreign _cons
constraint 2 [4=5]: price foreign _cons
mlogit rep78 price foreign, con(1 2)
gen dum = rep78 == 3
logit dum price foreign
*-------end example-------------
Cheers,
Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting adress:
Buitenveldertselaan 3 (Metropolitan), room Z214
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
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