st: biprobit seemingly unrelated regression w/no constant

["Brown, Derek S. (Contractor)" <dsbrown/Contractor@rti.org>]

I would like to run a bivariate probit (biprobit) in seemingly unrelated
regression form, with no constant (so that I can use effects coding).
The "nocons" option is only available for the regular biprobit, not the
SUR form.

Is there an econometric reason why? If not, can I impose this with a
constraint? (I have another constraint in the model already working, but
my constraint for _cons=0 for each equation seems to be ignored by
Stata.)

Thanks, Derek

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