st: contrast with probit

[Silke Humbert <shumbert@iew.unizh.ch>]

Dear Stata-community,

I would be happy if someone could help me with the following
problem:

I am using probit with linearly dependent explanatory variables
(i. e. age categories 0-30, 30-50, >50, coded 0,1). If am doing
the regression with all these explanatory variables Stata
naturally drops one if these variables.

The problem now is that I don't want the coefficients of the
regression relative to the variable dropped but rather to the total
average.
And in this way, I would like to have coefficients to all of my
variables (they should sum up to zero then, I think), even though
they are linearly dependent.

Is there a way to set contrasts with probit or any transformation I
can use (if it is a transformation how do I transform a missing
coefficient (dropped category)?)

I am using Stata 8.

Thanks a lot for any comments!
Silke
 
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