 Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

# Re: st: marginal effects in biprobit and average treatment effect in switching probit

 From Monica Oviedo To statalist@hsphsun2.harvard.edu Subject Re: st: marginal effects in biprobit and average treatment effect in switching probit Date Thu, 14 Jun 2012 03:45:09 -0700 (PDT)

```Dear Statalist:

I'm estimating the effect of an endogenous dichotomous variable y2 on a
dichotomous variable y1 using a recursive biprobit model:

biprobit (y1=x y2) (y2=x z)

Where z is the exclusion restriction. I'm interested in the marginal effect
of y2 on y1, which I think is:

E[y1/y2=1] - E[y1/y2=0]

I did what Austin Nichols suggested in this thread (namely, the conditional
prob of Y1=1 given y2=1 less the conditional probability of Y1=1 given y2=0,
letting y2=1 and y2=0 in turn for each observation, and then averaging over
observations). In addition, I followed the procedures sugested by him in
this file:
http://www.stata.com/meeting/chicago11/materials/chi11_nichols.pdf

This is:

margins, dydx(y2) predict(pmarg1) force

I think the latter is correct for estimating what I need. However, I get
very different results from both procedures (in the first case a marginal
effect of 0.08 vs a marginal effect of 0.45 using the second way).

What is the difference between both procedures? Is it supposed that they
estimate the same effect?

A final question is if biprobit is well suited for estimate the following:

biprobit (y1=x y2 x*y2) (y2=x z)

This is, if  there is any problem when an interaction term between the
endogenous variable y2 and a continous x is added.

Regards,

Monica Oviedo

--
View this message in context: http://statalist.1588530.n2.nabble.com/st-marginal-effects-in-biprobit-and-average-treatment-effect-in-switching-probit-tp4494808p7580200.html
Sent from the Statalist mailing list archive at Nabble.com.
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```