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Re: st: biprobit, interactions, and correct marginal effects
From
Richard Williams <[email protected]>
To
[email protected], Statalist <[email protected]>
Subject
Re: st: biprobit, interactions, and correct marginal effects
Date
Sat, 25 May 2013 09:41:57 -0500
You may wish to look at
http://www.stata.com/statalist/archive/2013-01/msg00263.html
http://www.stata.com/statalist/archive/2013-01/msg00293.html
There were several other related posts around
January 6 to January 9 2013. Those posts explain
why Stata does not give you a marginal effect for
an interaction term and suggest some alternatives
that may make more sense anyway.
At 05:39 PM 5/24/2013, Dimitriy V. Masterov wrote:
I would like to calculate the correct marginal effect of an
interaction after a bivariate probit. It is the interaction of the
endogenous binary variable and a continuous exogenous variable.
Here's an example where the outcome is a child attending private
school. I am interested in whether voting for the property tax
increase and the property tax paid make private education more likely:
#delimit;
webuse school;
biprobit
(private = c.years c.logptax##i.vote)
(vote = year c.loginc c.logptax), robust;
I would like to get the AME of just vote#c.logptax. The index function
coefficient for that term is 0.72.
Is there a way to get margins to report this? I don't think this code
margins, dydx(logptax) predict(pmarg1) over(vote) force;
does it because it also included the non-interaction effect of
logptax. Tricking Stata by defining the interaction manually will not
produce the correct AME for reasons described in Ai and Norton (2003).
Any advice would be much appreciated.
Ai, C., and E. Norton. 2003. Interaction terms in logit and probit models.
Economics Letters, 80: 123129
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-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
EMAIL: [email protected]
WWW: http://www.nd.edu/~rwilliam
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* For searches and help try:
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* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/