st: Estimating marginal effect of cross term

["Asif R. Anik" <aranik_2003@yahoo.com>]

Dear Stata users,

I am trying to estimate a 2SLS model in Stata with ivreg2 command. The syntax is 

as follows:

ivreg2 y x1 x2 x3 (x4=x5 x6)

here, x2 is the cross term of x1 and x2. 
 
What should be the syntax to get the predicted value of the dependent variable 
in the first stage regression? In this case, the predicted value of x4.

Now I am interested to calculate the marginal impact of x1 and x4. How to 
estimate the marginal impacts of variables that are part of cross-terms?

Regards

Anik 

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