Dear All,
I hope this post finds you well. I would like to test for endogeneity by using the command ivprobit. My independent variables are Competition and Competition_square. The dependent variable is Innovation and the instrumental variable Politic. My code is as follow:
Code:
ivprobit Innovation (Competition Competition_square = Politic Politic), twostep asis
Although this code has been successfully executed (with a warning: Politic omitted because of collinearity), I am not sure whether this is the right syntax for the quadratic instrumented variable, and could not find it in the Stata help file.
Could you please help me?
Many thanks for your support!