Joint significance of interactions

[anely bekbergenova]

Hello Everybody!

I have a model y = 50+0.3*d-1*d*d+1.5*x+1.5*z-0.5*x*z-3.5*boy+u+5*rnormal() . All of my variables were generated from random variables and havebeen defined already. Boy is a binary variable.
I have been asked to find the joint the joint significance of variables x*z and d^2 interactions. I am not very sure what this means... To prove that they are both not equal to zero?

Thank you all for your input and have a great day.

A.

[Carlo Lazzaro]

Anely:
welcome to this forum.
See -help test-.

[Phil Bromiley]

You will find it easiest to use factor variable notation for your interactions and squares. You also should know that after any estimator like regression, you can issue reg,coefl and Stata will show you how to refer to the specific variable parameters.