Interaction term in multiple regression with categorical variables


New Member
Hello everybody,

I have question concerning categorical variables and multiple regression:

My Scenario:
I have two independent categorical variables (X1 and X2) coded by dummy variable 0,1, and 2 (i.e. genetic data). If I want to calculate the interaction term, can I also use the product term of X1 and X2? Can somebody explain me the rationale for it? WHy is an interaction term the product of both variables, and in which cases it would be something else... or is it always the product term?

Many thanks in advance for answering my question :)