/* Categorical Interaction Exercises */

* Using the National Longitudinal Survey of Women, 1988 sample data
clear
sysuse nlsw88

/* (1) Do living in an SMSA (standard metropolitan statistical area)
       and living in the South have an effect on average hourly wages (wage)?
	   - Run an "additive effects" model (no interaction).  Are both
	   coefficients statistically significant?
	   - Run a model with an interaction effect? Is there an
	   interaction effect?  What does the constant tell us?  What does
	   the smsa coefficient tell us?  What does the south coefficient
	   tell us?  What does the interaction term tell us?
*/
/* (2) Replace SMSA with living in a central city (c_city) in the
       previous problem.
	  - Run an "additive effects" model (no interaction).  Are both
	   coefficients statistically significant?
	   - Run a model with an interaction effect? Is there an
	   interaction effect?   What does the constant tell us?  What does
	   the c_city coefficient tell us?  What does the south coefficient
	   tell us?  What does the interaction term tell us?
*/