*   R. Carter Hill, William E. Griffiths and Guay C. Lim,  
*   Principles of Econometrics, Third Edition, Wiley, 2008.

* Chapter 7.4  
      
SAMPLE 1 40
READ (pizza.shd) pizza female hs college grad income age

STAT pizza female hs college grad income age

* Equation estimation, page 183.
OLS pizza age income 

* Equation estimation, page 184.
GENR ageinc=age*income
OLS pizza age income ageinc
* Estimate marginal effects, page 184
TEST age+ageinc*25000
TEST age+ageinc*90000
STOP