* Interaction Variables
* Reference: Section 10.1 of
* R. Carter Hill, William E. Griffiths and George G. Judge,
* Undergraduate Econometrics, Second Edition, Wiley.
SAMPLE 1 40
READ (TAB10-1.shd) PIZZA Y AGE
* Equation (R10.1) p. 222
OLS PIZZA AGE Y
* Equation (R10.2) p. 222
GENR YAGE=Y*AGE
OLS PIZZA AGE Y YAGE
* Estimate marginal effects, Equation (R10.3) p. 222
* On the TEST command the variable names represent the coefficients
* Y = $25,000
TEST AGE+25000*YAGE
* Y = $90,000
TEST AGE+90000*YAGE
* Note: the numerical results reported in Equation (R10.3) are
* calculated with some rounding errors.
STOP