* References: Chapters 3, 4 and 7 of
* Jeffrey M. Wooldridge, Introductory Econometrics: A Modern Approach,
* South-Western College Publishing, 2000.
SAMPLE 1 141
READ (GPA1.shd) age soph junior senior senior5 male campus &
  business engineer colGPA hsGPA ACT job19 job20 drive &
  bike walk voluntr PC greek car siblings bgfriend &
  clubs skipped alcohol gradMI fathcoll mothcoll

* Example 3.1, pp. 73-74 and Example 3.4, p. 80.
OLS colGPA hsGPA ACT
* Now consider a simple regression
OLS colGPA ACT   

* Example 4.3, p. 125
OLS colGPA hsGPA ACT skipped
* Find the effect on the colGPA for 5 additional skipped lectures.
TEST 5*skipped

* Example 7.2
* Equation (7.6), p. 216
OLS colGPA PC hsGPA ACT
STOP