*
* Examples from section 4.4, pp 140-142
*
open data twoyear.raw
data(format=free,org=columns) 1 6763 female phsrank ba aa black hispanic id exper jc univ lwage stotal $
 smcity medcity submed lgcity sublg vlgcity subvlg ne nc south totcoll
*
linreg lwage
# constant jc univ exper
*
* Using a transformed model to isolate the difference in the coefficients.
*
set totcoll = jc+univ
linreg lwage
# constant jc totcoll exper
*
* This uses the original regression and applies the instruction RESTRICT to test
* the restriction that 1xb2-1xb3=0
*
linreg lwage
# constant jc univ exper
restrict(title="Test of Equality of the Two College Dummies") 1
# 2 3
# 1 -1 0