*
* Examples 9.1 and 9.3, from pages 291 and 305
*
open data table9-1.prn
data(format=prn,org=columns) 1 51
linreg salary
# constant d2 d3
*
* Using separate dummies. We don't have d1 (West) in the dataset so we define it
* as 1-d2-d3, that is, all datapoints which aren't 1 under either of the other
* dummies.
*
set d1 = 1-d2-d3
linreg salary
# d1 d2 d3
*
linreg salary
# constant d2 d3 spending