*
* Example 3.5 from pp 82-83
*
open data crime1.raw
data(format=free,org=columns) 1 2725 narr86 nfarr86 nparr86 pcnv avgsen tottime ptime86 qemp86 inc86 $
 durat black hispan born60 pcnvsq pt86sq inc86sq
*
linreg narr86
# constant pcnv ptime86 qemp86
*
linreg narr86
# constant pcnv avgsen ptime86 qemp86