*
* Example 6.1 from page 186
*
open data hprice2.raw
data(format=free,org=columns) 1 506 price crime nox rooms dist radial proptax stratio lowstat $
  lprice lnox lproptax
*
linreg price
# constant nox dist rooms stratio
diff(standardize) price / zprice
diff(standardize) nox   / znox
diff(standardize) dist  / zdist
diff(standardize) crime / zcrime
diff(standardize) rooms / zrooms
diff(standardize) stratio / zstratio
linreg zprice
# znox zcrime zrooms zdist zstratio