*
* Empirical example from pp 67-70
*
open data cigarett.prn
data(format=prn,org=columns) 1 46 obs lnc lnp lny
linreg lnc
# constant lnp
scatter(footer="Figure 3.9 Residuals vs LNP",hlabel="Log of Real Price(1983$/Pack)",vlabel="Residuals")
# lnp %resids
prj(stderrs=sx) fitted
set upper = fitted+sx*1.96
set lower = fitted-sx*1.96
scatter(footer="Figure 3.10 95% Confidence Band for Fitted Values",hlabel="Log of Real Price(1983$/Pack)",$
  vlabel="Fitted Values") 3
# lnp fitted
# lnp upper
# lnp lower