*
* Example 1.3.4 from page 10
*
open data uspop.dat
calendar(years=10) 1790
data(format=free,org=columns) 1790:1 1990:1 uspop
*
* Rescale to millions to keep the numbers more manageable
*
set uspop = uspop*1.e-6
*
* These create the trend and squared trend. T is a reserved variable used in
* SET instructions and elsewhere to represent the current time period.
*
set trend = t
set trend2 = t**2
*
* LINREG does a linear regression. The parameter on the first line is the
* dependent variable. The explanatory variables are shown on a separate line that
* starts with a "#" symbol.
*
linreg uspop
# constant trend trend2
*
* PRJ (in its simplest use) gets the fitted values from the regression just
* completed.
*
prj fitted
*
graph(footer="Figure 1.8 Population of U.S. with Quadratic Trend",vlabel="Millions",$
  overlay=dots,ovsame) 2
# fitted
# uspop