*
* Example starting on page 18
*
open data food.dat
data(format=free,org=columns) 1 40 food income
*
* PRINT is a quick instruction for showing data. TABLE is a quick instruction for viewing
* statistics on data. It's always useful to do these (TABLE is probably the more useful to
* start) when you first read in data. Make sure that the values make sense.
*
* Both, by the way, are also operations on the View menu. PRINT is the "Data
* Table" operation, and TABLE is the "Statistics" operation.
*
print
table
*
* SCATTER is the instruction for doing x-y graphs. There's another instruction
* (GRAPH) for doing graphs of data against time. The wizard for SCATTER is the
* "Scatter (X-Y) Graph" on the "Data" menu.
*
scatter(style=dots,vlabel="y = weekly food expenditures in $",hlabel="x = weekly income in $",$
 footer="Figure 2.6 Data for the food expenditure example")
# income food
*
* LINREG is the instruction for linear regressions. The dependent variable is on
* the first line, the explanatory variables on the second line starting with the #.
*
linreg food
# constant income
*
* Page 35. The VCV option gives you the covariance matrix of the coefficients. This shows
* the variances and covariances on and below the diagonal and the correlations above. (The
* title "Covariance\Correlation" shows this arrangement)
*
linreg(vcv) food
# constant income