*
* Example 9.8 from page 312
*
open data rdchem.raw
data(format=free,org=columns) 1 32 rd sales profits rdintens profmarg salessq lsales lrd
*
* The values of rdintens and profmarg on the data file were truncated to two
* decimal points. In order to reproduce the results in the text, we need to
* recalculate them using the raw inputs.
*
set rdintens = 100.0*rd/sales
set profmarg = 100.0*profits/sales
*
linreg rdintens
# constant sales profmarg
scatter(style=dots,footer="Figure 9.1 Scatterplot of R&D Intensity against Firm Sales")
# sales rdintens
linreg(smpl=sales<30000) rdintens
# constant sales profmarg