*
* Example from section 6.5, starting on page 147
*
open data beer.dat
data(format=free,org=columns) 1 30 q pb pl pr inc
*
table
*
* Transform variables to logs
*
set logq  = log(q)
set logpb = log(pb)
set logpl = log(pl)
set logpr = log(pr)
set logi  = log(inc)
*
* Create log ratios
*
set logpb_pr = log(pb/pr)
set logpl_pr = log(pl/pr)
set logi_pr  = log(inc/pr)
*
* This is the restricted regression done using the ratios
*
linreg logq
# constant logpb_pr logpl_pr logi_pr
*
* This is the unrestricted regression
*
linreg logq
# constant logpb logpl logpr logi
*
* This does the restricted regression by imposing the adding up constraint.
*
restrict(create) 1
# 2 3 4 5
# 1 1 1 1 0