*
* Example 20.4 from page 632
*
open data tablef20-2[1].txt
calendar(q) 1950
data(format=prn,org=columns) 1950:1 1983:4 qtr y m1 p
*
set logp = log(p)
graph(footer="Figure 20.6 Quarterly Data on log GDP Deflator")
# logp
set dp = logp-logp{1}
graph(footer="Figure 20.7 First Difference of log GDP Deflator")
# dp
set d2p = dp-dp{1}
graph(footer="Figure 20.8 Second Difference of log GDP Deflator")
# d2p
*
@bjident(diffs=2,method=burg,print) logp