*
* Example from pages 842-846
*
cal(q) 1970
open data table21-1.prn
data(format=prn,org=columns) 1970:1 1991:4
*
@bjident(diffs=1,trans=log) gdp
boxjenk(ar=||1,8,12||,diffs=1,constant) gdp
correlate(number=25,qstats,dfc=3,method=yule) %resids