use http://www.stata-press.com/data/r11/dfex
constraint 12 [lf]L.f=1
sspace (f L.f L.lf, state noconstant)
(lf L.f, state noconstant noerror)
(D.ipman f, noconstant)
(D.income f, noconstant)
(D.hours f, noconstant)
(D.unemp f, noconstant),
covstate(identity) constraints(12)
这是时间序列手册(stata11)的原始程序,显示有错,请问是程序盗版问题吗?谢谢