Hi,
When I seasonal adjust a particular time series (the Euro-Area 15 real public investmente expressed in households consumption) stumbled upon
a systematic difference (a shift) between the seasonal adjusted series produced using X11 with the multiplicative option Versus usin the log-additive
option (preceded or not by a boxjenk step).
Questions:
(1) Why the difference? (May be it is related to outliers?)
(2) What method is more reliable?
(3) Shouldn't be exactly equivalent the result from seasonal adjust X with MULTIPLICATIVE and LOGADD and seasonal adjust LOG(X) with ADDITIVE????? What explain the differences?
What method is more reliable (in short samples)?
I have read the User's Guide, Reference Manual and X11 Suplement not founding any light about it.
I attach my example (code and data).
Best Regards,
Rodolfo