El Jueves, 26 de Enero de 2006 23:18, jack escribió:
...The ideal thing to do, in my view, would be to have a separate
command (say, "lagselect") to give you an idea of the order of the VAR you
want to estimate. VECMs wouldn't need a separate procedure, since a VECM
is nothing but a VAR with a peculiar type of restriction on the
parameters.
The most linear way to accomplish this in a script would be something
like:
list VARvars = x y z
n = lagselect(VARvars,BIC)
var n VARvars
having the lagselect command issue some sort of output to let you check
what's happening. Note, by the way, that something like the above can be
achieved by some simple modifications to the script I sent a few days ago.
Now, how would you translate this into a GUI procedure? Maybe you can
select some variables from the main window and then (after right-clicking
or going through the menu) you get the output from lagselect, after which
you decide which lag structure you want and proceed with estimation. Or
would you rather have the option (in the VAR dialog) of automatically
selecting the lag order via AIC or BIC instead of specifying it manually?
Or both things?
If we reach a consensus on
a) whether this is necessary at all
b) if a), if it is urgently needed
c) if a) & b), the "right" way to do it,
then we can get something done.
There is a lag selection procedure in RATS (LAGSELEC.SRC), you can download it
from
http://www.estima.com/procs_alpha.shtml
It works only for univariate series but I suppose this may give us some
indications about doing what you are thinking in gretl.
--
Ignacio Díaz-Emparanza
Dpto. de Economía Aplicada III (Econometría y Estadística)
UPV-EHU