thanks Jack and Sumanta for writing back. I guess the
quick take is that GARCH is not the right model for
the data sets I used. I will try R and see if I get
results.
--- jack <jack(a)deanovell.unian.it> wrote:
On Sun, 25 Dec 2005, sudip mukherjee wrote:
> Hi,
> Everytime I try to run the GARCH model from the
menu
> (model/time series/garch) it gives me an error
message
> "convergence criterion not met". I tried several
> different data series but i get the same message
> everytime. What am i doing wrong. Pl advise.
>
> Sudip
>
Bear in mind that closed form estimators for GARCH
models do not exist, so
estimation must be carried out by means of numerical
maximisation. For
more detail, see chapter 10 of the gretl guide at
http://ricardo.ecn.wfu.edu/pub//gretl/manual/PDF/gretl-guide.pdf
The algorithm we use for assessing convergence in
GARCH models is rather
picky, I am afraid. You might want to have a look at
the discussion that
took place in the list about 1 year ago on a very
near subject:
http://ricardo.ecn.wfu.edu/pipermail/gretl-users/2004-October/000060.html
Other packages sometimes print out "estimates" even
when a form of
convergence we deem acceptable hasn't occurred.
My very personal opinion, however, is that the garch
module needs to
undergo serious revisions, though I also believe
this is not the most
urgent thing in our todo list.
Riccardo `Jack' Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche
jack(a)dea.unian.it
http://www.econ.univpm.it/lucchetti
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