Am 13.07.2022 um 16:59 schrieb Sven Schreiber:
Hi again,
I'm wondering what's the status quo about forecast error/confidence
bands in equations with any kind of ARCH effects, say a simple ARCH(1)
or GARCH(1,1). In particular:
- When I estimate the model natively in gretl (Model - Univariate Time
Series - GARCH), I can call up the standard forecast dialog from the
model window (Analysis - Forecast menu), and I get the usual plot with
confidence bands. But I'm not sure whether the confidence bands actually
incorporate the conditional variance from the GARCH part of the model
(from the variance equation). I cannot easily check against a plain OLS
model without GARCH because I also get slightly different coefficients
in the mean equation there. I looked at the built-in help and at the
manual, but it seemed silent on this particular case.
OK, I've looked a little bit at the source, and in lib/src/forecast.c I
find functions like garch_fcast and garch_ldv_sderr, which very much
sound like they do the right thing. Excellent!
Now where should this be mentioned? In the "fcast" section in
doc/commands/gretl_commands_en.xml, or in section 35.3 of the manual,
"The fcast command"? (Or both?)
thanks
sven