[Gretl-devel] tsls / gmm
Allin Cottrell schrieb:
On Tue, 21 Apr 2009, Sven Schreiber wrote:
> but one unrelated thing I've just noticed: GMM now appears twice, in the
> model menu and in the intrumental variables submenu.
Yes, that's right. The instance under "Instrumental variables"
gives you "automatic" GMM when you specify a model as you would
for TSLS (LIML is also an option for such models). The other GMM
entry gives you a dialog in which you specify a model in full
generality. In scripting terms it's "tsls --gmm" versus "gmm".
hmm, I see, but I've just read the documentation for tsls and my first
impression is that the naming now is a little awkward. For example,
tsls --gmm --two-step
looks funny (read it aloud: two-stage ... two-step). Apart from that,
it's not optimal that when options are provided to tsls it's not tsls
anymore -- quoting from the doc: "the results will differ [from TSLS] in
general"
I haven't thought this through, but what about renaming 'tsls' to
something like 'iv' then and retaining 'tsls' as an alias for 'iv'
(w/o
further options) for a while?
Also I still find it a little confusing to have 'GMM' appear twice in
the menus, I would prefer to have some meaningful qualifier. AFAICS in
the IV submenu it's all about linear specifications, right? So maybe
call it 'linear GMM' or something like that.
these are not definite proposals, just to get the discussion started...
thanks,
sven