Re: [Gretl-devel] Report -- caution! long!
Thanks very much for the recent additions and improvements.
>> Now this is maybe I didn't know how to fully use gretl in
this
>> context. The issue arised on 2 occasions:
>> (1) I had a polynomial regression and I was showing them to enter from
>> the GUI the command something like:
>> prediction = $coeff[1] + $coeff[2]*x + $coeff[3]*x^2
Yes, in gretl that sort of thing is required if you want to
predict for some x-value that's not in the dataset. Or you
could do it by adding one observation to the dataset,
containing the x-values for which you want a prediction, then
asking for an out of sample forecast. I guess we could add a
variant of "fcast" (or maybe a new command-word is wanted),
for use after estimating a model, which takes a vector of
x-values as input and produces the prediction plus a standard
error. That woud be quite simple.
Maybe I am wrong but having to add an observation to the data set to
compute a prediction sounds a bit awkward. I also understand that
these can be easily done with small scripts. On the other hand, if
that is so, implementing a predict command that can encompass a
reasonable number of model types should not be very hard. My 2 Turkish
Kurus (which are less than 1 Euro Cent) is that starting a predict
command (and a button) that will initially work for linear and
polynomial OLS models as well as bivariate logit and probit models
(and maybe 1-2 more most commonly used types). Over time, as needs
arise maybe more can be added.
As Prof. Adkins observes, most people don't appreciate the challenge
of figuring out things or scripts. This is especially true for
professionals who want to get things done fast and as easily as
possible. So one thing that we consider trivial can be a major thing
or a show stopper for those people.
Here is (more or less) the exact converstion that took place:
Talha: OK here we enter these commands to obtain the probabilities for
the 3 cuts. Notice the sum adds up to 100%.
Students: There has to be an easier way to do this.
Talha: You know, gretl is so easy that it is spoiling us.
Students: Stata has it.
Talha: ??? :-P
Cheers
--
“An expert is a person who has made all the mistakes that can be made
in a very narrow field.” - Niels Bohr (1885-1962)
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