[Gretl-users] GUI modification...

[Allin Cottrell]

On Fri, 21 Jul 2006, Talha Yalta wrote:

>> You're making sense, if you mean to request that 
>> transformations of variables could be written into a model 
>> specification. However, I would dispute that this is a "GUI" 
>> feature: it requires typing the model specification.  The 
>> gretl GUI model dialog doesn't require (or allow) any typing 
>> of the model spec.
>
> Yes this is not really a GUI feature but it is indirectly 
> related with the GUI as well. Currently, you run a regression 
> and end up with a lot of newly generated variables, which 
> really don't have to be permanently in the variable list.

I agree, this can be an issue.  It raises a larger design 
question.

When I was first setting up gretl's dialog boxes, I wondered: 
How far do you have to go in making everything "mousable"?  To 
what extent can you just present the user with a text entry into 
which they have to type something?

One of the first relevant examples I looked at was Eviews, and 
there I found lots of instances where there was no 
"mousability", just a text entry.  At first I though, "Great, I 
don't have to spend ages designing a GUI, I'll just do this sort 
of thing."  And the model specification dialog in early versions 
of gretl was based on a simple text entry.

Since then, though, we've developed a long way in terms of 
making things do-able via the mouse.  (The latest substantial 
step was a GUI lag selector in the model dialog, so that users 
don't have to "create" lags first, before invoking them as 
regressors.)

So far as the GUI method is concerned, I think the lag selector 
is about as far as we can go.  Imagine a model dialog where you 
could not only select lags, but for each regressor, select 
whether you wanted level, log, first difference...  The 
complexity becomes totally unmanageable.

Which brings us back to something like the Eviews dialog, with a 
text entry, but a powerful one which enables you to embed 
transformations into the list of regressors.

To some extent (OK, a small extent) we have that in the current 
command-line model specification.  For example:

   ols y 0 x time
   ols y 0 x x(-1)
   ols y 0 x(-1 to -3)
   ols y 0 dummify(z)

where the trend, "time", the lags of x, and the dummy variables 
representing the values of the (discrete) variable z, did not 
pre-exist the command.

It would not be very difficult to generalize this, and allow 
arbitrary transformations of variables to be specified as 
regressors.  But, in the very nature of things, there's no real 
GUI for this sort of functionality.

Is it, then, worth considering a bifurcation of the model 
specification dialog?  A "user-friendly" option (which we have 
already) and an "expert" version (which sticks a vamped-up 
version of the current command-line model specification into a 
text-entry dialog box)?

Allin.