[Gretl-users] A short (well, maybe not that short) wish list

[Riccardo (Jack) Lucchetti]

On Thu, 31 May 2007, andreas.karlsson at ltv.se wrote:

>
> Dear gretl developers,
>
> Here is a short (well, maybe not that short) wish list of improvements for
> gretl that I hope can be implemented:
>
> 1. For the genr command, add a function for computing the factorial, i.e.
> n!

We have the gamma function for that.

> 2. For Tools > Statistical tables: Add tabs for
> (a) Poisson distribution
> (b) binomial distribution

Yes, that would be useful.

> 3. In Tools > Test statistic calculator: Add
> (a) the possibility for using continuity correction for the one sample
> proportion test by checking a check box
> (b) a new tab for calculating a Z-test for comparing two counts (assuming
> that the counts are large enough for the normal approximation to the
> Poisson to apply)
> (c) a new tab for calculating ANOVA for comparison of K means
>
> 4. In Tools > Nonparametric tests: Add new tabs for calculating
> (a) Friedman’s test (the K sample extension of the sign test)
> (b) Kruskal-Wallis test (the K sample extension of the Wilcoxon rank sum
> test)

It would be very helpful if you could send a script that does these via 
existing gretl commands to me or to Allin or both (or better still, to the 
list). Allin and I are working on substantial additions to the code in 
several areas, and it would help enormously if you could work out an 
algorithm in advance.

> 5. For Tools > Probability distributions: Add
> (a) a tab for the gamma distribution
> (b) the possibility to choose the mean and standard deviation of the normal
> distribution

Agreed.

> 6. In View > Correlation matrix add a check box for also calculating a
> covariance matrix

Agreed.


> 7. For View > Principal components: Add the possibility to plot scree plots
> by checking a check box

Do you mean a graph of the eigenvalues? That would be nice to have too.

> 8. For View > Cross tabulation, please
> (a) add that Fisher's exact test is given as default for 2x2 contingency
> tables
> (b) add to the GUI radio buttons for the options  --row (display row
> percentages) or --column (display column percentages), and a check box for
> the option --zeros (display zero entries)
> (c) add an option to save the contingency table (without the marginal
> totals) as a matrix

Agreed. For (c), we'd have to specify a corresponding "genr" function. 
Would something like

matrix P = table(var1, var2)

be ok?

> 9. For Add > Random variables
> (a) Change the GUI to look like the one in Tools > P-value finder, i.e.
> with tabs for the different distributions and text entry boxes for mean,
> standard deviation, degrees of freedom, etc
> (b) add the gamma distribution

Agreed.

> 10. In File > Export data, add options to export in
> (a) Gnumeric file format
> (b) LaTeX format

(b) could be done, (a) is a bit more tedious. But pardon me, what's wrong 
with CSV?

> 11. Add an option to save a matrix in LaTeX format

See previous point. I should add that Allin and I briefly discussed the 
possibility of adding two matrix commands from reading (writing) matrices 
from (to) CSV files.

> 12. In the data window, there are currently three columns: “ID #”,
> “Variable name” and “Descriptive label”. A new column showing if the
> variable is to be treated as discrete or not would be useful.

I agree totally. But we have plans to change the user interface quite 
substantially, so this item could become part of the new user interface.

> I hope you will consider implementing these features

I hope we'll have time to!

Disclaimer: when I said "Agreed" above, that should read as "Yes, I agree 
that this would be nice to have", not "Yes, I promise that this is going 
in for the next release" :-)


Riccardo (Jack) Lucchetti
Dipartimento di Economia
Università Politecnica delle Marche

r.lucchetti at univpm.it
http://www.econ.univpm.it/lucchetti