Re: [OctDev] regress and rcoplot (partially written, please help)

[William P. Y. H. <wil...@gm...>]

On 2/21/06, William Poetra Yoga Hadisoeseno <wil...@gm...> wrote=
:
> On 2/20/06, Paul Kienzle <pki...@us...> wrote:
> >
> > Okay, I added a test of the Longley data set from the NIST Statistical
> > Reference Database.
> >
> > The performance is pretty bad (norm of answer-certified value is about
> > 10^-7), but that's a bit better than the competition.
> >
> > Someone with more R experience than me will have to see if it performs
> > any better.
> >
> > Also, if you can convert bint to standard error values that would be
> > convenient.
> >
> >         - Paul
> >
> > ----
> >
> > % Longley data from the NIST Statistical Reference Dataset
> > Z =3D [  60323    83.0   234289   2356     1590    107608  1947
> >         61122    88.5   259426   2325     1456    108632  1948
> >         60171    88.2   258054   3682     1616    109773  1949
> >         61187    89.5   284599   3351     1650    110929  1950
> >         63221    96.2   328975   2099     3099    112075  1951
> >         63639    98.1   346999   1932     3594    113270  1952
> >         64989    99.0   365385   1870     3547    115094  1953
> >         63761   100.0   363112   3578     3350    116219  1954
> >         66019   101.2   397469   2904     3048    117388  1955
> >         67857   104.6   419180   2822     2857    118734  1956
> >         68169   108.4   442769   2936     2798    120445  1957
> >         66513   110.8   444546   4681     2637    121950  1958
> >         68655   112.6   482704   3813     2552    123366  1959
> >         69564   114.2   502601   3931     2514    125368  1960
> >         69331   115.7   518173   4806     2572    127852  1961
> >         70551   116.9   554894   4007     2827    130081  1962 ];
> > % Results certified by NIST using 100 digit arithmetic
> > % b and standard error in b
> > V =3D [  -3482258.63459582         890420.383607373
> >          15.0618722713733         84.9149257747669
> >         -0.358191792925910E-01    0.334910077722432E-01
> >         -2.02022980381683         0.488399681651699
> >         -1.03322686717359         0.214274163161675
> >         -0.511041056535807E-01    0.226073200069370
> >          1829.15146461355         455.478499142212 ];
> > Rsq =3D 0.995479004577296;
> > F =3D 330.285339234588;
> > y =3D Z(:,1); X =3D [ones(rows(Z),1), Z(:,2:end)];
> > [b, bint, r, rint, stats] =3D regress (y, X, 0.05);
> > assert(b, V(:,1), 6e-7)
> > assert(stats(1), Rsq, 7e-14)
> > assert(stats(2), F, 5e-9)
> >
> >
>
> Yes, you can convert bint to the standard error values with (0.05 is
> alpha, 9 is the degree of freedom):
> ((bint(:, 1) - bint(:, 2)) / 2) / tinv (0.05 / 2, 9)
> but the accuracy will be affected. (It's not so accurate anyway...)
>

I still don't know how to improve the accuracy...
I've added an assertion for the standard error values, but I've got to
set the tolerance to 7.6e-3 (that's not good). Also, I think one
decimal point for the tolerance would be good, what do you think?

By the way, in the octave-forge version (in the repository), the
functions tinv and fcdf are replaced by t_inv and f_cdf. Why?

--
William Poetra Yoga Hadisoeseno