Re: MDS distances

[Jean-François Paiement <paiement@xxxxxxxx>]

> I think the Gray/Wessel approach has failed.. it's too hard to figure
> out what the results mean.  (Just trying to be blunt to get your
> attention. ;-)  You start with convenient sounds, measure perception
> and then try to figure out what the MDS dimensions mean.  That hasn't
> worked.  I think that is why people have not been pushing on it very
> hard lately.

One should not try to interpret the "meaning" of MDS dimensions, since
any rotation of an MDS solution is a completely equivalent solution.
Hence, looking at the vectors components of an MDS solution has no
sense unless you find a way to fix some dimensions in a meaningful
way. That's why different MDS algorithms can lead to different (valid)
solutions given the same initial similarity matrix. If your goal is to
find the "intrinsic" dimensions of sound data, my opinion is that it
would be preferable to use state-of-the-art dimensionality reduction
algorithms (Isomap, LLE, non-local techniques, or even PCA), on a set
of points obtained from MDS with no loss in higher dimension.

--
Jean-François Paiement
Research Assistant
IDIAP Research Institute
Martigny, Switzerland
paiement@xxxxxxxx