Subject: Re: MDS distances From: beaucham <beaucham@xxxxxxxx> Date: Wed, 21 Jun 2006 13:05:31 -0500I was surprised to receive four new responses to my query of last week, when I received several responses, mostly off the list. I am also getting some local help. One problem is that I haven't been using MatLab directly but rather through an off-campus colleague who is currently unavailable for questions. However, I am now getting some on-campus help, using both MatLab and Systat, as well as a member of this list, using Statistica. Also, I'm boning up on MDS, and I expect to get my hands on MatLab very soon. One thing I found out is that lower dimension MDS coordinates of a high dimension calculation are not the same as the corresponding dimension coordinates for a low dimension calculation. I.e., it doesn't work like orthogonal functions such as Fourier series. Another thing is the triangular inequality (p(A,C)<=p(A,B)+p(B,C)) of the proximity matrix has to be satisified -- our matrix fortunately satisfies that. The upshot is that other people have run jobs on my data that have achieved relatively low stresses with linear and monotonic 2-D and 3-D solutions. I'm not entirely satisfied with the results, but it's getting close. The next step is to discovery aspects of the stimuli (musical tones) which correlate well with the dimensions or combinations of dimensions. For more details on the stimuli, the method of testing, and the provisional MDS results please look at http://ems.music.uiuc.edu/beaucham/mds/mds.txt Jim Beauchamp Univ. of Illinois at Urbana-Champaign jwbeauch@xxxxxxxx