I don't understand. If isoMDS does not work with distances, why does the help for isoMDS indicate that the "Data are assumed to be dissimilarities or relative distances" ? Equally confusing is the loose use of the terms dissimilarities and distances in the literature. As you point out in your book "Distances are often called disimilarities".
-----Original Message----- From: Prof Brian Ripley [mailto:[EMAIL PROTECTED] Sent: September 8, 2004 11:58 AM To: Hanke, Alex Cc: 'Doran, Harold'; '[EMAIL PROTECTED]' Subject: RE: [R] isoMDS On Wed, 8 Sep 2004, Hanke, Alex wrote: > Distances cannot always be constructed from similarities. This can be done > only if the matrix of similarities is nonnegative definite. With the > nonnegative definite condition, and with the maximum similarity scaled so > that s_ii=1, d_ik=(2*(1-s_ik))^-.5 But isoMDDS works with dissimilarities not distances. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
