Jmf. Tenberge et al., COMPUTATIONAL SOLUTIONS FOR THE PROBLEM OF NEGATIVE SALIENCES AND NONSYMMETRY IN INDSCAL, Journal of classification, 10(1), 1993, pp. 115-124
Citations number
10
Categorie Soggetti
Social Sciences, Mathematical Methods","Mathematical, Methods, Social Sciences
Carroll and Chang have derived the symmetric CANDECOMP model from the
INDSCAL model, to fit symmetric matrices of approximate scalar product
s in the least squares sense. Typically, the CANDECOMP algorithm is us
ed to estimate the parameters. In the present paper it is shown that n
egative weights may occur with CANDECOMP. This phenomenon can be suppr
essed by updating the weights by the Nonnegative Least Squares Algorit
hm. A potential drawback of the resulting procedure is that it may pro
duce two different versions of the stimulus space matrix. To obviate t
his possibility, a symmetry preserving algorithm is offered, which can
be monitored to produce non-negative weights as well.