Single class discrimination (SCD) has recently been described for the
analysis of multivariate embedded data. It is a method for determining
informative axes in the data space which promote clustering of the em
bedded, or principal, class about the model origin and dispersal of th
e non-embedded class. Significance testing of the eigenvalues obtained
in a model has been carried out by randomizing the class membership v
ector and recalculating the SCD model 500 times. These random simulati
ons enable the determination of the permutation distribution under the
null hypothesis of no association, and hence can be used to determine
the significance of the first eigenvalue. A method is described to es
timate the permutation distribution of the second and subsequent eigen
values conditional on the fact that the previous eigenvectors in the S
CD model have been accepted as significant.