SIMPROF tests

All of the clustering methods are able to exploit ‘similarity profile’ (SIMPROF) permutation tests, e.g. for stopping rules for divisive methods or choice of number of groups k in a ‘flat’ clustering. SIMPROF test sequences look for statistically significant evidence of structure in samples which are a priori unstructured (e.g. single samples from each of a number of sites). Under this option, tests are performed at every node of a completed dendrogram, whether constructed agglomeratively or divisively, starting from the top of the dendrogram (all points in a single group) and permitting interpretation of divisions below each node only if a SIMPROF test shows evidence of multivariate structure within that group. Test results are displayed by a colour convention on the dendrograms: samples connected by red lines are not significantly differentiated by SIMPROF, so that only the structure shown by black lines in a dendrogram should be interpreted. The test statistics themselves and their significance levels are given in the Results window indicated by the icon.