Average Adjusted Rand index to compare performances of clustering algorithms: k-means++, Qcut, kNN-Spectral and DBHT for the benchmark data sets collected by de Souto et al[40] (k++ indicates k-means++).

The relatively high performing “Parameter given” results refer to cases when the true number of cluster is given to the algorithm as input. In all the other cases the number of cluster is computed by using internal validity measures. (a) Affymetrix data; (b) cDNA data.