The effect of filtering of single genes and metagenes on the results of one-way hierarchical clustering trees (part a), two-way hierarchical cluster heatmaps (part b) and independent component analysis (part c) of the 67 tissues studied. The samples are color-coded according to the classification of tissues introduced in Figure 1. Top-list FC filters select the 3600, 1000 and 100 (from left to right) most strongly differentially expressed genes/metagenes in all samples. Note that the ICA-plots are invariant with respect to reversing the direction(s) of the coordinate axe(s) and thus to mirror and rotational symmetry operations. The right part shows different benchmark criteria for different lengths of the FC-lists ranging from FC-3600 to FC-100 (see top axis). The benchmark criteria were applied to nervous system, immune system and epithelium tissues (see text and Methods section).