Figure 2.

Histogram of the z-score Eq. (8) for all individual attributes. The attributes with the highest score are marked. The figure is for the cell cycle dataset of Spellman et al. [24] using the same preprocessing as described in [13] (sec appendix]. After filtering ≈ 2500 GO attributes remained for evaluation. Repeating the analysis for all datasets given in Table 2 yields similar results. The clustering was obtained using a k-means algorithm with Euclidean distance and k = 25, the results do not change significantly for different choices of k (tested between k = 5 - 30, corresponding to the region where the z-score of the mutual information is largest [13]). Note that the top scoring attributes appear to be largely redundant, i.e. a gene that is annotated to the cellular component 'cytosolic ribosome' can be intuitively expected to be also annotated to the biological process 'protein biosynthesis'. See next section for details.