View - ResearchGate

Identifying Differentially Expressed Gene Combinations 183Fig. 4. Comparisons of power for detecting shift patterns as a function of the shiftd between the distributions of the two classes. Methods are identified by differentshades of gray. Correlations used to simulate the bivariate normal are listed at the topof each panel.power of the entropy score, because the highly bimodal marginal distributionwill display lower entropy than each of the components.Generally, the power of entropy score increases with increasing shift effects.However, when the marginal separation becomes very large, the entropy scorecan decrease, as two well-separated subgroups can create a narrow ellipsoid whenpooled. This feature of the entropy score has the advantage that gene combinationswith large univariate separations are less likely to be captured in the topranking sets. Because the gene with significant marginal effect can be found moreeasily by one-gene-at-the-time analyses, one might wish to exclude those whenlooking for gene combinations.