Figure 2

Illustration of the distribution of the F statistic evaluated compared with geneset size using the ANOVA-2 procedure on the initial expression data (left panel), on the standardized data (center) and on standardized and unidirectional data (right, FAERI procedure). The graphs in the upper part are generated from random data and show that the directional reduction step induces dependence on the number of members in the geneset. The graphs in the lower part show results obtained from real data (E-GEOD-7479), and illustrate the impact of the standardization of data relative to each probeset as well as dependence on the number of members following the directional reduction step.