Figure 3From: Ranking genes with respect to differential expressionA subset of the data from Golub et al consisting of the first four samples from each group, was used to assess the performance of the t-test, SAM, samroc and the Bayesian method. The upper panel shows the ordered observed d-statistics versus the expected ordered statistics calculated from the simulation. Looking at the graph it appears that rather a lot of genes are changed. The lower panel shows the estimated FDR as a function of the cut-off δ, such that genes with |d-d expected | >δ will be called differentially expressed. Choosing a cut-off of 0.7, i.e. calling genes that fulfill |d-d expected | > 0.7 differentially expressed will only give about 3% false positives. The proportion of unchanged genes is estimated at 84%, and S0 in (1) is put to the 5% fractile of the SE's. The graph was produced by the samfdr function in SAG.Back to article page