Comparison of the PSSM, ULPB, NPV and ODV methods on the RegulonDB data set. (a) Plot of AUC values across the 26 prokaryotic TFs for each method. (b) Matrix of p -values from pair-wise comparisons. A red solid circle in row i and column j indicates that method i outperformed method j , while a blue one in row i and column j indicates that method i is inferior to method j . The size and darkness of a circle imply the significance of the relationship between two methods. The larger and darker a circle, the more significant the relationship. White background indicates exceeding the usual 0.05 significance cut-off, while gray background indicates the opposite.