The influence of different choices of cut-off P-values (P0) used in the refinement phase on the sensitivity (SN), the specificity (SP) and the accuracy (AC) of Design-Island applied to a manually curated data set of 1560 putative horizontally transferred genes of Salmonella typhi CT18 generated by Vernikos et al.  is shown in Fig. 2A. Fig. 2B shows corresponding variations of slopes of the curves for SN, SP and AC for different choices of cut-off P-values (P0).