Figure 2A-F are receiver-operating characteristic plots showing the dependence of the power of the KWII on proportion of false positives for models 1-GH, 2-GH, 3, 3-GH, 4, 4-GH, 5C, 6C and 7A-7B in Table 1. Models 5A, 5B, 6A, 6B and 7C had power greater than 99% over the range of proportion of false positives examined and are not shown. The open circles in Figure 2A-3 D represent the power for detecting one of the two interacting pairs of loci and the open squares represent the power for detecting both loci. The filled circles in Figures 2C and 2 D correspond to the corresponding model without genetic heterogeneity whereas in Figures 2E and 2F the filled circles are used to distinguish between the different models. The power of the KWII at α-values of 0.001 and 0.0001 are summarized in Table 5 and 6.