A Probability-Probability plot of the power of PI and PII across 960 scenarios for dichotomous traits simulated under the checkerboard model in the discordant sib pair design. In the main panel, the top-right one, the horizontal and the vertical axes are statistical powers of PII and PI, respectively, and the horizontal and the vertical coordinates of each point are determined by the statistical power of PII and PI of a given scenario. The distributions of the simulation parameters are represented graphically in the vertically tiled panels and the horizontally tiled panels for PI and PII, respectively. The horizontal axes of the vertically tiled panels are the power of PII; the vertical axes of the horizontally tiled panels are the power of PI.