Figure 1: Power comparison given the same source population for trios and controls (larger proportion of causal variants).

The figure shows the empirical power given the nominal significance level of 0.05. Top row: all causal variants were deleterious; bottom row: 50% of causal variants were deleterious and 50% were protective. The x-axis is the number of population controls, whereas the y-axis is the power. The study subjects (including trio members and population controls) comprised 0:100 (the left column, all were Africans), 20:80 (the second column), 50:50 (the middle column), 80:20 (the fourth column), and 100:0 (the right column, all were Europeans) ratios of Europeans to Africans, respectively.