
Distribution by Membership Status and Performance
(Left panel) The distribution of the absolute value of

by membership status. As in Figure 1 nonmembers' values lie close to 0, whereas the values for participants are distributed similar to the actual phenotype.
(Right panel) The ROC curve, the true positive rate (sensitivity) versus the false positive rate (1-specificity) when we use

to predict membership. A good test should yield a high true positive rate (sensitivity) while keeping the false positive rate low (1-specificity); ideally the AUC should be close to 1. For 300,000 SNPs and a sample size of 1,000, the AUC was 0.83, which is reasonably close to 1.