Figure 3.

Null distributions affected by screening methods. The null distributions are estimated using 500 simulated null data sets. The null distributions shown in the lower panel of Figure 2, serve as the reference distributions (df = 13.76 for d* = 2, df = 29.49 for d* = 3 and df = 64.64 for d* = 4). The screening methods ReliefF, TURF and SURFSTAR are used to reduce the number of SNPs from L = 2000 to d = 20. For the remaining d = 20 SNPs, MDR is used to identify the best d*-way interactions (d* = 2, 3, 4). The resulting null distributions of these models, shown from left to right, do not strictly follow the χ² distribution. The null distributions shift rightwards, compared with those distributions in the lower panel of Figure 2.