Empirical power for GWAS under population stratification.

The number of trios, Ntrio, is assumed to be 1,000. Empirical powers are calculated from 2,000 replicates at the genome-wide significance level 0.05 from Bonferroni method under no population stratification. LIP stands for the proposed method using Liptak method to combine pFBATi and pTi. VAN and ION indicate the VanSteen approach selecting top 20 SNP and Ionita approach using an exponential weighting scheme with partitioning parameters of K = 5 and r = 2 respectively. FBAT indicates the empirical power only from FBATi and EIG indicates the empirical power from EIGENSTRAT.