Third, we reduced the sample size for trait 2 (Figure 3c, Supplementary Table 3e-g). LCV had high power, while other methods had low power. The effect of trait 2 sample size on MR power was more modest than the effect of trait 1 sample size, suggesting that the number of genome-wide significant SNPs (ascertained using trait 1) is the primary limiting factor for MR power.
