Fig 1 shows contour plots for the power per truly associated SNP and R2, for a setting with 50 studies, for a trait with hSNP2=50%, for various combinations of total sample size and CGR. Increasing total sample size enhances both power and R2. When the CGR is perfect, power and R2 (relative to hSNP2) have a near-identical response to sample size. This similarity in response gets distorted when the CGR decreases. For instance, in the scenario of 100k SNPs of which a subset of 1k SNPs is causal with hSNP2=50%, in a sample of 50 studies with a total sample size of 10 million individuals, a CGR of one yields 94% power per causal SNP and an R2 of 49%, which is 98% of the SNP heritability, whereas for a CGR of 0.2 the power is still 87% per SNP, while the R2 of the PGS is 8.5%, which is only 17% of hSNP2. Thus, R2 is far more sensitive to an imperfect CGR than the meta-analytic power is. This finding is also supported by the approximations of power in
