We performed a joint analysis of our GWAS results on EduYears, Cognitive Performance, Math Ability, and High Math using MTAG11. Supplementary Table 14 shows moderately high pairwise genetic correlations, ranging from 0.51 to 0.85, which motivate the multivariate analysis. The MTAG analyses were restricted to SNPs that passed MTAG-recommended filters in all files with summary statistics. We dropped (i) SNPs with minor allele frequency below 1% or (ii) SNPs with sample sizes below a cutoff (66.6% of the 90th percentile), leaving approximately 7.1 million SNPs found in all four results files. Supplementary Table 41 reports the increases in effective sample size from using MTAG for each set of GWAS results.
