We used univariate and bivariate LD Score Regression17 to assess the heritability of each phenotype and to estimate a variety of genetic correlations. Analyses included (1) LD Score Regression intercept tests to evaluate the extent to which population stratification or cryptic relatedness may artificially inflate our summary statistics; (2) estimation of genetic correlations across our five phenotypes; (3) estimation of genetic correlations computed within a phenotype but between the larger contributing studies, as an estimate of the extent to which phenotypes were measuring the same genetic risk in different studies; and (4) estimation of genetic correlation between the five phenotypes and a wide variety of other phenotypes related to smoking and alcohol behaviors, and for which GWAS have already been made publicly available.
