634) for this purpose. We then permuted the phenotypic and covariate information for these individuals 100,000 times while keeping the genotypic information (LD) unchanged. For each of these permuted datasets, we examined gene-environment interaction effects for parental knowledge and peer deviance. To calculate empirical p-values, we used the equation (R + 1)/(N + 1). R is the number of permutations where the sum of the absolute value of the t-scores for significant SNP interaction effects (p < 0.05) exceeded the sum of the absolute value of the t-scores for significant SNP interaction effects in the observed data. N is the number of permutations (100,000).
