Figure 1 provides the incremental R2 for polygenic scores at different P-value inclusion thresholds. The variance explained at each P-value threshold in GPS represents the change in R2 from the baseline model (age and sex as covariates) after including the GPS at that P-value threshold. GPS were significantly associated with each alcohol-related behavior across almost all of the P-value thresholds, with the exception of the most restrictive scores in relation to drinking frequency. GPS explained more variance as P-value thresholds became more inclusive, peaking and leveling off at thresholds between P < 0.20 and P < 0.50. We decided to use the most liberal threshold (P < 0.50) for all models going forward.
