For various reasons, more subjects completed the alcohol use assessment than completed the ERP task (e.g., because the assessment was conducted by phone for those unable to schedule an in-person visit). Of the 973 participants with P300 amplitude data, 7 participants did not complete the alcohol use history assessment. To test for possible bias in alcohol use estimates at age 18 introduced by missing ERP data, alcohol use factor scores were compared between those with (n=966, M=0.01, SD=1.01) and without (n=300; M= -0.04, SD=0.96) P300 amplitude data in an independent samples t-test. The results suggest that there was no difference in AAU between those with and without P300 amplitude data at age 18 (t(1264)= -0.72, p =0.48).
