After confirming that all assumptions for regression analyses were met, a series of multiple regression analyses was conducted to ascertain whether alcohol group status and/or lifetime dosage of alcohol predicted performance on each domain score. For all analyses, the neuropsychological domain score was the outcome variable, and substance use and demographic variables were hierarchically entered as predictors: Either (i) alcohol group status or (ii) lifetime dosage of alcohol were entered on Step 1; lifetime tobacco dose and lifetime dose of all other drugs (including cannabis) were entered on Step 2; and completed years of education, participant age at testing, and language of test administration were entered on Step 3.
