When all variables were examined simultaneously in a single multivariate model (see the last column in Table 3), results indicated that reporting lower levels of HED at baseline, experiencing a serious incident, and being female were the only significant predictors of improved group membership. Other individual and situational factors including reporting greater readiness to change and positive alcohol expectancies, being a first-year student, and reporting other drug use did not uniquely predict improved group membership when statistical adjustment was made to remove confounding influences. These findings indicate that because many individual and situational factors are somewhat related, their unique contributions to intervention outcomes cannot be comprehended fully using univariate analysis alone. For example, greater readiness to change no longer significantly predicted the outcome, in part, because it was related to incident seriousness (r = .32, p < .01) and its effects were confounded with incident seriousness. In contrast, the advantage for female students and for those who experienced a serious incident persisted above and beyond their other co-occurring individual and situational factors and different pre-intervention drinking levels. Note that in all three analyses, we found that having received the BMI did not predict improved group membership.
