Cluster analysis of undergraduate drinkers based on alcohol expectancy scores

Expectancies of alcohol's effects have been associated with problem drinking in undergraduates. If subgroups can be classified based on expectancies, this may facilitate identifying those at highest risk for problem drinking. Method: Undergraduates (N = 612) from two state universities completed a web-based survey. Responses to the Comprehensive Effects of Alcohol scale were analyzed using k-means cluster analysis separately within each university sample. Results: Hartigan's heuristic was used to determine that five was the optimal number of clusters in each sample. Clusters were distinguishable based on their overall magnitude of expectancy endorsement and by a tendency to endorse stronger positive than negative expectancies. Subsequent analyses were conducted to compare clusters on alcohol involvement and trait disinhibition. A cluster characterized by endorsement of positive and negative expectancies ("strong expectancy") was associated with a particularly problematic risk profile, specifically concerning difficulties with self-control (i.e., trait disinhibition and impaired control over alcohol use). A cluster with higher positive and lower negative expectancies reported frequent heavy drinking but appeared to be at lower risk than the strong expectancy cluster in a number of respects. Negative expectancy endorsement appeared to represent added risk above and beyond positive expectancies. Conclusions: Results suggest that both the magnitude and combination of expectancies endorsed by subgroups of undergraduate drinkers may relate to their risk level in terms of alcohol involvement and personality traits. These findings may have implications for interventions with young adult drinkers.