The correlation between common environmental influences on friends' alcohol use and adolescent own alcohol use was almost one (r = 0.91–0.94). At face value, our results suggest that the common environmental influences on alcohol use overlap almost entirely with those that impact friends' alcohol use. Although rater effects may have contributed to these findings (see below), another study has provided similar results. Walden and colleagues [4] found that the relationship between peer deviance and alcohol use was explained by common environmental factors (although they were not examining peer alcohol use per se).
