include a subset of all relevant alcohol-challenge studies identified in our literature search. We do not believe that this restriction impaired our ability to draw valid conclusions for two reasons. First, we were ultimately able to include 73% of eligible studies. Second, our use of the random-effects model permits us to generalize our findings to studies not included in our analyses (Schmidt, 2010). Nevertheless, both this limitation and the considerable heterogeneity among included studies suggest that conclusions in this research area are not yet definitive.
