across studies, and also revealed statistically significant and medium effect size differences within addictive behavior categories, suggesting this was common across addictive drugs (albeit with the exception of marijuana use disorders). In addition, the meta-analysis revealed a significantly larger effect size in studies using clinical samples, suggesting impulsive discounting is more robustly associated with clinically-relevant addictive behavior, not simply participation in these behaviors. In addition to categorical studies, continuous analyses have also reported significant positive associations between level of impulsive discounting and the level of addictive behavior (e.g., Alessi & Petry, 2003; Bobova, Finn, Rickert, & Lucas, 2009; MacKillop et al., 2010; Sweitzer, Donny, Dierker, Flory, & Manuck, 2008). Thus, there is very robust evidence of the association between impulsive delay discounting and addictive behavior in cross-sectional studies.
