Table 1 shows the prevalence rates and correlations between the variables used to construct the DD and PU factor scores. Alcohol and nicotine dependence represented the most common substance dependence diagnoses (∼45% prevalence). Rates for the problem use items were higher and followed the same pattern. Phenotypic tetrachoric correlations among all items were generally high and are shown in Table 1. For example, correlations among the problem use items ranged from 0.47 (between Other Drug and Nicotine problem use) to ∼0.84 (between Other Drug and Cocaine problem use).
