All of the other significant differences between the groups were expected from the manner in which they were defined: (1) the OB+ and OB− groups differed significantly in BMI (F1,210 = 315, p < .001); (2) the CP+ and CP− groups differed in the number of conduct disorder symptoms endorsed (F1,210 = 276, p < .001); and (3) the Smoking+ and Smoking− groups differed in the percent reporting other drug (cocaine and opiate) dependence (χ2 = 9.9, p < .002). Importantly, analyses of other characteristics suggested no hidden confounds. The percentage of patients reporting alcohol use during the past week did not differ across groups. In addition, the groups did not differ in the number of MDD symptoms endorsed.
