Table 5.

Means/Proportions, Standard Deviations, and Sample Sizes for Drug Use Measures Across Assessment Points

	Baseline (n = 190)		6 months (n = 141)		18 months (n = 111)
Substance use measure	M	SD	M	SD	M	SD
Marijuana use African American sample (n = 77)
Urine assay result	0.84	0.37	0.69	0.47	0.69	0.47
TLFB (past 30 days)	0.85	0.36	0.75	0.44	0.75	0.49
ADAD (past 30 days)	0.84	0.37	0.69	0.47	0.67	0.48
Marijuana use Hispanic sample (n = 113)
Urine assay result	0.74	0.44	0.62	0.49	0.60	0.49
TLFB (past 30 days)	0.84	0.37	0.51	0.50	0.48	0.50
ADAD (past 30 days)	0.83	0.37	0.51	0.50	0.44	0.54
Cocaine use African American sample (n = 77)
Urine assay result	0.20	0.40	0.14	0.35	0.14	0.35
TLFB (past 30 days)	0.07	0.25*	0.08	0.27	0.11	0.32
ADAD (past 30 days)	0.12	0.33	0.10	0.30	0.17	0.38
Cocaine use Hispanic sample (n = 113)
Urine assay result	0.18	0.39	0.20	0.39	0.13	0.32
TLFB (past 30 days)	0.17	0.37	0.13	0.34	0.10	0.31
ADAD (past 30 days)	0.20	0.40	0.15	0.36	0.13	0.34

Note. Each measure was scored as 1.00 for use, abuse, or dependence or as 0.00 for no use, no abuse, or no dependence to calculate the above statistics. Thus, cell means are also proportions of use. TLFB = Timeline Followback; ADAD = Adolescent Drug Abuse Diagnosis Scale.

^*p < .017.