Table 1.
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 | ||||||
| Urine assay result | 0.78 | 0.41 | 0.64 | 0.48 | 0.63 | 0.48 |
| TLFB (past 30 days) | 0.84 | 0.37 | 0.58 | 0.49 | 0.54 | 0.50 |
| ADAD (past 30 days) | 0.84 | 0.37 | 0.44 | 0.50 | 0.52 | 0.50 |
| Abuse parent DISC | 0.05 | 0.22 | 0.04 | 0.19 | ||
| Abuse youth DISC | 0.14 | 0.34 | 0.03 | 0.18 | ||
| Dependence parent DISC | 0.38 | 0.49 | 0.21 | 0.40 | ||
| Dependence youth DISC | 0.49 | 0.50 | 0.21 | 0.40 | ||
|
Cocaine use | ||||||
| Urine assay result | 0.20 | 0.40 | 0.17 | 0.38 | 0.13 | 0.34 |
| TLFB (past 30 days) | 0.13 | 0.33 | 0.11 | 0.32 | 0.10 | 0.31 |
| ADAD (past 30 days) | 0.18 | 0.38 | 0.10 | 0.30 | 0.08 | 0.27 |
| Abuse parent DISC | 0.04 | 0.20 | 0.07 | 0.25 | ||
| Abuse youth DISC | 0.11 | 0.31 | 0.05 | 0.22 | ||
| Dependence parent DISC | 0.02 | 0.12 | 0.02 | 0.12 | ||
| Dependence youth DISC | 0.01 | 0.10 | 0.01 | 0.07 | ||
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; DISC = Diagnostic Interview Schedule for Children.