Table 2.
Baseline and 6-month central tendency measures, Wilcoxon tests, and effect size for self-report data
| Variable | Mean BL (SD) | Mean 6 Mo (SD) | Median BL | Median 6 Mo | Wilcoxon test | p | Effect sizea,b |
|---|---|---|---|---|---|---|---|
| TLFB Days Used Any Drugs | 79.77 (19.38) | 5.19 (19.52) | 90 | 0 | − 3.98 | < .001 | 3.84 |
| TLFB Days Alcohol Intoxication | 15.50 (21.56) | 0.29 (0.64) | 6.50 | 0 | − 3.47 | .001 | .71 |
| ASI Alcohol Use Composite | 0.11 (0.12) | 0.01 (0.03) | 0.09 | < 0.01 | − 3.36 | .001 | 0.83 |
| ASI Drug Use Composite | 0.17 (0.08) | 0.02 (0.04) | 0.18 | < 0.01 | − 4.02 | < .001 | 1.87 |
| ASI Legal Composite | 0.52 (0.14) | 0.40 (0.18) | 0.50 | 0.37 | − 3.07 | .002 | 0.86 |
| ASI Employment Composite | 0.07 (0.36) | − 0.01 (0.42) | 0.05 | − 0.17 | 0.22 | .826 | 0.22 |
| DCS Work | 9.04 (1.56) | 10.90 (1.79) | 9.00 | 11.00 | 157.00 | .002 | 1.19 |
Effect size is the standardized mean difference and is based on sample means rather than medians
aTLFB timeline follow-back, ASI Addiction Severity Index, DCS Developmental Competence Scales; TLFB, number of days used over 90-day period
bSmall = .30, medium = .50, large = .70