Table 1.
Descriptive statistics for the study variables.
| Combined sample (CS; N = 1,945) | Washington State sample (WASH; n = 961) | Victorian sample (VIC; n = 984) | p value | Difference t / χ2 | Cronbach’s alpha (α) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| M(SD) | 95% CI | M(SD) | 95% CI | M(SD) | 95% CI | CS | WASH | VIC | |||
| Age 25 Problematic substance use | |||||||||||
| AUDIT (%, referent: low risk) Risky use Harmful/high risk use | 19.71 4.04 | – – | 14.21 3.37 | – – | 25.00*** 4.69*** | – – | <.0001 | 33.72 | n/a | n/a | n/a |
| Cannabis (%, referent: low risk) | 12.14 | – | 14.20* | – | 10.14 | – | .011 | 6.52 | n/a | n/a | n/a |
| Grade 7 Demographic characteristics | |||||||||||
| Family socioeconomic status | 1.92 (.49) | [1.91, 1.95] | 1.94 (.49) | [1.91, 1.97] | 1.92 (.49) | [1.89, 1.95] | .344 | .947 | n/a | n/a | n/a |
| Female (%, referent: male) | 50.59 | – | 50.63 | - | 50.56 | – | .975 | .001 | n/a | n/a | n/a |
| Age (years) | 13.01 (.41) | [12.99, 13.02] | 13.09*** (.44) | [12.06, 12.12] | 12.93 (.41) | [12.90, 12.95] | <.0001 | 8.37 | n/a | n/a | n/a |
| Accommodation transitions (%, referent: no transitions) | 25.99 | – | 27.08 | – | 24.92 | – | .279 | 1.17 | n/a | n/a | n/a |
| Grade 7–8 Family environment characteristics | |||||||||||
| Low family conflict | 2.79 (.70) | [2.76, 2.82] | 2.77 (.70) | [2.73, 2.82] | 2.81 (.70) | [2.77, 2.85] | .186 | –1.324 | .68 | .66 | .70 |
| Family management | 3.34 (.47) | [3.31, 3.36] | 3.40*** (.47) | [3.37, 3.43] | 3.28 (.46) | [3.25, 3.31] | <.0001 | 5.44 | .70 | .72 | .69 |
| Opportunities for prosocial involvement | 3.12 (.64) | [3.09, 3.14] | 3.11 (.67) | [3.06, 3.15] | 3.12 (.62) | [3.09, 3.16] | .542 | –.610 | .72 | .74 | .6 9 |
| Parental attitudes favorable toward drug use | 1.35 (.45) | [1.33, 1.37] | 1.22 (.38) | [1.20, 1.24] | 1.47*** (.47) | [1.44, 1.50] | <.0001 | –12.67 | .57 | .50 | .57 |
| Sibling alcohol use (%) | 57.74 | – | 48.94 | – | 66.20*** | – | <.0001 | 55.81 | n/a | n/a | n/a |
| Sibling cannabis use (%) | 19.96 | – | 25.08*** | – | 15.02 | – | <.0001 | 28.97 | n/a | n/a | n/a |
| Grade 9 attachment to parents and substance use | |||||||||||
| Attachment to parents | 2.84 (.72) | [2.81, 2.87] | 2.82 (.73) | [2.77, 2.87] | 2.85 (.71) | [2.81, 2.90] | .350 | –.0935 | .75 | .74 | .76 |
| Past year alcohol use (%) | 58.23 | – | 45.16 | – | 71.35*** | – | <.0001 | 133.72 | n/a | n/a | n/a |
| Past year cannabis use (%) | 16.73 | – | 21.68*** | – | 11.75 | – | <.0001 | 33.59 | n/a | n/a | n/a |
α, Cronbach’s alpha. n/a, scales with one item and therefore a Cronbach’s alpha could not be calculated. %, percent. χ2, chi-square. t, t-statistic. M, mean. SD, standard deviation. Female (coded 0 = male, 1 = female); Victoria (coded 0 = Washington State, 1 = Victoria); Accommodation transitions (coded 0 = no transitions, 1 = transitions); Sibling alcohol use (coded 0 = no use, 1 = recent use); Past year alcohol use (coded 0 = no use, 1 = recent use). Statistically significant state differences for continuous variables calculated using independent t-tests. Statistically significant state differences for dichotomous variables calculated using chi-square tests.