Table 1.
Sample characteristics, by marijuana trajectory group membership (N=932)a
| Total (N=932) |
Non-Use (n=568) |
Low-Stable (n=121) |
Early-Decline (n=65) |
College-Peak (n=78) |
Late-Increase (n=52) |
Chronic (n=48) |
|
|---|---|---|---|---|---|---|---|
|
|
|||||||
| Demographic and Control Variables | |||||||
| % male | 48.5% | 41.9% | 48.1% | 58.0% | 62.0% | 68.9% | 67.9% |
| % White | 73.1% | 68.9% | 75.3% | 85.2% | 80.8% | 77.0% | 83.3% |
| % Hispanic | 4.7% | 4.8% | 6.5% | 4.9% | 3.1% | 4.1% | 2.6% |
| Mean (SD) parents’ neighborhood income during high school |
7.3 (3.4) | 7.1 (3.3) | 7.4 (3.3) | 7.5 (3.4) | 7.5 (3.7) | 7.5 (3.4) | 8.5 (4.1) |
| Mean (SD) typical alcohol quantity (Year 1) |
4.9 (2.7) | 4.3 (2.6) | 5.0 (2.5) | 6.3 (3.4) | 6.1 (2.6) | 5.1 (2.3) | 6.2 (2.6) |
| Year 10 Substance Use | |||||||
| % drank alcohol during past year | 95.6% | 93.7% | 99.2% | 98.5% | 98.7% | 96.2% | 100.0% |
| Mean (SD) days/year alcohol use, among past-year drinkers |
104.3 (81.8) | 91.2 (75.0) | 130.3 (83.0) | 93.9 (70.7) | 131.1 (86.9) | 128.5 (100.4) | 129.3 (101.0) |
| Mean (SD) drinks/day, among past-year drinkers |
2.7 (1.6) | 2.5 (1.6) | 2.8 (1.2) | 2.9 (1.4) | 3.1 (1.6) | 3.0 (1.6) | 3.1 (1.5) |
| % smoked tobacco during past year | 24.8% | 15.3% | 33.9% | 26.2% | 42.3% | 51.9% | 54.2% |
| Mean (SD) days/year tobacco use, among past-year tobacco smokers |
87.1 (124.0) | 81.3 (123.7) | 47.7 (83.5) | 60.6 (100.2) | 89.7 (112.5) | 138.4 (156.9) | 129.4 (147.0) |
| % used marijuana at least once during past year | 34.8% | 17.4% | 61.2% | 38.5% | 50.0% | 86.5% | 87.5% |
| % high-frequency marijuana use (≥200 days/year) |
5.5% | 0.5% | 1.7% | 1.5% | 9.0% | 26.9% | 50.0% |
| Mean (SD) days/year marijuana use, among past-year users |
68.0 (110.1) | 21.4 (52.0) | 27.9 (61.1) | 28.8 (62.2) | 70.9 (98.7) | 122.0 (124.1) | 211.4 (145.6) |
a
Marijuana trajectory group membership is based on the annual observations of past-month marijuana use frequency during Years 1 through 6.