Table II.
Comparison of Distribution of Age at First Use across Interviews at Ages 12, 15, and 18a
| Interview age | 0–5 | 6–8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | Total | SEb |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Percentage reporting age at first use of alcohol—NHSDA | ||||||||||||||
| 12 | 1.5 | 2.5 | 2.7 | 6.8 | 5.4 | 4.1 | 23.1 | 1.2 | ||||||
| 15 | 0.5 | 1.6 | 2.1 | 4.2 | 2.5 | 9.4 | 16.8 | 14.1 | 8.8 | 60.1 | 1.0 | |||
| 18 | 0.8 | 0.8 | 0.8 | 2.1 | 2.0 | 4.5 | 10.1 | 12.7 | 13.0 | 18.2 | 10.2 | 3.3 | 78.7 | 0.7 |
| Percentage reporting age at first use of alcohol—Rutgers Project | ||||||||||||||
| 12-Y | 6.5 | 15.4 | 6.9 | 8.1 | 4.3 | 0.9 | 42.1 | 1.4 | ||||||
| 15-Y | 6.7 | 12.3 | 5.1 | 12.1 | 6.0 | 9.4 | 9.6 | 3.8 | 1.8 | 66.9 | 1.4 | |||
| 15-O | 9.9 | 17.3 | 5.1 | 16.6 | 5.5 | 12.0 | 12.2 | 4.6 | 0.8 | 84.0 | 1.4 | |||
| 18-O | 4.0 | 16.2 | 2.9 | 13.3 | 3.6 | 12.2 | 10.5 | 10.5 | 8.4 | 4.8 | 1.7 | 0.4 | 88.6 | 1.4 |
| Percentage reporting age at first use of tobacco—NHSDA | ||||||||||||||
| 12 | 1.5 | 4.7 | 4.8 | 4.8 | 7.3 | 2.7 | 25.6 | 1.2 | ||||||
| 15 | 1.3 | 5.8 | 1.4 | 4.4 | 5.4 | 9.0 | 7.3 | 10.2 | 1.8 | 46.6 | 1.0 | |||
| 18 | 1.2 | 4.3 | 2.4 | 5.5 | 3.9 | 7.5 | 8.4 | 7.9 | 7.7 | 7.5 | 5.0 | 1.1 | 62.4 | 0.7 |
| Percentage reporting age at first use of tobacco—Rutgers Project | ||||||||||||||
| 12-Y | 2.5 | 2.7 | 4.3 | 3.6 | 0.7 | 13.6 | 1.4 | |||||||
| 15-Y | 0.2 | 4.5 | 1.8 | 3.1 | 4.0 | 10.1 | 10.1 | 6.0 | 1.6 | 41.4 | 1.4 | |||
| 15-O | 5.5 | 4.8 | 9.5 | 7.4 | 12.0 | 11.6 | 5.9 | 1.1 | 57.7 | 1.4 | ||||
| 18-O | 4.0 | 2.3 | 5.5 | 4.4 | 8.2 | 9.1 | 6.9 | 5.5 | 5.3 | 2.3 | 1.1 | 54.7 | 1.4 | |
| Percentage reporting age at first use of marijuana—NHSDA | ||||||||||||||
| 12 | 0.1 | 0.5 | 2.0 | 0.2 | 2.7 | 1.2 | ||||||||
| 15 | 0.4 | 0.6 | 0.2 | 0.8 | 1.4 | 2.9 | 5.7 | 7.4 | 4.9 | 24.4 | 1.0 | |||
| 18 | 0.4 | 1.0 | 0.9 | 0.7 | 1.8 | 5.2 | 4.7 | 7.1 | 6.7 | 6.6 | 2.6 | 37.7 | 0.7 | |
| Percentage reporting age at first use of marijuana—Rutgers Project | ||||||||||||||
| 12-Y | 0.2 | 0.7 | 0.9 | 0.9 | 2.7 | 1.4 | ||||||||
| 15-Y | 0.2 | 1.1 | 0.7 | 1.6 | 3.1 | 9.4 | 9.2 | 2.5 | 27.7 | 1.4 | ||||
| 15-O | 0.4 | 0.2 | 1.1 | 3.6 | 7.4 | 15.2 | 15.2 | 3.4 | 46.3 | 1.4 | ||||
| 18-O | 0.2 | 0.4 | 0.6 | 1.1 | 0.8 | 7.6 | 8.4 | 11.6 | 12.4 | 10.9 | 4.8 | 1.1 | 60.0 | 1.4 |
| Percentage reporting age at first use of hard drugs—NHSDA | ||||||||||||||
| 12 | 0.1 | 0.2 | 1.2 | |||||||||||
| 15 | 0.2 | 0.2 | 2.0 | 2.8 | 5.3 | 1.0 | ||||||||
| 18 | 0.1 | 0.8 | 0.7 | 1.3 | 2.2 | 2.3 | 1.0 | 8.4 | 0.7 | |||||
| Percentage reporting age at first use of hard drugs—Rutgers Project | ||||||||||||||
| 12-Y | 1.4 | |||||||||||||
| 15-Y | 0.2 | 0.4 | 0.9 | 0.9 | 2.5 | 1.4 | ||||||||
| 15-O | 0.2 | 0.2 | 0.4 | 1.3 | 0.8 | 2.9 | 1.4 | |||||||
| 18-O | 0.2 | 0.4 | 1.9 | 5.1 | 10.7 | 1.7 | 20.0 | 1.4 | ||||||
a
Y indicates the younger cohort, O indicates the older cohort in the Rutgers Project.
b
Standard error for a typical prevalence rate P = 10%.