Table 1.
2013 Descriptive statistics for the analytical sample by study visit (8th and 9th grades)
| 8th Grade (N=107) | 9th Grade (N=84) | |
|---|---|---|
| Age, mean (SD), years | 13.9 (0.36) | 14.9 (0.36) |
| Female, N (%) | 57 (53.3) | 42 (50.0) |
| Male, N (%) | 50 (46.7) | 42 (50.0) |
| White, N (%) | 74 (69.2) | 65 (77.4) |
| Black, N (%) | 27 (25.2) | 14 (16.7) |
| Other, N (%) | 6 (5.6) | 5 (6.0) |
| Household Inc.: $<40,000, N (%) | 10 (9.5) | 5 (6.0) |
| Household Inc.: $40,000–69,999, N (%) | 16 (15.2) | 10 (11.9) |
| Household Inc.: $70,000–99,999, N (%) | 11 (10.5) | 11 (13.1) |
| Household Inc.: $>99,999, N (%) | 68 (64.8) | 58 (69.1) |
| Parent Educ.: Some College or Less, N (%) | 40 (37.4) | 27 (32.1) |
| Parent Educ.: College Degree, N (%) | 31 (29.0) | 29 (34.5) |
| Parent Educ.: Graduate Degree, N (%) | 36 (33.6) | 28 (33.3) |
| Leave for School, mean (SD), hours from 00:00 | 7.36 (0.41) | 7.01 (0.42) |
| Commute Time, mean (SD), minutes | 17.9 (18.0) | 21.3 (18.3) |
Abbreviations: Educ., education; Inc, income. Missing household income data in 8th grade (N=2).