Characteristics of participants (n (% of sample))
| Time 1 | Time 2 | Time 3 | Time 4 | Time 5 | |
| Grade | |||||
| Seventh | 2187 (49) | 2231 (50) | 2170 (49) | 2268 (48) | 2045 (49) |
| Ninth | 2251 (51) | 2284 (50) | 2255 (50) | 2440 (52) | 2120 (51) |
| Sex | |||||
| Male | 2254 (52) | 2236 (51) | 2187 (51) | 2266 (52) | 2053 (51) |
| Female | 2089 (48) | 2177 (49) | 2081 (49) | 2127 (48) | 1985 (49) |
| Ethnicity | |||||
| White | 3647 (85) | 3619 (82) | 3499 (85) | 3571 (84) | 3287 (86) |
| Hispanic | 298 (7) | 338 (8) | 297 (7) | 345 (8) | 308 (8) |
| Native American | 262 (6) | 280 (6) | 225 (5) | 200 (5) | 143 (4) |
| African-American | 42 (1) | 42 (1) | 45 (1) | 28 (1) | 24 (1) |
| Asian | 42 (1) | 77 (2) | 55 (1) | 65 (2) | 53 (1) |
| Other | 22 (<1) | 30 (<1) | 7 (<1) | 25 (<1) | 14 (<1) |
| Parents | |||||
| Mothers | 989 (76) | 1050 (79) | 1100 (80) | 1136 (81) | 517 (80) |
| Fathers | 309 (24) | 380 (21) | 276 (20) | 274 (19) | 128 (20) |