Table 1. School Sampling, Response Rates, and Participant Characteristics by Survey Yeara.
| 2008 | 2012 | 2017 | |
|---|---|---|---|
| Schools in Japan | |||
| Junior high | 10 882 | 10 018 | 10 325 |
| Schools sampled | 130 (1.2) | 140 (1.4) | 98 (0.9) |
| Sampled schools that responded | 92 (70.8) | 94 (67.1) | 48 (49.0) |
| Senior high | 5115 | 4603 | 4907 |
| Schools sampled | 110 (2.2) | 124 (2.7) | 86 (1.8) |
| Sampled schools that responded | 80 (72.7) | 85 (68.5) | 55 (64.0) |
| Total student responses | 96 911 | 101 356 | 64 331 |
| Excluded for nonresponse regarding sex or age | 541 | 447 | 2 |
| Excluded for discrepant responses (eg, sex, age, smoking, or drinking) | 690 | 859 | 177 |
| Participant characteristics | 95 680 | 100 050 | 64 152 |
| Sex | |||
| Boys | 48 525 (50.7) | 51 587 (51.6) | 34 582 (53.9) |
| Girls | 47 155 (49.3) | 48 463 (48.4) | 29 570 (46.1) |
| School grade | |||
| Junior high (aged 12-15 y) | |||
| 7 | 13 302 (13.9) | 13 405 (13.4) | 7384 (11.5) |
| 8 | 13 649 (14.3) | 12 884 (12.9) | 7329 (11.4) |
| 9 | 12 925 (13.5) | 12 205 (12.2) | 7415 (11.6) |
| Unknown | 275 (0.3) | 0 | 87 (0.1) |
| Senior high (aged 15-18 y) | |||
| 10 | 20 157 (21.1) | 21 480 (21.5) | 14 201 (22.1) |
| 11 | 18 328 (19.2) | 20 026 (20.0) | 14 212 (22.2) |
| 12 | 16 785 (17.5) | 20 050 (20.0) | 13 404 (20.9) |
| Unknown | 259 (0.3) | 0 | 120 (0.2) |
| Smoking and alcohol use in the past 30 d | |||
| Smoking | 4966 (5.2) | 2851 (2.9) | 1183 (1.8) |
| Alcohol use | 16 110 (16.9) | 12 034 (12.1) | 3584 (5.6) |
a
Unless indicated otherwise, values are presented as the No. (%) of schools or students.