Scale | Grade 8 (n = 2276) | Grade 9 (n = 2226) | |||
---|---|---|---|---|---|
Boys | Girls | Boys | Girls | ||
N (%) | 1150 (50.5) | 1126 (49.5) | 1128 (50.7) | 1098 (49.3) | |
Household income (1000 Korean won = USD 0.88) (%) | |||||
Q1 (lowest-2,999,999) | – | – | 21.0 | 20.4 | |
Q2 (3,000,000–4,199,999) | – | – | 30.9 | 27.8 | |
Q3 (4,200,000–5,999,999) | – | – | 21.3 | 25.5 | |
Q4 (6,000,000–highest) | – | – | 26.8 | 26.3 | |
Academic performance (M ± SD) | 1–5 | – | – | 2.75 ± 0.82 | 2.76 ± 0.78 |
Height (M ± SD) | 167.58 ± 7.09 | 159.41 ± 5.35* | 171.26 ± 6.31 | 160.42 ± 5.30 * | |
Weight (M ± SD) | 57.88 ± 11.62 | 50.18 ± 7.70* | 61.25 ± 11.24 | 51.59 ± 7.15 * | |
BMI (M ± SD) | 20.53 ± 3.49 | 19.73 ± 2.74* | 20.85 ± 3.39 | 20.02 ± 2.51 * | |
Age (M ± SD) | 12.15 ± 0.60 | 12.10 ± 0.59 | 13.16 ± 0.59 | 13.11 ± 0.63 | |
Pubertal development (M ± SD) | 0–6 | 1.27 ± 1.32 | 2.63 ± 1.12* | – | – |
Depression (M ± SD) | 1–5 | 3.15 ± 0.61 | 3.11 ± 0.61 | 2.99 ± 0.61 | 2.93 ± 0.63 |
Self-esteem (M ± SD) | 1–5 | – | – | 2.84 ± 0.45 | 2.80 ± 0.01* |
Screen time during weekdays (min)a (M ± SD) | |||||
Computer/video games | 86.16 ± 65.88 | 84.35 ± 66.63 | 88.57 ± 67.11 | 69.83 ± 67.29 | |
TV watching | 89.59 ± 66.87 | 96.78 ± 73.13* | 84.06 ± 63.43 | 94.73 ± 75.38* | |
Screen time on weekends (min)a (M ± SD) | |||||
Computer/video games | 162.48 ± 104.59 | 135.15 ± 93.91 | 157.88 ± 102.58 | 114.87 ± 93.35 * | |
TV watching | 153.97 ± 95.95 | 170.37 ± 104.97 | 137.06 ± 89.12 | 168.91 ± 107.17* | |
Screen time total (min)a (M ± SD) | 123.05 ± 55.77 | 121.66 ± 54.48 | 114.62 ± 55.21 | 109.38 ± 60.79 * |