Table 1.
Descriptive statistics for the study population.
| Sample size (n (%)) | MVPA (min/day, mean ± SD) | |
|---|---|---|
| Total sample | 81,857 (100) | 48.82 ± 28.71 |
| Sex | ||
| Boy | 40,109 (49.0) | 50.70 ± 29.38 |
| Girl | 41,748 (51.0) | 47.01 ± 27.93**, a |
| Residence locale | ||
| Urban | 41,032 (50.1) | 47.78 ± 28.19 |
| Rural | 40,825 (49.9) | 49.87 ± 29.18**, b |
| School grade | ||
| Primary | 27,351 (33.4) | 50.46 ± 29.42**, c |
| Junior middle | 27,339 (33.4) | 51.44 ± 28.54 |
| Junior high | 27,167 (33.2) | 44.53 ± 27.64**, c |
| Family type | ||
| Both parents | 11,762 (14.4) | 49.39 ± 28.93*,d |
| Both parents and grandparents | 2393 (2.9) | 48.91 ± 28.84*,d |
| Grandparents | 61,639 (75.3) | 48.80 ± 28.66 |
| Single parent and step-parent | 809 (1.0) | 48.36 ± 28.12 |
| Single parent | 4724 (5.8) | 47.95 ± 28.59 |
| Other | 530 (0.6) | 46.44 ± 29.77 |
| Parental education | ||
| Primary school or under | 10,270 (12.6) | 46.13 ± 28.11 |
| Junior middle school | 29,989 (36.6) | 48.21 ± 28.29 |
| Junior high school | 18,849 (23.0) | 49.32 ± 28.74 |
| College | 8581 (10.5) | 50.31 ± 29.50 |
| University bachelor | 11,075 (13.5) | 50.44 ± 29.35 |
| University master or higher | 3093 (3.8) | 50.56 ± 29.02**, e |
| BMI | 81,857 (100) | 19.75 ± 3.50 |
Note: BMI is presented as average BMI percentile ± SD, kg/m2.
Abbreviations: BMI = body mass index; MVPA = moderate-to-vigorous physical activity.
*
p < 0.01.
**
p < 0.001.
a
Compared with boys.
b
Compared with urban children.
c
Compared with junior middle school children.
d
Compared with children living in other arrangements combined.
e
Compared with children whose parents reported lower levels of education.