Table 1.
Descriptive characteristics of the sample
| Total sample | Males | Females | P valuea | |
|---|---|---|---|---|
| n (%) | n (%) | n (%) | ||
| Total | 10028 (100) | 4333 (51.3) | 5695 (48.8) | |
| Age | ||||
| Mean (SD) | 15.2 (1.8) | 15.2 (1.7) | 15.1 (1.9) | .221 |
| Grade | ||||
| 7 | 1418 (11.7) | 614 (11.0) | 804 (12.4) | .819 |
| 8 | 1702 (12.7) | 801 (13.2) | 901 (12.1) | |
| 9 | 1927 (16.2) | 784 (15.9) | 1143 (16.6) | |
| 10 | 1758 (17.3) | 794 (17.5) | 964 (17.0) | |
| 11 | 1592 (18.2) | 665 (17.6) | 927 (18.8) | |
| 12 | 1631 (24.0) | 675 (24.9) | 956 (23.2) | |
| Ethnic background | ||||
| White | 5813 (56.4) | 2623 (58.7) | 3190 (53.9) | .197 |
| Black | 759 (9.7) | 295 (9.4) | 464 (10.1) | |
| East/South‐East Asian | 951 (8.8) | 376 (8.4) | 575 (9.2) | |
| South Asian | 806 (7.0) | 336 (7.1) | 470 (6.9) | |
| Other | 1699 (18.1) | 703 (16.3) | 996 (19.9) | |
| Subjective socioeconomic status | ||||
| Mean (SD) | 6.9 (1.7) | 7.0 (1.6) | 6.9 (1.8) | .571 |
| Father education level | ||||
| Mean (SD) | 13.0 (3.0) | 13.1 (2.8) | 12.9 (3.3) | .208 |
| Mother education level | ||||
| Mean (SD) | 13.6 (2.9) | 13.5 (2.7) | 13.6 (3.0) | .474 |
| Parental support | ||||
| Mean (SD) | 2.9 (1.2) | 2.8 (1.1) | 3.1 (1.3) | <.001 |
| School subjective social status | ||||
| Mean (SD) | 7.1 (1.9) | 7.2 (1.7) | 7.9 (2.0) | <.001 |
| Frequency of physical activity outdoor | ||||
| 0 d | 2453 (25.3) | 782 (18.2) | 1671 (32.7) | <.001 |
| 1 to 2 ds | 3074 (30.5) | 1177 (29.2) | 1897 (31.9) | |
| 3 to 4 d | 2458 (23.4) | 1148 (25.0) | 1310 (21.6) | |
| All 5 d | 2043 (20.9) | 1226 (27.6) | 817 (13.7) | |
| Meet the physical activity recommendation | ||||
| Do not meet | 7685 (76.7) | 2968 (69.6) | 4717 (84.3) | <.001 |
| Meet | 2343 (23.3) | 1365 (30.4) | 978 (15.7) | |
| Meet the screen time recommendation | ||||
| Do not meet | 6547 (66.6) | 2763 (66.0) | 3784 (67.2) | .323 |
| Meet | 3481 (33.5) | 1570 (34.1) | 1911 (32.8) | |
| Meet the sleep duration recommendation | ||||
| Do not meet | 6652 (66.3) | 2680 (62.5) | 3972 (70.4) | <.001 |
| Meet | 3376 (33.7) | 1653 (37.5) | 1723 (29.7) | |
| BMI categories | ||||
| Normal weight | 7114 (69.3) | 2920 (67.0) | 4194 (71.7) | .056 |
| Overweight/obese | 2914 (30.7) | 1413 (33.0) | 1501 (28.3) |
Note. Data are shown as column %, unless otherwise indicated.
Abbreviations: BMI, body mass index; SD, standard deviation.
P values refer to differences between males and females. A Pearson χ2 test, adjusted for survey design and transformed into F‐statistic, examined sex differences in categorical data compared with an adjusted Wald test for continuous data.