Table 2. Descriptive statistics of study variables across the three consecutive school days.
| Day 1 | Day 2 | Day 3 | ICCa | |
|---|---|---|---|---|
| Accelerometer wear time (hours)b | 15.51 (15.33, 15.69) |
15.62 (15.44, 15.80) |
15.59 (15.41, 15.77) |
.32 |
| Activity counts (total)c | 154.80 (149.74, 159.87) |
165.67* (160.60, 170.75) |
169.97* (164.89, 175.05) |
.55 |
| During school hours | ||||
| MVPA(during) (mins) | 15.38 (14.07, 16.68) |
15.45 (14.14, 16.76) |
19.01*† (17.69, 20.32) |
.48 |
| SED(during) (mins) | 376.72 (369.78, 383.66) |
356.46* (349.49, 363.43) |
348.53* (341.56, 355.49) |
.58 |
| After school hours | ||||
| MVPA(after) (mins) | 13.07 (11.06, 15.08) |
13.03 (11.02, 15.05) |
13.36 (11.34, 15.38) |
.31 |
| SED(after) (mins) | 251.29 (242.53, 260.05) |
256.57 (247.77, 265.37) |
256.49 (247.68, 265.31) |
.37 |
| SCT (mins)d | 98.76 (88.46, 109.06) |
97.16 (86.86, 107.46) |
97.17 (86.85, 107.50) |
.63 |
| During a night | ||||
| Total sleep time (min) | 396.07 (387.44, 404.70) |
396.11 (387.29, 404.92) |
383.94 (374.75, 393.14) |
.31 |
| Sleep efficiency (%) | 80.74 (79.81, 81.67) |
81.02 (80.06, 81.97) |
80.54 (79.55, 81.52) |
.44 |
| Sleep fragment (%) | 24.69 (23.48, 25.90) |
24.05 (22.81, 25.29) |
24.89 (23.59, 26.18) |
.22 |
| Sleep qualityd | 3.98 (3.89, 4.08) |
4.08 (3.98, 4.18) |
4.10 (4.00, 4.20) |
.60 |
ICC = intra-class correlation; MVPA = moderate- and vigorous-intensity physical activity; SED = sedentary behavior; SCT = screen time.
Note. values are least-square means (95% confidence intervals) estimated from a linear mixed model accounting multiple observation within each individual, unless otherwise specified.
* statistically different from day 1 at the Bonferroni adjusted alpha level of .017.
† statistically different from day 2 at the Bonferroni adjusted alpha level of .017.
a ICCs were calculated using covariance parameters including between- and within-subject variances estimated from a linear mixed model.
b valid accelerometer wear time during waking hours.
c total activity counts accumulated during wear hours were divided by 10,000 to reduce the unit size.
d values are back transformed from log units.