Table 2.

Daily usage time of each group with median (P25, P75).

Age groups	Sample size	Daily usage time (minutes)	F a	p b	Post hoc p c
BPS (0–2 y)	607	41.84 (23.27, 75.28)			BPS vs. PS, p = 1.000
					BPS vs. ES, p < 0.001*
PS (3–5 y)	2,370	45.36 (26.99, 73.81)			BPS vs. JHS, p < 0.001*
					BPS vs. SHS, p < 0.001*
ES (6–11 y)	3,370	87.25 (42.89,136.34)	225.72	<0.001	PS vs. ES, p < 0.001*
					PS vs. JHS, p < 0.001*
JHS (12–14 y)	204	60.26 (28.47, 132.03)			PS vs. SHS, p < 0.001*
					ES vs. JHS, p = 0.022*
SHS (15–18 y)	92	53.02 (24.81, 109.48)			ES vs. SHS, p = 0.004*
					JHS vs. SHS, p = 0.354

BPS, before preschool; PS, preschool; ES, elementary school; JHS, junior high school; SHS, senior high school; yrs, years; a, b = Mixed-effects model; c = Bonferroni post hoc tests; ^* = statistically significant.