Table 3.

Linear mixed effect model of factor associated with academic performance of different disciplines

Variables	Chinese lesson		Mathematics lessons		English lessons
	β (95%CI)	P	β (95%CI)	P	β (95%CI)	P
Outdoor time, hrs/day	5.770(3.476 ~ 8.064)	< 0.001*	4.051(1.851 ~ 6.252)	< 0.001*	5.737(3.534 ~ 7.940)	< 0.001*
Sleeping time, hrs/day	4.682(2.667 ~ 6.698)	< 0.001*	3.302(1.296 ~ 5.309)	0.001*	5.569(3.682 ~ 7.457)	< 0.001*
Learning time out of school, hrs/day	-1.921(-2.827 ~ -1.015)	< 0.001*	-1.814(-2.710 ~ -0.918)	< 0.001*	-1.041(-1.884 ~ -0.198)	0.016*
Gender, girls/boys	6.101(4.190 ~ 8.013)	< 0.001*	-1.379(-3.284 ~ 0.526)	0.156	4.716(2.923 ~ 6.509)	< 0.001*
Age	2.831(1.245 ~ 4.416)	0.001*	1.816(0.230 ~ 3.402)	0.025*	1.599(0.109 ~ 3.09)	0.036*
Father education
Junior high school and below	—		—		—
High school or vocational school	2.349(-0.620 ~ 5.318)	0.121	1.254(-1.715 ~ 4.224)	0.408	3.153(0.362 ~ 5.944)	0.027*
Undergraduate or junior college	5.040(1.498 ~ 8.582)	0.005*	4.191(0.666 ~ 7.715)	0.020*	6.532(3.216 ~ 9.848)	< 0.001*
Master degree or above	3.391(-3.769 ~ 10.550)	0.353	7.336(0.186 ~ 14.487)	0.044*	9.275(2.551 ~ 15.999)	0.007*
Mother education
Junior high school and below	—		—		—
High school or vocational school	1.726(-1.187 ~ 4.639)	0.245	2.309(-0.599 ~ 5.217)	0.120	0.692(-2.043 ~ 3.426)	0.620
Undergraduate or junior college	4.941(1.551 ~ 8.331)	0.004*	4.021(0.652 ~ 7.389)	0.019*	6.580(3.393 ~ 9.766)	< 0.001*
Master degree or above	10.166(1.108 ~ 19.225)	0.028*	7.337(-1.754 ~ 16.427)	0.114	6.421(-2.134 ~ 14.976)	0.141
Family income (RMB/month)
<  = 6000	—		—		—
6000–10,000	-0.383(-2.927 ~ 2.162)	0.768	-0.002(-2.545 ~ 2.542)	0.999	0.553(-1.838 ~ 2.944)	0.650
10,000–20,000	2.741(-0.081 ~ 5.562)	0.057	0.604(-2.203 ~ 3.412)	0.673	1.194(-1.450 ~ 3.837)	0.376
> 20,000	2.660(-0.944 ~ 6.264)	0.148	1.371(-2.206 ~ 4.947)	0.453	0.061(-3.306 ~ 3.427)	0.972

^*P < 0.05