Table 1. Average daily video screen time for 1 week for left-behind children aged 3 to 6 years.

	Age	N	Screen Time	Number of detections	χ2 value	P value
Overall	3~	107	1.17±0.82	23 (21.49%)	8.32	0.002**
	4~	272	1.39±1.16	85 (31.25%)
	5~	242	1.58±1.03	77 (31.82%)
	6~	196	1.66±1.26	61 (31.12%)
Boys	3~	66	1.22±1.06	14 (21.21%)	4.56	0.043*
	4~	148	1.46±1.13	52(35.14%)
	5~	123	1.61±1.25	42 (34.15%)
	6~	104	1.71±1.33	38 (36.54%)
Girls	3~	41	1.13±0.84	9(21.95%)	6.81	0.011**
	4~	124	1.32±1.07	33 (26.61%)
	5~	119	1.55±1.08	35 (29.41%)
	6~	92	1.62±1.24	23(25%)

Note. figures in () are composition ratios or detection rates %; N: number of subjects

*p<0.05

**p<0.01