Table 2 Homogeneity Test of General Characteristics of the Mothers between the Two Groups at Baseline(N = 51)

Mother’s age

36.28 (4.84)

37.50 (2.97)

-1.08

0.286

Education

< High school

Vocational college

College graduate

Over graduate school

2 (8.0)

9 (36.0)

11 (44.0)

3 (12.0)

2 (7.7)

5 (19.2)

12 (46.2)

7 (26.9)

2.81^*

0.434

Occupation

Homemaker

Full-time job

Part-time job

Unemployed

11 (44.0)

6 (24.0)

5 (20.0)

3 (12.0)

14 (53.9)

6 (23.1)

3 (11.5)

3 (11.5)

0.97^*

0.888

Religion

Yes

No

10 (40.0)

15 (60.0)

13 (50.0)

13 (50.0)

0.52

0.473

Smart device usage time per day, hours (SD)

2.3 (2.2)

2.8 (2.1)

-1.11^†

0.267

Monthly income (10,000 KRW)

< 200

201–400

401<

0

10 (40.0)

15 (60.0)

0

11 (42.3)

15 (57.7)

0.16

0.870

Child’s sex

Girls

Boys

13 (52.0)

12 (48.0)

11 (42.3)

15 (57.7)

0.48

0.488

Age (years)

3

4

5

6

4 (16.0)

7 (28.0)

11 (44.0)

3 (12.0)

2 (7.7)

5 (19.2)

12 (46.2)

7 (26.9)

3.85^*

0.277

Birth order

First

Second

Third<

20 (80.0)

3 (12.0)

2 (8.0)

18 (69.2)

7 (26.9)

1 (3.9)

2.03^*

0.456

Purpose of use (multiple responses, n = 104)

Education

Recreation

Babysitting

Begging

Including all

7 (15.6)

23 (51.1)

7 (15.6)

8 (17.7)

45 (100)

12 (20.3)

26 (44.1)

13 (22.0)

8 (13.6)

59 (100)

Smart device usage time per day, hours (before participation)

2.3 (1.7)

2.7 (1.5)

-1.36^†

0.175