Table 1 Distributions (%) of the characteristics of the study subjects by gender

Age (yr)

0.370

   13

9.5

6.7

   14

14.1

13.4

   15

17.2

20.7

   16

19.7

21.6

   17

21.1

21.4

   18

18.4

16.3

Material affluence scale (N = 1097)

0.001

Poorest

21.9

16.6

Second poorest

23.4

14.9

Average

20.7

19.4

Affluent

13.7

21.3

Most affluent

15.9

21.3

Missing

5.0

6.5

Family structure (N = 1159)

0.010

Both parents dead

5.2

2.0

Only one parent alive

18.2

16.7

Both parents alive but not living together

22.2

21.2

Nuclear family

54.0

59.5

Missing

0.4

0.6

Father's education (N = 1103)

0.008

Illiterate

9.7

6.5

Primary education

34.6

29.5

Secondary education

28.2

33.5

Tertiary

22.4

24.8

Missing

5.2

5.6

Mother's education (N = 1116)

0.001

Illiterate

18.2

14.6

Primary education

46.6

40.1

Secondary education

22.8

30.4

Tertiary

7.5

11.2

Missing

5.0

3.7

Father's occupation (N = 1022)

0.060

Low grade

65.4

56.7

High grade

25.3

29.3

Missing

9.3

14.0

Mother's occupation (N = 1092)

0.017

Low grade

86.3

80.3

High grade

8.1

12.9

Missing

5.6

6.8

School performance (N = 1158)

<0.001

Low

8.5

16.8

Middle

48.4

54.7

High

42.2

28.1

Missing

0.8

0.5

Plans after graduation (N = 1157)

0.028

Won't continue schooling

14.5

10.1

Continue schooling

84.3

89.9

Missing

1.2

0.3

Mobility 1* (N = 1090)

<0.001

Stable (low)

9.9

5.7

Downward

3.5

3.7

Upward

34.4

25.5

Stable (high)

46.2

58.3

Missing

6.0

6.8

Mobility 2** (N = 1095)

0.005

Stable (low)

7.5

5.4

Downward

6.0

3.9

Upward

36.2

30.6

Stable (high)

43.9

54.2

Missing

6.4

5.9

Tawa use

0.018

Yes

6.8

3.7

No

87.4

91.6

Missing

5.8

4.7

Smoking

0.122

Yes

7.5

4.3

No

85.3

88.5

Missing

7.2

7.1

Paternal smoking

0.195

Ever/current

5.4

7.6

Never

82.4

84.2

Missing

12.2

8.2

Maternal smoking

0.027

Ever/current

3.7

1.7

Never

88.2

93.2

Missing

8.1

5.1