Table 1 Descriptive statistics and collection methods used for the study variables at each wave

Outcome

 Mental well-being

  Psychological distress

32.4

33.1

  Psychiatric distress

6.7

6.9

 Substance use

12.9

25.2

32.0

39.9

 Interaction authority

13.3

12.6

11.8

 Delinquency

29.0

24.3

21.1

 Absenteeism

40.0

46.0

39.6

Personal characteristic

 Sex (female)

50.3

50.1

49.2

49.1

 Ethnicity

  White

87.7

87.7

88.4

88.2

  Indian

5.2

5.2

4.8

5.0

  Mixed

2.9

3.0

2.9

2.9

  Other

4.2

4.1

3.8

3.9

 Religion

  None

37.5

37.7

37.7

37.8

  Christian

52.5

52.4

53.1

52.8

  Muslim

6.2

6.2

5.7

5.9

  Other

3.8

3.8

3.5

3.5

 Parental qualifications

  Degree

18.6

18.5

18.1

18.0

  GCE

33.7

33.5

33.7

33.7

  GCSE

26.3

26.4

26.4

26.4

  Level 1 or below

21.5

21.7

21.8

21.8

 Social class

  High occupation/Professional

41.4

41.9

43.8

41.0

  Intermediate occupation

7.3

7.0

7.2

9.4

  Small occupation/self-employed

13.0

9.1

7.0

11.4

  Supervisory & technical

12.0

13.1

13.2

9.8

  (Semi-) routine occupation

21.2

24.5

25.5

25.9

  Not employed

5.1

4.4

3.3

2.5

 Household income

  Below poverty

27.1

27.3

27.4

27.4

  Middle

41.3

41.4

41.6

41.5

  Highest quartile

31.6

31.4

31.0

31.1

 Housing (renting)

26.8

24.5

24.4

22.5

Extracurricular activity

 Volunteering

8.1

10.8

5.9

16.8

 Religious activities

17.9

15.4

10.2

15.6

 Expressive activities

29.5

25.8

13.7

21.5

 Youth club activities

20.7

17.0

11.4

14.9

 Sports activities

88.6

85.4

93.7

72.1

Family factors

 Parental composition

 Single/no parent

26.2

23.6

24.9

29.0

 Number of siblings

  0

13.5

14.4

16.3

15.9

  1–2

66.3

66.3

65.8

65.7

  3+

20.2

19.2

17.9

18.4

 Parent-adolescent relationship (bad)

6.3

12.6

16.8

11.1

School factors

 Bully victim

  No

62.7

68.7

78.2

67.1

  1 type

19.8

16.5

12.1

15.4

  2 types

9.7

8.9

6.3

10.5

  3 or 4 types

7.8

6

3.4

7.1