Table 3 Description of the intervention and control group at baseline in the X:IT study

Background factors

Number of schools (%)

51 (54.3%)

43 (45.7%)

Number of students (%)

2380 (57.2%)

1781 (42.8%)

Average number of students pr. school

49.6

45.0

Sex (boys) (E)

50.8%

51.3%

Ethnic background (A)

• Danes

93.0%

92.8%

• Descendants

4.1%

4.2%

• Immigrants

2.9%

3.1%

Family socioeconomic position (SEP) (C)

• High

33.6%

38.7%

• Medium

48.4%

42.8%

• Low

18.0%

18.5%

Intermediate factors: individual

At least 7 out of 13 right answers on knowledge questions (B)

60.1%

54.2%

Students should be allowed to smoke outdoors on school premises (B)

12.8%

13.8%

Difficult to stay smoke-free if friends smoke (F)

59.9%

60.2%

Willing to comply with parental nonsmoking norms (D)

90.7%

90.0%

Intermediate factors: context

Allowed to smoke at home (A)

4.7%

4.1%

Parents daily smokers (C)

• Male

31.1%

27.9%

• Female

28.7%

24.3%

Best friend smokes (C)

6.9%

8.3%

Teachers control smoking (G)

• Daily

6.4%

6.0%

• Sometimes

27.7%

25.2%

• Don’t know

47.1%

49.3

See teachers smoke (H)

• Daily

17.2%

20.5%

• Sometimes

43.4%

43.1%

Outcome

Have ever tried smoking

17.4%

19.2%

Monthly smokers

3.0%

4.2%