Table 1.

Descriptive statistics and multilevel mixed effects linear regressions for smoking-related knowledge, attitudes, perceived norms and self-efficacy to refuse cigarette offers

	Baseline beginning of grade 5		Follow-up mid of grade 7		Change		Difference in change
	Intervention	Control	Intervention	Control	Intervention	Control
	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Adjusted β*	95% CI	p Value
Knowledge†	30.34 (19.47)	30.11 (19.14)	46.75 (21.59)	37.74 (20.45)	16.53 (26.46)	7.53 (24.13)	9.38	6.73 to 12.04	<0.001
Attitudes/risk perception‡	2.04 (0.51)	2.04 (0.51)	2.24 (0.51)	2.16 (0.54)	0.20 (0.61)	0.12 (0.61)	0.10	0.03 to 0.16	0.002
Norms adult smoking§	6.08 (1.62)	5.97 (1.59)	6.04 (1.62)	6.09 (1.55)	–0.03 (2.09)	0.12 (1.95)	–0.08	–0.24 to 0.07	0.265
Norms peer smoking§	3.08 (2.64)	2.93 (2.56)	4.24 (2.28)	4.02 (2.18)	1.16 (3.10)	1.10 (2.93)	0.15	–0.13 to 0.43	0.283
Self-efficacy to refuse cigarettes¶	2.38 (1.04)	2.36 (1.03)	2.53 (0.80)	2.49 (0.85)	0.15 (1.20)	0.11 (1.22)	0.07	–0.03 to 0.17	0.140

*Adjusted for age, gender, type of school, socioeconomic status, migration background, peer/parent/sibling smoking, sensation seeking, rebelliousness, earlier participation in a prevention programme, baseline value of the respective variable.

†Mean percentage of correct answers in a 7-item quiz.

‡Range 0–3, higher values representing more negative attitude.

§Range 0=nobody smokes to 10=everybody smokes.

¶Range 0–3, higher values representing higher self-efficacy.