Table 1

Characteristics of students participating in each survey in unweighted and weighted data sets

	Survey year	Overall		Survey year	Overall
	2011 %	2013 %	2014 %	2017 %	P value
Total n (unweighted)	(4413)	(4423)	(4576)	(4266)
Unweighted data
Sex (% male)	48	53	48	44	<0.001
Age (years)
12–15	61	68	66	66	<0.001
16–17	39	32	34	34
School attended
Government	62	66	65	62	<0.001
Catholic	20	16	17	15
Independent	18	18	18	24
Socioeconomic status
Lowest 40%	40	42	36	39	<0.001
41%–80%	38	38	38	36
Highest 20%	22	20	26	24
Smoking in social environment
At least one parent smokes	33	32	29	27	<0.001
No friends smoke	66	72	69	72	<0.001
Saw cigarette packs in previous 6 months	64	68	58	56	<0.001
Yes %	64	68	58	56	<0.001
Weighted data
Sex: % male	51	51	51	50	0.99
Age (years)
12–15	69	69	68	69	0.99
16–17	31	31	32	31
School attended
Government	58	57	57	58	1.00
Catholic	23	24	24	22
Independent	18	19	19	20
Socioeconomic status
Lowest 40%	40	41	37	38	0.96
41%–80%	38	41	38	40
Highest 20%	22	19	25	22
Smoking in social environment
At least one parent smokes	33	31	27	27	0.040
No friends smoke	69	74	72	74	0.267
Saw cigarette packs in previous 6 months
Yes %	63	67	56	56	<0.001