Table 1

Descriptive data for the full sample and subsamples

Cross-sectional sample (total N=2836)Longitudinal sample of baseline never used cigarettes (total n=1726)Longitudinal sample of baseline once/ used to use cigarettes (total n=318)
N/M(%/SD)N/M(%/SD)N/M(%/SD)
Age13.18(0.39)13.18(0.39)13.17(0.39)
SexBoy1411(49.8%)898(48.0%)164(51.6%)
Girl1425(50.2%)898(52.0%)154(48.4%)
Heard of e-cigarettes
(baseline)
No346(12.2%)227(13.2%)24(7.5%)
Yes2383(84.2%)1381(80.0%)286(90.0%)
Don't know103(3.2%)118(6.8%)8(2.5%)
Ever used e-cigarettes
(baseline)
No1867(65.8%)1383(80.1%)70(22.0%)
Yes969(34.2%)343(19.9%)248(78.0%)
Ever used
cigarettes (baseline)
No2196(77.4%)1726)(100.0%0(0.0%)
Yes640(22.6%)0(0.0%)318(100.0%)
Family smokers = none898(31.7%)666(38.6%)42(13.2%)
Family smokers = one852(30.0%)534(30.9%)88(27.7%)
Family smokers = two517(19.2%)298(17.3%)74(23.2%)
Family smokers = three or more569(20.1%)228(13.2%)114(35.8%)
Friend smokers = none1384(48.8%)1050(60.8%)67(21.1%)
Friend smokers = a few1135(40.0%)613(35.5%)189(59.4%)
Friend smokers = most317(11.2%)63(3.7%)62(19.5%)
Intentions4.69(0.77)4.87(0.50)4.48(0.76)
Attitude4.73(0.57)4.88(0.32)4.51(0.65)
Perceived norms4.81(0.57)4.91(0.30)4.66(0.50)
Perceived behavioural control4.61(0.72)4.78(0.49)4.43(0.71)
Self-efficacy4.64(0.77)4.83(0.47)4.41(0.82)
Free school meals*14.24(6.63)13.82(6.55)15.57(6.35)
  • *Mean and SD for this variable based on school-level data.