Table 1

Descriptive sample statistics at baseline and attrition analysis

Baseline never-smokers (n=2346) (%)Lost to follow-up (n=1026) (%)Analysed sample (n=1320) (%)p Value
Sociodemographics
 Age at baseline, mean (SD)12.24 (1.01)12.16 (1.09)12.30 (0.93)0.001
 Gender (female)54.951.957.30.008
 SES (below median)51.160.643.8<0.001
 State
  Schleswig-Holstein41.639.843.00.279
  Hamburg28.429.127.8
  Brandenburg30.031.129.2
Personal characteristics
 School performance
  Below average2.53.71.5<0.001
  Average33.737.830.6
  Good49.944.953.9
  Excellent13.913.614.0
 TV screen time
  ≤30 min16.815.517.80.051
  1–2 h59.558.860.1
  3–4 h19.019.818.3
  >4 h4.75.93.8
 Sens. seek. and rebelliousness, mean (SD), range 0–3 0.53 (0.50) 0.56 (0.51) 0.50 (0.49) 0.010
Social environment
 Peer smoking (none)71.771.571.90.858
 Parent smoking (no)53.349.356.40.001
Advertising exposure
 Tobacco advertising, range 0–55
  Low (<1)35.335.335.40.600
  Medium (1–10)38.739.738.0
  High (>10)26.025.026.6
 Non-tobacco advertising, range 0–88
  Low (<35)39.840.839.00.469
  Medium (35–54)32.132.432.0
  High (>54)28.126.829.0
  • Sens. seek., sensation seeking; SES, socioeconomic status.