| Characteristics | Boys | Girls | Total | 
      
        | N | % | N | % | N | % | 
      
        | Total | 275 | 49.73 | 278 | 50.27 | 553 | 100.00 | 
      
        | Chronological age (in years) |  |  |  |  |  |  | 
      
        | 15- | 65 | 23.64 | 78 | 28.06 | 143 | 25.86 | 
      
        | 16- | 87 | 31.64 | 90 | 32.37 | 177 | 32.01 | 
      
        | 17- | 85 | 30.91 | 81 | 29.14 | 166 | 30.02 | 
      
        | 18- | 38 | 13.82 | 29 | 10.43 | 67 | 12.12 | 
      
        | Mean(SD) | 16.37 (1.08) | 16.24  (1.15) | 16.31 (1.12) | 
      
        | School Grade |  |  |  |  |  |  | 
      
        | Year One | 146 | 53.09 | 154 | 55.4 | 300 | 54.25 | 
      
        | Year Two | 129 | 46.91 | 124 | 44.6 | 253 | 45.75 | 
      
        | Parents’ marital status |  |  |  |  |  |  | 
      
        | Married | 233 | 84.73 | 225 | 80.94 | 458 | 82.82 | 
      
        | Divorce or others | 42 | 15.27 | 53 | 19.06 | 95 | 17.18 | 
      
        | Father’s education |  |  |  |  |  |  | 
      
        | Primary school or less | 58 | 21.09 | 66 | 23.74 | 124 | 22.42 | 
      
        | Middle school/technical secondary school | 186 | 67.64 | 177 | 63.67 | 363 | 65.64 | 
      
        | Junior college/college and above | 27 | 9.82 | 32 | 11.51 | 59 | 10.67 | 
      
        | Don’t know | 4 | 1.45 | 3 | 1.08 | 7 | 1.27 | 
      
        | Mother’s education |  |  |  |  |  |  | 
      
        | Primary school or less | 84 | 30.55 | 91 | 32.73 | 175 | 31.65 | 
      
        | Middle school/technical secondary school | 167 | 60.73 | 168 | 60.43 | 335 | 60.58 | 
      
        | Junior college/college and above | 21 | 7.64 | 16 | 5.76 | 37 | 6.69 | 
      
        | Don’t know | 3 | 1.09 | 3 | 1.08 | 6 | 1.08 | 
      
        | Family incomea |  |  |  |  |  |  | 
      
        | Below 999 RMB per month | 54 | 19.85 | 58 | 20.86 | 112 | 20.25 | 
      
        | 1000 to 1999 RMB per month | 93 | 34.19 | 108 | 38.85 | 201 | 36.35 | 
      
        | 2000 to 2999 RMB month | 74 | 27.21 | 67 | 24.10 | 141 | 25.50 | 
      
        | Above 3000 RMB month | 51 | 18.75 | 42 | 15.11 | 93 | 16.82 | 
      
        | Intention to smoke** |  |  |  |  |  |  | 
      
        | Very unlikely | 137 | 50.74 | 219 | 81.72 | 356 | 66.17 | 
      
        | Unlikely | 44 | 16.30 | 19 | 7.09 | 63 | 11.71 | 
      
        | Likely | 69 | 25.56 | 25 | 9.33 | 94 | 17.47 | 
      
        | Very likely | 20 | 7.41 | 5 | 1.87 | 25 | 4.65 | 
      
        | No. of Cigarettes smoked per daya ** |  |  |  |  |  |  | 
      
        | 0 cigarette | 141 | 55.29 | 248 | 92.88 | 389 | 74.52 | 
      
        | 1 cigarette | 34 | 13.33 | 12 | 4.49 | 46 | 8.81 | 
      
        | 2 to 5 cigarettes | 63 | 24.71 | 6 | 2.25 | 69 | 13.22 | 
      
        | More than 5 cigarettes | 17 | 6.67 | 1 | 0.37 | 18 | 3.45 | 
    
      Note: