Table 2 Characteristics of the sample by health risk behavior patterns

Gender

 Male

8390 (49.8)

4856 (57.9)^a

1869 (22.3)^b

1240 (14.8)^c

423 (5.0)^a

 Female

8463 (50.2)

4977 (58.8)^a

1204 (14.2)^b

1862 (22.0)^c

420 (5.0)^a

Grade

 Junior school

9235 (54.8)

5187 (56.2)^a

1685 (18.2)^a,b

1793 (19.4)^b

570 (6.2)^c

 Senior school

7618 (45.2)

4646 (61.0)^a

1388 (18.2)^a,b

1311 (17.2)^b

273 (3.6)^c

Residency

 Rural

5805 (34.4)

3441 (59.3)^a

1015 (17.5)^a

1078 (18.6)^a

271 (4.7)^a

 Urban

11,048 (65.6)

6392 (57.9)^a

2058 (18.6)^a

2026 (18.3)^a

572 (5.2)^a

Only child

 Yes

5710 (33.9)

3261 (57.1)^a

1164 (20.4)^b

951 (16.7)^a

334 (5.8)^b

 No

11,143 (66.1)

6572 (59.0)^a

1909 (17.1)^b

2153 (19.3)^a

509 (4.6)^b

Father’s education level

46.25

 Primary or below

1830 (10.9)

1030 (56.3)^a

288 (15.7)^a

391 (21.4)^b

121 (6.6)^b

 Junior middle school

6211 (36.9)

3643 (58.7)^a

1084 (17.5)^a

1164 (18.7)^a

320 (5.2)^a

 Senior middle school

4902 (29.1)

2823 (57.6)^a

979 (20.0)^b

867 (17.7)^a

233 (4.8)^a,b

 College or above

3910 (23.2)

2337 (59.8)^a

722 (18.5)^a

682 (17.4)^a

169 (4.3)^a

Mother’s education level

49.51

 Primary or below

2423 (14.4)

1441 (59.5)^a

354 (14.6)^b

487 (20.1)^a

141 (5.8)^a

 Junior middle school

6151 (36.5)

3642 (59.2)^a

1082 (17.6)^a

1119 (18.2)^a

308 (5.0)^a

 Senior middle school

4634 (27.5)

2606 (56.2)^a

914 (19.7)^b

882 (19.0)^a,b

232 (5.0)^b

 College or above

3645 (21.6)

2144 (58.8)^a,b

723 (19.8)^b

616 (16.9)^a

162 (4.4)^a

Family economic level

 Poor

2119 (12.6)

1094 (51.6)^a

287 (13.5)^b

579 (27.3)^c

159 (7.5)^c

 Fair

11,677 (69.3)

7031 (60.2)^a

2097 (18.0)^b

2057 (17.6)^b

492 (4.2)^c

 Good

3057 (18.1)

1708 (55.9)^a

689 (22.5)^b

468 (15.3)^c

192 (6.3)^b

Number of friends

 0

553 (3.3)

228 (41.2)^a

64 (11.6)^a

164 (29.7)^b

97 (17.5)^c

 1–2

4096 (24.3)

2320 (56.6)^a

573 (14.0)^b

1002 (24.5)^c

201 (4.9)^a

 3–5

6949 (41.2)

4294 (61.8)^a

1198 (17.2)^b

1168 (16.8)^b

289 (4.2)^b

  ≥ 6

5255 (31.2)

2991 (56.9)^a

1238 (23.6)^b

770 (14.7)^c

256 (4.9)^a

Self-evaluation of academic performance

308.02

 < 0.001

 Poor

4087 (24.3)

1966 (48.1)^a

800 (19.6)^b

994 (24.3)^c

327 (8.0)^d

 Medium

10,316 (61.2)

6312 (61.2)^a

1864 (18.1)^b

1732 (16.8)^c

408 (4.0)^d

 Good

2450 (14.5)

1555 (63.5)^a

409 (16.7)^b

378 (15.4)^b

108 (4.4)^a,b