Table 1 Sample characteristics at each wave

Total children, n

4,176

4,043

4,084

4,027

3,873

3,497

3,071

Child characteristics

 Age, mean (SD)

4.7 (0.21)

6.8 (0.24)

8.7 (0.24)

10.8 (0.29)

12.8 (0.31)

14.8 (0.34)

16.9 (0.37)

 Sex, male, n (%)

2,137 (51.1)

2,066 (51.1)

2,091 (51.2)

2,054 (51.0)

1,978 (51.0)

1,777 (50.8)

1,568 (51.0)

 HRQoL (PedsQL), mean (SD)

80.7 (10.4)

80.4 (11.9)

80.1 (12.2)

78.9 (14.2)

81.1 (13.5)

79.4 (15.1)

80.2 (14.1)

 Mental health (SDQ), mean (SD)

9.1 (5.2)

7.8 (5.0)

7.5 (5.3)

7.9 (5.5)

7.4 (5.5)

7.1 (5.4)

7.2 (5.5)

  Low (< 13), n (%)

3,212 (77.0)

3,273 (82.8)

3,105 (84.1)

3,268 (81.6)

3,184 (83.7)

2,843 (84.6)

2,510 (84.0)

  Borderline/query (13–16), n (%)

554 (13.2)

434 (10.9)

339 (9.1)

415 (10.3)

330 (8.6)

291 (8.6)

242 (8.1)

  Abnormal/concern, (17 +), n (%)

403 (9.6)

243 (6.1)

246 (6.6)

318 (7.9)

287 (7.5)

225 (6.7)

235 (7.8)

 Physical health problem^a, n (%)

1,657 (39.6)

1,584 (39.1)

2,158 (52.8)

2,544 (63.1)

2,415 (62.3)

2,229 (63.7)

2,009 (65.4)

 Language other than English, n (%)

425 (10.1)

405 (10.0)

407 (9.9)

397 (9.8)

307 (7.9)

337 (9.6)

291 (9.5)

Parent characteristics

 Parent 1 sex, female, n (%)

4,065 (97.3)

3,937 (97.3)

3,976 (97.3)

3,918 (97.2)

3,767 (97.2)

3,402 (97.2)

2,985 (97.2)

 Parent 2 sex, male, n (%)

3,598 (97.5)

3,496 (97.5)

3,532 (97.5)

3,488 (97.4)

3,359 (97.4)

3,059 (97.4)

2,697 (97.2)

 Either parent completed higher education, n (%)

2,153 (51.9)

2,088 (52.1)

2,187 (54.4)

2,220 (55.9)

2,217 (57.9)

2,036 (58.6)

1,823 (59.7)

 Either parent probable serious mental illness (Kessler 6), n (%)

171 (5.1)

122 (3.7)

139 (4.5)

154 (4.8)

151 (5.1)

127 (4.6)

145 (6.3)

Family characteristics

 Either parent maladaptive parenting (low warmth, high hostility), n (%)

446 (12.4)

272 (8.1)

334 (10.6)

426 (13.0)

474 (15.7)

441 (15.7)

293 (13.9)

 Argumentative parental relationship, as rated by either parent, n (%)

731 (20.3)

577 (16.7)

481 (15.2)

520 (15.7)

502 (16.4)

433 (15.0)

406 (17.0)

 Any violence in parental relationship, as rated by either parent, n (%)

378 (10.6)

301 (8.9)

261 (8.4)

238 (7.3)

228 (7.7)

202 (7.1)

157 (6.7)

 Number of siblings, mean (SD)

1.4 (0.9)

1.5 (0.9)

1.6 (1.0)

1.6 (1.0)

1.5 (1.0)

1.4 (1.0)

1.3 (1.0)

 Household income, $AUD, mean (SD)

77,484.75 (47,386.28)

88,115.54 (62,026.12)

101,858.80 (68,669.39)

110,088.80 (75,791.77)

123,372.60 (86,976.03)

134,479.60 (91,421.19)

149,420.10 (100,911.40)

Neighbourhood characteristics

 SEIFA IRSAD^b, mean (SD)

1007.5 (78.4)

1011.2 (73.9)

1012.0 (74.1)

1013.0 (75.0)

1011.6 (73.3)

1013.8 (72.8)

1013.0 (76.1)

 Remoteness, Major Cities, n (%)

2,702 (64.8)

2,616 (64.7)

2,622 (64.3)

2,569 (64.0)

2,458 (63.4)

2,221 (63.5)

1,966 (64.0)