Table 1 Sample characteristics

Gender^a

6,571 (46.2%)

7,501 (52.8%)

81 (0.6%)

Ethnicity

 Asian

536 (8.5%)

829 (11.2%)

< 10

N/A

 Black

376 (6.0%)

418 (5.7%)

< 10

N/A

 Mixed

254 (4.0%)

295 (4.0%)

< 10

N/A

 Other

212 (3.4%)

215 (2.9%)

< 10

N/A

 White

4,923 (78.1%)

5,609 (76.2%)

58 (78.4%)

10,637(77.1%)

Ever being eligible to free school meals until 2016/17

 No

4,065 (64.5%)

4,782 (64.9%)

50 (67.6%)

8,942 (64.8%)

 Yes

2,236 (35.5%)

2,584 (35.1%)

24 (32.4%)

4,858 (35.2%)

Special education need status

 No

5,199 (83.8%)

6,723 (91.9%)

62 (84.9%)

12,039 (88.2%)

 Yes

1,003 (16.2%)

591 (8.1%)

11 (15.1%)

1,609 (11.8%)

Child in need status

 No

5,958 (94.6%)

6,999 (95.0%)

68 (91.9%)

N/A

 Yes

343 (5.4)

367 (5.0)

< 10

N/A

Total difficulties at baseline – Mean (SD), n

13.55 (6.34), 6,525

12.88 (6.39), 7,452

14.51 (6.19), 81

13.21 (6.38), 14,120

Emotional difficulties at baseline – Mean (SD), n

3.32 (2.39), 6,532

4.25 (2.52), 7,461

4.31 (2.48),

81

3.82 (2.50), 14,136

Behavioural difficulties at baseline – Mean (SD), n

2.82 (2.10), 6,536

2.12 (1.92), 7,467

2.43 (1.86), 81

2.45 (2.03), 14,146