Table 1 Sample characteristics at entry into the study, with comparison to the community sample

Age: baseline

17.34 (0.45)

17.49 (0.34)

t(1125) = 3.08, p < 0.005

Sex: female (n, %)

31 (59%)

600 (56%)

p = 0.67

*Achieved 5/+ GCSEs A*-C

21 (46%)

1068 (86%)

χ² = 35.65, p < 0.0001, V = 0.422

*Left school before compulsory age

10 (19%)

-

-

*Arrested before baseline

21 (39%)

-

-

*IQ^a

97.41 (15.84)

105.74 (16.42; n = 277)

t(328) = 3.4, p < 0.005

*Verbal IQ

96.71 (19.85)

107.59 (16.72; n = 277)

t(323) = 4.14, p < 0.001

Performance IQ

98.04 (15.58)

101.37 (17.61; n = 277)

p = 0.21

*GE

37 (70%)

1014 (97%)

χ² = 26.46, p < 0.0001, V = 0.36