Non-referred Mean ± SEM	Referred Mean ± SEM	t test	P	Effect size Cohen’s d
Matrix Reasoning	0.14 ± 0.08	−0.64 ± 0.05	8.34	7.9x10−16	0.83
Vocabulary	0.85 ± 0.08	−0.02 ± 0.06	8.11	4.31x10−15	0.81
Alliteration	−0.08 ± 0.03	−0.54 ± 0.03	7.93	1.5x10−14	0.79
Forward Digit	0.43 ± 0.08	−0.45 ± 0.06	8.4	5.5x10−16	0.84
Dot Matrix	0.30 ± 0.08	−0.56 ± 0.05	8.6	2.2x10−16	0.86
Backward Span	0.31 ± 0.09	−0.51 ± 0.04	9.3	2.2x10−16	0.93
Mister X	0.57 ± 0.09	−0.18 ± 0.05	7.3	1.0x1012	0.73
Literacy	0.33 ± 0.07	−1.08 ± 0.05	15.79	2.2x10−16	1.58
Numeracy	0.31 ± 0.09	−0.86 ± 0.06	10.037	2.2x10−16	1

Mean and standard errors for referred and non-referred samples. All scores are given as z scores, relative to the age standardized normative sample for each test.