Table 3.

Language and literacy measures: Internal reliability. (Cronbach’s alpha); descriptive statistics in control (n = 72) and family-risk (n = 111) groups; tests of group difference and effect sizes.

		Control					Family-Risk
	Cronbach’s α	M (SD)	Min	Max	Skewness	Kurtosis	M (SD)	Min	Max	Skewness	Kurtosis	t	Cohen’s d
Age 5
Expressive vocabularya	.84	31.88 (5.95)	20	47	.20	−.54	25.78 (10.05)	2	46	−.50	−.14	5.25***	.75
Sentence structurea	.66	21.74 (2.84)	14	26	−.71	−.10	20.48 (3.83)	9	26	−.91	.30	2.55*	.37
Phoneme isolationa	.91	14.00 (3.13)	4	16	−2.17	4.14	12.46 (4.29)	0	16	−1.38	1.07	2.84**	.41
Phoneme deletiona	.93	7.74 (2.26)	2	12	−.03	−.48	6.41 (2.62)	0	12	−.12	−.29	3.57***	.55
Letter-sound knowledgea	.98	30.18 (4.06)	9	32	−3.79	15.21	28.94 (4.25)	8	32	−2.57	7.87	1.97	.30
Early word recognitiona	.98	20.36 (8.04)	0	30	−.65	−.31	14.98 (8.90)	0	30	.28	−.96	4.19***	.58
Single word readinga	.98	14.64 (9.75)	0	37	.54	−.35	8.87 (9.79)	0	44	1.31	1.12	3.95***	.57
Age 6
Early word recognitiona	.98	27.56 (4.86)	8	30	−.93	−.21	22.03 (8.37)	1	30	−.93	−.21	5.72***	.81
Single word readinga	.98	27.86 (10.29)	0	49	−.45	.35	18.87 (13.12)	0	55	.55	−.62	5.23***	.77
Nonword readinga	.96	12.85 (4.76)	0	20	−.54	−.29	8.22 (6.37)	0	20	.28	−1.28	5.63***	.82
Spellinga	.71	6.19 (2.77)	0	10	−.04	1.26	4.69 (2.77)	0	10	.55	−.58	3.65***	.55
Reading comprehensiona	.64	16.57 (5.14)	0	23	−1.50	2.20	11.02 (7.02)	0	23	.17	−1.29	6.19***	.90

^aRaw scores.

*p < .05. **p < .01. ***p < .001.