Table 2.

Overall random effects weighted mean effect sizes for dialect and overall literacy, reading, and written language and moderator analyses.

	N	k	Effect size	95% Confidence interval		Test of heterogeneity
			r	Lower	Upper	Q	I2 (%)
All studies	2,007	20	−.28***	−.37	−.18	72.85***	74
All studies excluding Sligh & Conners (2003)	1,947	19	−.33***	−.39	−.26	35.30**	49
Studies with reading outcomes	1,947	19	−.32***	−.41	−.24	40.92**	56
Studies with print and/or phonological awareness outcomes	1,947	19	−.33***	−.41	−.25	38.41**	53
Studies with oral language outcomes	1,637	12	−.33***	−.41	−.23	36.69***	59
Studies with spelling and/or writing outcomes	429	8	−.22**	−.32	−.11	8.79	20
Moderators
SES						QModel	df	p value
Overall literacy						1.38	1	.24
Reading						1.83	1	.18
Grade Level	N	k	Effect size	95% Confidence interval		QBetween	df	p value
			r	Lower	Upper
Overall literacy
Primary (K–2)	1639	14	−.35***	−.41	−.27	0.73	1	.40
Intermediate (3–6)	308	5	−.27***	−.41	−.13
Reading
Primary (K–2)	1,639	14	−.35***	−.42	−.28	1.86	1	.17
Intermediate (3–6)	308	5	−.25**	−.39	−.09

Note. k = number of studies.

^** p < .01,

^*** p < .001.