Table 4 Effect Sizes by Participant Group and Disability Type (N= 23, k =111)

	Category	No. of studies (N)	k1)	Mean PND	Mean IRD	Mean Tau-U
Participants	Early childhood	16	72	.916	.934	.944
	Elementary school	7	39	.995	.995	.997
Disability type	ADHD (including at-risk & suspected cases)	4	24	1.000	1.000	1.000
	Developmental delay	8	40	.911	.923	.930
	Language developmental delay	1	2	.700	.729	.754
	Autism spectrum disorder	6	21	.915	.952	.972
	At risk for disability	2	9	.979	.979	.988
	Intellectual disability	3	15	.993	.993	.993

k : number of AB comparison units
(a single study could include multiple disability types, the sum of the number of studies by disability type may not equal the total number of studies)