Table 1.

Descriptive statistics: Study context, design, outcome assessment, participants and intervention characteristics for studies included in the meta‐analysis

Study characteristics	k	i	n	Mean i	SD i	Range i
Study context
% performed in the United States	71	99	214	0.86	0.35	0–1
Participants	71	99	214	524.5	1300.1	16–9,187
Schools	63	85	193	7.7	14.3	1–121
Districts	57	81	186	2.0	2.41	1–10
Study design and implementation
% QES	71	99	214	0.24	0.43	0–1
% Implementation problems	71	99	214	0.35	0.48	0–1
Outcome assessment
% General test	71	99	214	0.45	0.47	0–1
% Follow‐up test	71	99	214	0.077	0.23	0–1
Participant characteristics
% Girls	65	93	200	47.1	14.8	0–100
Grade	71	99	214	8.3	1.33	6.7–11.5
% Minority	58	83	182	73.4	24.7	6–100
Low income	45	65	124	62.1	20.8	5–100
General intervention characteristics
% Mathematics tests	71	99	214	0.32	0.44	0–1
Duration in weeks	71	99	214	27.4	19.3	1–120
Number of sessions	56	77	182	75.3	88.0	5–480
Hours per week	53	70	176	2.95	3.62	0.6–30
Implemented by school staff	61	88	196	0.68	0.47	0–1
Implemented by researchers	61	88	196	0.20	0.41	0–1
Instructional methods
Coaching of personnel	71	99	214	0.25	0.44	0–1
CAI	71	99	214	0.22	0.42	0–1
Incentives	71	99	214	0.12	0.33	0–1
Other method	71	99	214	0.14	0.34	0–1
Peer‐assisted	71	99	214	0.29	0.46	0–1
Progress monitoring	71	99	214	0.25	0.44	0–1
Small group	71	99	214	0.33	0.47	0–1
Multiple instructional methods	71	99	214	0.46	0.50	0–1
Content domain
Comprehension	71	99	214	0.45	0.50	0–1
Decoding	71	99	214	0.30	0.46	0–1
Fluency	71	99	214	0.17	0.38	0–1
Spelling and writing	71	99	214	0.21	0.41	0–1
Vocabulary	71	99	214	0.34	0.48	0–1
Multiple reading areas	71	99	214	0.52	0.50	0–1
Algebra/prealgebra	71	99	214	0.10	0.30	0–1
Fractions	71	99	214	0.04	0.20	0–1
Geometry	71	99	214	0.03	0.17	0–1
Operations	71	99	214	0.04	0.20	0–1
Probability	71	99	214	0.02	0.14	0–1
Multiple math areas	71	99	214	0.16	0.37	0–1
Meta‐cognitive strategies	71	99	214	0.43	0.50	0–1
Social‐emotional skills	71	99	214	0.08	0.27	0–1
General academic skills	71	99	214	0.12	0.33	0–1
Single component interventions
Coaching of personnel	71	99	214	0.05	0.22	0–1
CAI	71	99	214	0.01	0.10	0–1
Incentives	71	99	214	0.04	0.20	0–1
Peer‐assisted	71	99	214	0.08	0.27	0–1
Progress monitoring	71	99	214	0	0	0
Small group	71	99	214	0.21	0.41	0–1
Comprehension	71	99	214	0.04	0.20	0–1
Decoding	71	99	214	0.03	0.17	0–1
Fluency	71	99	214	0	0	0
Spelling and writing	71	99	214	0	0	0
Vocabulary	71	99	214	0.01	0.10	0–1
Algebra/prealgebra	71	99	214	0.05	0.22	0–1
Fractions	71	99	214	0.04	0.20	0–1
Geometry	71	99	214	0	0	0
Operations	71	99	214	0	0	0
Probability	71	99	214	0	0	0
Meta‐cognitive strategies	71	99	214	0.09	0.08	0–1
Social‐emotional skills	71	99	214	0.01	0.01	0–1
General academic skills	71	99	214	0.02	0.02	0–1

Note: The number of studies that provided information about a variable is denoted k, the number of interventions i and the number of effect sizes n. The mean, standard deviation of the mean, and the range is taken over interventions.

Abbreviations: CAI, computer‐assisted instruction; QES, quasiexperimental study.