Table 1.
Descriptive statistics: Study context, design, outcome assessment, participants, and intervention characteristics for intervention‐control studies included in the meta‐analysis
| Study characteristics | k | I | n | Mean i | SD i | Range i |
|---|---|---|---|---|---|---|
| Study context | ||||||
| % performed in the United States | 195 | 327 | 1334 | 0.86 | 0.35 | 0–1 |
| Participants | 195 | 327 | 1334 | 280.34 | 1276.94 | 15–21,317 |
| Districts | 147 | 240 | 959 | 2.91 | 5.03 | 1–27 |
| Schools | 177 | 295 | 1213 | 12.18 | 13.92 | 1–147 |
| Study design and implementation | ||||||
| % QES | 195 | 327 | 1334 | 0.07 | 0.26 | 0–1 |
| % Implementation problems | 177 | 285 | 1172 | 0.11 | 0.32 | 0–1 |
| Outcome assessment | ||||||
| % General test* | 195 | 327 | 1334 | 0.09 | 0.28 | 0–1 |
| % Follow‐up test* | 195 | 327 | 1334 | 0.22 | 0.41 | 0–1 |
| Participant characteristics | ||||||
| % Girls | 167 | 290 | 1254 | 44.58 | 10.03 | 0–65 |
| Grade | 195 | 327 | 1334 | 2.36 | 1.83 | 0–7 |
| % Minority | 154 | 271 | 1139 | 65.49 | 27.28 | 0–100 |
| % Low income | 120 | 192 | 802 | 69.48 | 21.11 | 12.1–100 |
| General intervention characteristics | ||||||
| % Mathematics tests* | 195 | 327 | 1334 | 0.18 | 0.38 | 0–1 |
| Duration in weeks | 194 | 326 | 1329 | 23.11 | 18.01 | 1–160 |
| Number of sessions | 177 | 298 | 1280 | 69.08 | 62.14 | 3–400 |
| Hours per week | 178 | 299 | 1286 | 1.95 | 1.49 | 0.22–10 |
| Implemented by school staff | 192 | 320 | 1325 | 0.51 | 0.50 | 0–1 |
| Instructional methods | ||||||
| Coaching personnel | 195 | 327 | 1334 | 0.11 | 0.31 | 0–1 |
| Computer‐assisted instruction | 195 | 327 | 1334 | 0.15 | 0.36 | 0–1 |
| Incentives | 195 | 327 | 1334 | 0.09 | 0.29 | 0–1 |
| Medium‐group instruction | 195 | 327 | 1334 | 0.06 | 0.25 | 0–1 |
| Other method | 195 | 327 | 1334 | 0.02 | 0.15 | 0–1 |
| Peer‐assisted instruction | 195 | 327 | 1334 | 0.15 | 0.36 | 0–1 |
| Progress monitoring | 195 | 327 | 1334 | 0.13 | 0.33 | 0–1 |
| Small‐group instruction | 195 | 327 | 1334 | 0.65 | 0.48 | 0–1 |
| Content domain | ||||||
| Comprehension | 195 | 327 | 1334 | 0.41 | 0.49 | 0–1 |
| Decoding | 195 | 327 | 1334 | 0.51 | 0.50 | 0–1 |
| Fluency | 195 | 327 | 1334 | 0.30 | 0.46 | 0–1 |
| Multiple reading | 195 | 327 | 1334 | 0.55 | 0.50 | 0–1 |
| Spelling and writing | 195 | 327 | 1334 | 0.23 | 0.42 | 0–1 |
| Vocabulary | 195 | 327 | 1334 | 0.26 | 0.44 | 0–1 |
| Algebra and pre‐algebra | 195 | 327 | 1334 | 0.08 | 0.27 | 0‐1 |
| Fractions | 195 | 327 | 1334 | 0.03 | 0.17 | 0–1 |
| Geometry | 195 | 327 | 1334 | 0.07 | 0.25 | 0–1 |
| Multiple math | 195 | 327 | 1334 | 0.24 | 0.43 | 0–1 |
| Number sense | 195 | 327 | 1334 | 0.15 | 0.35 | 0–1 |
| Operations | 195 | 327 | 1334 | 0.15 | 0.36 | 0–1 |
| Problem solving | 195 | 327 | 1334 | 0.10 | 0.30 | 0–1 |
| General academic skills | 195 | 327 | 1334 | 0.04 | 0.19 | 0–1 |
| Meta‐cognitive strategies | 195 | 327 | 1334 | 0.13 | 0.33 | 0–1 |
| Social‐emotional skills | 195 | 327 | 1334 | 0.05 | 0.22 | 0–1 |
| Single component interventions | ||||||
| Coaching personnel | 195 | 327 | 1334 | 0.01 | 0.10 | 0–1 |
| Computer‐assisted instruction | 195 | 327 | 1334 | 0.06 | 0.23 | 0–1 |
| Incentives | 195 | 327 | 1334 | 0.01 | 0.11 | 0–1 |
| Medium‐group instruction | 195 | 327 | 1334 | 0.04 | 0.19 | 0‐1 |
| Peer‐assisted instruction | 195 | 327 | 1334 | 0.07 | 0.26 | 0–1 |
| Progress monitoring | 195 | 327 | 1334 | 0.01 | 0.10 | 0–1 |
| Small‐group instruction | 195 | 327 | 1334 | 0.47 | 0.50 | 0–1 |
| Comprehension | 195 | 327 | 1334 | 0.02 | 0.13 | 0–1 |
| Decoding | 195 | 327 | 1334 | 0.10 | 0.31 | 0–1 |
| Fluency | 195 | 327 | 1334 | 0 | 0 | 0 |
| Spelling and writing | 195 | 327 | 1334 | 0 | 0 | 0 |
| Vocabulary | 195 | 327 | 1334 | 0.00 | 0.06 | 0–1 |
| Algebra/pre‐algebra | 195 | 327 | 1334 | 0 | 0 | 0‐1 |
| Fractions | 195 | 327 | 1334 | 0.00 | 0.06 | 0–1 |
| Geometry | 195 | 327 | 1334 | 0 | 0 | 0 |
| Operations | 195 | 327 | 1334 | 0.01 | 0.11 | 0–1 |
| Number sense | 195 | 327 | 1334 | 0.03 | 0.18 | 0–1 |
| Problem solving | 195 | 327 | 1334 | 0.00 | 0.06 | 0–1 |
| General academic skills | 195 | 327 | 1334 | 0.00 | 0.06 | 0–1 |
| Meta‐cognitive strategies | 195 | 327 | 1334 | 0 | 0 | 0 |
| Social‐emotional skills | 195 | 327 | 1334 | 0.01 | 0.08 | 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, except for variables marked with *. As these variables differ within interventions, we averaged on the effect size level.
Abbreviation: QES, quasi‐experimental studies.