Group size moderates intervention effects: 1:1 interventions had effect sizes about 0.5 points higher than small-group interventions at 20 h of dosage¶

Claim · All claims
Evidence · 1 study · quant-synthesis r3 · q3 · i3 large
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i3 The main effect of group size was significant (β = 0.50, 95% CI [0.06, 0.94]), favoring 1:1 over small-group interventions. → Anna H. Miller 2025

Evidence¶

Anna H. Miller 2025¶

Anna H. Miller, Daniel R. Espinas, Daniel McNeish, & Marcia A. Barnes. (2025). Dosage Response in Intensive Mathematics Interventions for Early Elementary Students With or At-Risk for Mathematics Learning Disability. Educational Psychology Review, 37, 91. https://doi.org/10.1007/s10648-025-10070-y

q3 · i3 · quant-synthesis · r3

Moderator analysis (Model 3) across 163 effect sizes contributing to the group-size term (one whole-class study was masked out). The authors report "the average effect size for 1:1 interventions was 0.5 points greater than the average effect size for small-group interventions" at 20 h.

"The main effect of group size (small-group as the reference group) on effect sizes was significant (β = 0.50, 95% CI [0.06, 0.94]). At 20 h of intervention, holding the effects of other variables constant, the average effect size for 1:1 interventions was 0.5 points greater than the average effect size for small-group interventions."

Discussion¶

Related Claims¶

• Dosage significantly predicts intervention effects in a linear model (β = 0.03 per hour), but the dosage main effect is no longer significant after controlling for moderators — related
• Outcome proximity moderates the dose–response relation: distal outcomes outperform proximal outcomes at dosages at or below 5.43 h, while proximal outcomes exceed distal outcomes at or above 22.6 h — related