All four meta-analysable STAR studies report positive, statistically significant effects of small classes, but average effects are small¶

Claim · All claims
Evidence · 1 study · quant-synthesis r3 · q3 · i1 small
Currency · newest study 2018 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i1 Study-level effect sizes from STAR data analyses ranged 0.17 to 0.34 for reading and 0.15 to 0.33 for mathematics, all favouring the treated and all statistically significant. → Filges 2018

Evidence¶

Filges 2018¶

Filges, T., Sonne‐Schmidt, C. S., Nielsen, B. C. V. (2018). Small class sizes for improving student achievement in primary and secondary schools: a systematic review. Campbell Systematic Reviews 2018:10. https://doi.org/10.4073/csr.2018.10

q3 · i1 · quant-synthesis · r3

Synthesis of four studies analysing the Tennessee STAR RCT data (class size reduction in grades K–3), with effect sizes and standard errors corrected for clustering using an intra-cluster correlation of ρ = 0.22; study-level effect sizes ranged 0.17–0.34 (reading) and 0.15–0.33 (mathematics), all statistically significant.

"All reported results from the four studies analysing STAR data indicated a positive effect favouring the treated; all of the study‐level effects were statistically significant. The study‐level effect sizes for reading varied between 0.17 and 0.34 and the study‐level effect sizes for mathematics varied between 0.15 and 0.33."

Discussion¶

Related Claims¶

• Class size reduction shows a negative, statistically non-significant effect on mathematics achievement (pooled SMD ‐0.03) — reports the opposite
• Class size reduction produces a small, statistically significant positive effect on reading achievement by end of treatment year (pooled SMD 0.11) — related