The Evidence on Teaching

The Scaling Dynamics and Causal Effects of a District-Operated Tutoring Program (Metro Nashville)

Kraft, M. A., Edwards, D. S., & Cannata, M. · 2024

grade Bquasi-experimentindependentreplicated
Sample
>6,800 tutored students over 2.5 years (pilot RCT + cluster RCT + DiD)
Population
Metro Nashville grades 1-8, high-poverty urban district.
Design
The best-implemented district-run program: paid district teachers as tutors, standards-aligned, but modest dosage (12-18 hrs/yr vs Saga's ~150).
Key findings
Even with unusually good implementation, a district program at ~$1,500/student/yr and 12-18 delivered hours produced reading-only 0.04-0.09 and math zero. Dosage is the binding constraint — the efficacy numbers assume 100+ hours that district programs rarely deliver.
Genetic confound
Minimal.
Replication notes
Consistent with the Kraft-Schueler-Falken 1000+-student bin and with the Carbonari district nulls.
Cost
~$1,500/student/yr; tutor stipends = 80% of cost.
DOI / URL
10.26300/zcw7-4547

Effects

OutcomeMetricValueMeasureTimingVsHorizonClass
ReadingSD+0.04 to +0.09 (DiD 0.09 sig)standardizedend of yearbusiness-as-usualend-of-treatmentdomain-skill
MathSD~0.00 (null in all designs)standardizedend of yearbusiness-as-usualend-of-treatmentdomain-skill

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