The Evidence on Teaching

Not Too Late: Improving Academic Outcomes Among Adolescents (Saga/Match high-dosage tutoring, two Chicago RCTs)

Guryan, J., Ludwig, J., Bhatt, M. P., Cook, P. J., et al. · 2023

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Sample
Study 1 N=2,633; Study 2 N=2,710 (internal replication)
Population
Low-income minority 9th-10th graders, Chicago public schools, 2-5 years behind in math.
Design
Two large individually-randomized trials; 2:1 tutoring, 55 min/day as a scheduled class period (~140-165 hrs/yr); paraprofessional tutors (~$17k stipend). Published AER 113(3) — numbers below are the published version (the working paper's were slightly lower).
Key findings
The best evidence in the tutoring literature: replicated large RCTs, independent standardized outcomes, and measured persistence (+0.23 SD 1-2 years later). Daily in-school 2:1 tutoring roughly doubles-to-triples a year of normal high-school math learning at $3,200-4,800/student (~1/5 of per-pupil spending). Also proves the 'too late after early childhood' claim wrong.
Genetic confound
Randomized. Gains are taught-domain math skills; low-performing-sample SD units modestly inflate d vs population.
Replication notes
Internal replication succeeded. Independent scale-ups shrink (Nashville 0.00-0.09; UK NTP ~0.03-0.09).
Cost
$3,200-4,800/student/yr during the study (later ~$1,800 with AmeriCorps subsidy); CPS spends ~$17,000/pupil.
DOI / URL
10.1257/aer.20210434

Effects

OutcomeMetricValueMeasureTimingVsHorizonClass
Math, Study 1SD (ACT EXPLORE/PLAN)ITT 0.09 / TOT 0.18standardizedend of year 1business-as-usualend-of-treatmentdomain-skill
Math, Study 2 (replication)SDTOT 0.40 (abstract range 0.18-0.40 across tests/norming)standardizedend of year 1business-as-usualend-of-treatmentdomain-skill
Persistence: 11th-grade math tests / math GPASD / GPA pts+0.23 SD / +0.25 (1-2 years post — rare persistence evidence, ~70% retained)standardized1-2yr follow-upbusiness-as-usual1-2yrdomain-skill
On-time graduationpp+1.3 (imprecise, ns)standardized2yr+ follow-upbusiness-as-usualover-2yrattainment

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