Retention‑Driven Score Gains

When a school or state forces low‑reading third graders to repeat the year, the fourth‑grade test taker pool becomes selectively stronger—raising average scores without genuine cohort learning. Policymakers and journalists can misread these compositional effects as educational miracles unless analyses explicitly adjust for retention and grade‑flow changes. — Misinterpreting such selection artifacts can make other states copy ineffective or harmful policies, misallocating funding and political capital in national education reform debates.