The Gift of Time? School Starting Age and Mental Health
Dee, T. S., & Sievertsen, H. H. · 2018
grade Bquasi-experimentindependentunreplicatednumbers spot-checked
Sample
8,092 Danish children
Population
Danish National Birth Cohort linked to registers, 30-day window around the January 1 cutoff.
Design
Fuzzy regression discontinuity; outcome is the SDQ mental-health instrument at ages 7 and 11.
Key findings
The strongest evidence for a GENUINE (non-artifactual) benefit of starting later: a large, persistent reduction in inattention/hyperactivity, concentrated in girls and specific to that subscale. This is a maturational self-regulation effect, distinct from the test-score relative-age artifact.
Counterfactual
Children entering a year later due to the cutoff rule.
Genetic confound
RD on birth date.
Replication notes
The effect's specificity to one subscale, and its persistence to age 11, distinguish it from the ADHD-labelling artifact documented by Elder.
DOI / URL
10.1002/hec.3638
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| Inattention/hyperactivity at age 7 | SD | -0.73 | mixed | grade-3 | business-as-usual | 1-2yr | non-cognitive |
| Inattention/hyperactivity at age 11 | SD | -0.69 — persists four years later | mixed | grade-6+ | business-as-usual | over-2yr | non-cognitive |
| Other SDQ subscales (emotional, conduct, peer, prosocial) | SD | ~null — the specificity argues against a generic reference-bias artifact | mixed | grade-3 | business-as-usual | 1-2yr | non-cognitive |
Cited by
- School starting age, relative age, and academic redshirtingmixedconf: highgc: low