Having older classmates boosts a child’s test scores but increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD¶

Claim · All claims
Evidence · 1 study · associational r? · q3
Currency · newest study 2009 · checked against its sources 2026-10-20 (automated, 1 of 1 entry) · not reviewed by a person

Subclaims¶

Reading the evidence codes

q is the design tier, i the impact, n the sample, and the kind with its r the rigour judged within that kind: what each code means.

This claim: no standardized effect is recorded in observations/ for it yet, so no benchmark reading is possible.

q3 i? Having older classmates boosts a child’s test scores. → Todd E. Elder and Darren H. Lubotsky 2009 q3 i? Having older classmates increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD. → Todd E. Elder and Darren H. Lubotsky 2009

Evidence¶

Todd E. Elder and Darren H. Lubotsky 2009¶

Todd E. Elder and Darren H. Lubotsky. (2009). Kindergarten Entrance Age and Children’s Achievement: Impacts of State Policies, Family Background, and Peers. Journal of Human Resources. https://doi.org/10.3368/jhr.44.3.641

q3 · i? · associational · r?

The article reports peer-age effects with offsetting signs: older classmates “boost a child’s test scores” while also increasing grade repetition and learning-disability diagnoses such as ADHD. Both outcomes are stated in the same finding. No effect size is printed in the available text.

"Finally, having older classmates boosts a child’s test scores but increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD."

Discussion¶

Learner Variables¶

Attention — outcome: instruction changes it
Age and Developmental Stage — predictor: learners who differ on it differ in outcomes

Being a year older at kindergarten entry leads to higher initial achievement — the general claim this finding bears on, with the studies behind it
A relationship exists between students' relative age among their peers and their probability of disability classification — related
An additional month of relative age among peers decreases the likelihood of receiving special education services by 2-5 percent — related
LCFF-induced spending increases reduced the probability of grade repetition, particularly in elementary school — related
At the end of first grade, children whose kindergarten entry was delayed were behind their classmates who began kindergarten on time in math — related

Page metadata

Field	Value
`type`	`claim`
`id`	`older-classmates-boost-scores-increase-repetition-and-disability-diagnoses`
`title`	`Having older classmates boosts a child’s test scores but increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD`
`description`	`Having older classmates boosts a child’s test scores but increases the probability of grade repetition and diagnoses of learning disabilities such as ADHD`
`status`	`review`
`evidence_strength`	`moderate`
`newest_evidence`	`2009`
`source_checked`	`2026-10-20`
`generated`	by `process:wiki-ingest` on `2026-10-15`
`trust`	unverified — no one has confirmed this page's content
`sources`	1 — `todd-e-elder-and-darren-h-lubotsky-2009`

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