Explore the evidence
3 of 88 decisions · clear everything
Survives the gold standardIndependent, durable, rigorousThe debunked shelfCheap winsFor parents at homeFamous numbers, deflatedWhere we admit ignoranceThe terrain
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
who's delivering
group / setting
outcome class
The received wisdom that retention is harmful was two measurement errors, not a finding. Fix them and the achievement effect is zero — but the grade at which you hold a child back decides everything.
mixedconf: mediumgc: low19/1936/48
Grade retention — holding a child back versus promoting, and test-based promotion policies · retention · ages 5–18 · structure
Taking time away hurts measurably; adding it back buys almost nothing. The return per hour is ~0.02-0.03 SD, concave, and near zero in disorderly classrooms.
mixedconf: mediumgc: low23/2338/48
Length of the school day and year, time-on-task, extended time, and summer · time · ages 4–18 · structure
Coaching buys ~0.25 SD of score and has for 42 years — a fraction of what's advertised — and none of it is ability. The score moves; the construct doesn't.
mixedconf: mediumgc: medium20/2036/48
Test preparation — does coaching raise scores, and does a raised score mean raised ability? · assessment · ages 5–18 · structure
Not yet assessed for this question · 7
- Chronic absenteeism — does raising attendance raise achievement?
- Physical activity as an input — dose, fitness, and school outcomes
- Brain Gym, Whole Brain Teaching, and the smaller classroom brain fads
- Should Gardner's multiple intelligences be used as a basis for instruction?
- Breakfast, school meals, and micronutrients — what feeding children actually buys
- Perry Preschool and Abecedarian — what the famous studies actually establish
- Vision — outdoor time against myopia, and screening and correction for achievement
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