The share of marks below the upper-second classification boundary fell by 24.7 percentage points, with effects significant at every threshold from 23 to 31 marks and at none above¶

Claim · All claims
Evidence · 1 study · causal r2 · q2
Currency · newest study 2026 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? At the upper-second boundary (30 of 50 marks), the treated half's share below the boundary fell from 23.5% to 10.6% while the untreated half's rose from 7.1% to 18.8%, a difference-in-differences of −24.7 percentage points (p = 0.001). → Dang 2026

Evidence¶

Dang 2026¶

Dang, C. T., & Nguyen, A. (2026). Verified, not generated: expert-verified AI study materials and the distribution of learning gains in a university course. https://arxiv.org/abs/2610.07097 doi:10.48550/arxiv.2610.07097

q2 · i? · causal · r2

Threshold difference-in-differences from linear probability models with HC1 errors on the same 340 examination marks. At the lower-second boundary the estimate is −12.9 points (p = 0.008); at the first-class boundary −2.4 points (p = 0.828).

"In shares, the treated half moved from 23.5% to 10.6% and the untreated half from 7.1% to 18.8%, a difference-in-differences of −24.7 percentage points (p = 0.001), equivalent to 21 students in a cohort of 85."

Discussion¶

Related Claims¶

• The average effect of verified AI materials attenuates when the lowest pre-intervention marks are removed, while the threshold effect at the upper-second boundary is robust — related
• Access to expert-verified AI study materials is associated with a 2.34-mark difference-in-differences advantage on a 50-mark examination component, reflecting protection from a decline rather than a rise — related
• Mark dispersion narrowed in the treated half alone, with the Part 2 standard deviation falling from 7.09 to 5.03 while Part 1's was unchanged — related
• Peers slightly under-mark their comrades' papers while self-assessors over-mark their own — related
• Gains from verified AI materials are concentrated in the bottom quintile, which accounts for roughly three-quarters of the average effect — related