When One Benchmark Hides Many Truths: Mixture-IRT and LLM Difficulty Prediction

Enis Dogan, Burhan Ogut


Abstract
Studies that validate LLM-predicted item difficulty conventionally benchmark predictions against a single-population estimate. Using a multimodal LLM’s pairwise judgments on a 29-item mathematics exam, mixture Rasch modeling shows the LLM tracks difficulty ordering differentially across classes, meaningful subgroup variation that the aggregate benchmark conceals entirely.
Anthology ID:
2026.aimecon-wip.36
Volume:
Proceedings of the Artificial Intelligence in Measurement and Education Conference (AIME-Con): Works in Progress
Month:
October
Year:
2026
Address:
Wyndham Grand Pittsburgh Downtown, Pittsburgh, Pennsylvania, United States
Editors:
Joshua Wilson, Christopher Ormerod, Magdalen Beiting-Parrish
Venue:
AIME-Con
SIG:
Publisher:
National Council on Measurement in Education (NCME)
Note:
Pages:
282–288
Language:
URL:
https://aclanthology.org/2026.aimecon-wip.36/
DOI:
Bibkey:
Cite (ACL):
Enis Dogan and Burhan Ogut. 2026. When One Benchmark Hides Many Truths: Mixture-IRT and LLM Difficulty Prediction. In Proceedings of the Artificial Intelligence in Measurement and Education Conference (AIME-Con): Works in Progress, pages 282–288, Wyndham Grand Pittsburgh Downtown, Pittsburgh, Pennsylvania, United States. National Council on Measurement in Education (NCME).
Cite (Informal):
When One Benchmark Hides Many Truths: Mixture-IRT and LLM Difficulty Prediction (Dogan & Ogut, AIME-Con 2026)
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PDF:
https://aclanthology.org/2026.aimecon-wip.36.pdf