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Main Authors: Deng, Haotian, Farber, Chris, Lee, Jiyoon, Tang, David
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2601.08843
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author Deng, Haotian
Farber, Chris
Lee, Jiyoon
Tang, David
author_facet Deng, Haotian
Farber, Chris
Lee, Jiyoon
Tang, David
contents Automated short-answer grading (ASAG) remains a challenging task due to the linguistic variability of student responses and the need for nuanced, rubric-aligned partial credit. While Large Language Models (LLMs) offer a promising solution, their reliability as automated judges in rubric-based settings requires rigorous assessment. In this paper, we systematically evaluate the performance of LLM-judges for rubric-based short-answer grading. We investigate three key aspects: the alignment of LLM grading with expert judgment across varying rubric complexities, the trade-off between uncertainty and accuracy facilitated by a consensus-based deferral mechanism, and the model's robustness under random input perturbations and adversarial attacks. Using the SciEntsBank benchmark and Qwen 2.5-72B, we find that alignment is strong for binary tasks but degrades with increased rubric granularity. Our "Trust Curve" analysis demonstrates a clear trade-off where filtering low-confidence predictions improves accuracy on the remaining subset. Additionally, robustness experiments reveal that while the model is resilient to prompt injection, it is sensitive to synonym substitutions. Our work provides critical insights into the capabilities and limitations of rubric-conditioned LLM judges, highlighting the importance of uncertainty estimation and robustness testing for reliable deployment.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08843
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Rubric-Conditioned LLM Grading: Alignment, Uncertainty, and Robustness
Deng, Haotian
Farber, Chris
Lee, Jiyoon
Tang, David
Computation and Language
Machine Learning
Automated short-answer grading (ASAG) remains a challenging task due to the linguistic variability of student responses and the need for nuanced, rubric-aligned partial credit. While Large Language Models (LLMs) offer a promising solution, their reliability as automated judges in rubric-based settings requires rigorous assessment. In this paper, we systematically evaluate the performance of LLM-judges for rubric-based short-answer grading. We investigate three key aspects: the alignment of LLM grading with expert judgment across varying rubric complexities, the trade-off between uncertainty and accuracy facilitated by a consensus-based deferral mechanism, and the model's robustness under random input perturbations and adversarial attacks. Using the SciEntsBank benchmark and Qwen 2.5-72B, we find that alignment is strong for binary tasks but degrades with increased rubric granularity. Our "Trust Curve" analysis demonstrates a clear trade-off where filtering low-confidence predictions improves accuracy on the remaining subset. Additionally, robustness experiments reveal that while the model is resilient to prompt injection, it is sensitive to synonym substitutions. Our work provides critical insights into the capabilities and limitations of rubric-conditioned LLM judges, highlighting the importance of uncertainty estimation and robustness testing for reliable deployment.
title Rubric-Conditioned LLM Grading: Alignment, Uncertainty, and Robustness
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2601.08843