EssayCBM: Rubric-Aligned Concept Bottleneck Models for Transparent Essay Grading
Kumar Satvik Chaudhary, Chengshuai Zhao, Fan Zhang, Yung Hin Tse, Garima Agrawal, Yuli Deng, Huan Liu
TL;DR
Automated essay grading often remains a black box despite competitive accuracy. The authors propose EssayCBM, a rubric-aligned Concept Bottleneck Model that first predicts eight rubric concepts $C=\\\ o c_1,\\dots, c_8\\$ from essays and then computes the final grade via $\\hat{Y} = h(C)$, providing a transparent trace from rubric criteria to score. The model is trained end-to-end with $\\mathcal{L}_{\\text{total}} = \\mathcal{L}_{\\text{grade}} + \\lambda \\mathcal{L}_{\\text{concept}}$ and supports multiple encoders (e.g., BERT-base, RoBERTa-base, GPT-2, BiLSTM). It is deployed as an open-source web application with a Streamlit frontend and FastAPI backend, offering real-time rubric-aligned feedback, confidence scores, and human-in-the-loop correction. The results show that EssayCBM matches black-box performance while delivering actionable, concept-level explanations that can enhance formative feedback and trust in automated assessment.
Abstract
Understanding how automated grading systems evaluate essays remains a significant challenge for educators and students, especially when large language models function as black boxes. We introduce EssayCBM, a rubric-aligned framework that prioritizes interpretability in essay assessment. Instead of predicting grades directly from text, EssayCBM evaluates eight writing concepts, such as Thesis Clarity and Evidence Use, through dedicated prediction heads on an encoder. These concept scores form a transparent bottleneck, and a lightweight network computes the final grade using only concepts. Instructors can adjust concept predictions and instantly view the updated grade, enabling accountable human-in-the-loop evaluation. EssayCBM matches black-box performance while offering actionable, concept-level feedback through an intuitive web interface.
