英語ライティング評価における精度、公平性、学習者認識のための説明可能なAIフレームワーク

In the context of global educational digital transformation, automated writing evaluation (AWE) has been widely adopted due to its real-time and standardized advantages; however, traditional accuracy-oriented frameworks often neglect equity concerns and learners' perceptions, thereby limiting transparency and educational value. To address this limitation, this research proposes an explainable AI (XAI) framework designed to provide transparent and interpretable feedback, allowing learners to understand and trust automated evaluation, and integrates a multi-level validation model, the Three-Level Evaluation Framework (TLEF), spanning technical accuracy, group and individual equity, and learner perception, together with the AI Fairness Mediation Model (AFMM). Using stratified random sampling, data were collected from 764 multilingual learners (native speakers of English, Chinese, and Spanish) across Common European Framework of Reference for Languages (CEFR) levels A2 to C1 through writing tasks, dual scoring by AI and human experts, and structured questionnaires. Instead of listing individual tests, multiple statistical analysis was employed to examine validity, fairness, and the learner-perception relationship. Statistical analyses combined correlation, root mean square error (RMSE), Equalized Odds testing, and Structural Equation Modeling (SEM). The findings reveal that while the AI-assisted writing evaluation (AWE) system (ETS Criterion) achieves overall validity (r = 0.82), significant disparities remain: Chinese native speakers demonstrate the lowest agreement with human raters (0.72) and the highest RMSE (median 2.15), fairness biases are most pronounced at lower proficiency levels (ΔEO = 0.15 for A2 learners), and perceived fairness fully mediates the link between perceived accuracy and learner satisfaction, with proficiency moderating fairness sensitivity. By reframing fairness and perception as essential dimensions of explainability, the research enhances the theoretical grounding of AWE and provides a practical pathway for increasing transparency, equity, and social acceptance in educational technologies.