Large language models (LLMs) hold revolutionary potential to digitize and enhance the Health & Public Services (H&PS) industry. Despite their advanced linguistic abilities, concerns about accuracy, stability, and traceability still persist, especially in high-stakes areas such as transportation systems. Moreover, the predominance of English in LLM development raises questions about how they perform in non-English contexts. This study originated from a real world industrial GenAI application, introduces a novel cross-lingual benchmark dataset comprising nearly 99,869 real traffic incident records from Vienna (2013-2023) to assess the robustness of state-of-the-art LLMs (≥ 9) in the spatio vs temporal domain for traffic incident classification. We then explored three hypotheses — sentence indexing, date-to-text conversion, and German-to-English translation — and incorporated Retrieval Augmented Generation (RAG) to further examine the LLM hallucinations in both spatial and temporal domain. Our experiments reveal significant performance disparities in the spatio-temporal domain and demonstrate what types of hallucinations that RAG can mitigate and how it achieves this. We also provide open access to our H&PS traffic incident dataset, with the project demo and code available at Website https://sites.google.com/view/llmhallucination/home

Large language models (LLMs) have revolutionized various domains with their remarkable capabilities, but their massive parameter sizes pose significant challenges for fine-tuning and inference, especially in resource-constrained environments. Conventional compression methods often result in substantial performance degradation within LLMs and struggle to restore model quality during fine-tuning. To address this challenge, we present Bayesian Knowledge Distillation (BayesKD), a novel distillation framework meticulously designed for compact LLMs in resource-constrained fine-tuning scenarios. Departing from conventional LLM distillation methods that introduce time-consuming paradigms and fail to generalize in compressed LLM fine-tuning scenarios, our BayesKD develops the Logits Dual-Scaling, Knowledge Alignment Module, and Bayesian Distillation Optimization. In particular, our Logits Dual-Scaling strategy adaptively aligns the strength of the teacher’s knowledge transfer, while the Knowledge Alignment Module bridges the gap between the teacher and student models by projecting their knowledge representations into a shared interval. Additionally, we employ Logits-Aware Bayesian Optimization to swiftly identify optimal settings based on these strategies, thereby enhancing model performance. Extensive experiments across diverse tasks demonstrate that BayesKD consistently outperforms baseline methods on various state-of-the-art LLMs, including LLaMA, Qwen2, Bloom, and Vicuna. Notably, our BayesKD achieves average accuracy gains of 2.99% and 4.05% over standard KD for the 8B parameter LLaMA and Qwen2 model. Codes are available in the supplementary materials.