LLMs Struggle with Faithful Data-Science Chart Generation

Jiahui tang, Kuicai Dong, Dexun Li, Hongchao Gu, Haocheng Yu, Wei Han, Chen Zhang, Yong Liu, Hao Wang, Enhong Chen· August 28, 2026 View original

Key takeaways

  • LLMs can generate visually plausible charts but often hallucinate data.
  • DEEPCHART benchmark reveals common errors in data extraction and quantitative reasoning.
  • Larger context windows alone won't solve data-level hallucinations in chart generation.
  • Human oversight and robust validation are crucial for LLM-generated visualizations.

Who benefits

Data AnalyticsBusiness IntelligenceFinanceResearchConsulting

Summary

A new benchmark, DEEPCHART, reveals that while large language models can produce visually plausible charts, they frequently suffer from data-level hallucinations. The study evaluates LLMs across extraction, reasoning, and visualization stages, finding common errors in realistic long and multimodal contexts, indicating that larger context windows alone are insufficient for faithful chart generation.

Large Language Models (LLMs) are increasingly capable of generating charts from data science instructions, often producing visualizations that appear correct at first glance. However, a new benchmark called DEEPCHART highlights a significant gap: these visually plausible charts frequently contain data-level hallucinations, meaning the underlying data or calculations are incorrect. DEEPCHART, an expert-annotated dataset of 1,482 chart-generation instances from real-world scientific papers and financial reports, breaks down the process into three stages: source-data extraction, derived-data reasoning, and chart rendering. Experiments with leading models show that errors are common in the extraction and reasoning phases, especially in complex, long, and multimodal inputs. This suggests that simply expanding context windows will not solve the problem; LLMs need improved capabilities for reliable evidence extraction and quantitative reasoning to achieve truly faithful chart generation.

Why it matters

Professionals relying on LLMs for data analysis and visualization must be aware of the potential for subtle, data-level hallucinations, which can lead to incorrect conclusions and flawed decision-making.

How to implement this in your domain

  1. 1Implement rigorous human review processes for any charts generated by LLMs, especially those used for critical decision-making.
  2. 2Develop internal validation checks to cross-reference LLM-generated chart data with original source data.
  3. 3Educate teams on the limitations of current LLMs in quantitative reasoning and data extraction for visualization.
  4. 4Explore hybrid approaches where LLMs suggest chart types or initial data transformations, but human experts or traditional BI tools handle final data processing and rendering.
  5. 5Contribute to or utilize benchmarks like DEEPCHART to evaluate the fidelity of LLM-based data visualization tools.

Original post by Jiahui tang, Kuicai Dong, Dexun Li, Hongchao Gu, Haocheng Yu, Wei Han, Chen Zhang, Yong Liu, Hao Wang, Enhong Chen

"arXiv:2608.26757v1 Announce Type: new Abstract: Faithful chart generation in real-world data-science workflows requires grounding visualizations in scattered evidence, computing chart-ready quantities, and rendering them accurately. Modern LLMs can produce visually plausible, ins…"

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Originally posted by Jiahui tang, Kuicai Dong, Dexun Li, Hongchao Gu, Haocheng Yu, Wei Han, Chen Zhang, Yong Liu, Hao Wang, Enhong Chen on X · view source

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