High Scores, Hidden Failures: Evaluating Codebook-Based LLM Content Analysis

Elena Senger, Yuri Campbell, Rob Van Der Goot, Barbara Plank


Abstract
Large language models (LLMs) are increasingly used for codebook-based content analysis in computational social science, where codebooks translate theoretical concepts into labeling schemes. While prior work reports strong predictive performance, it remains unclear whether these systems produce reliable and robust annotations. We conduct a large-scale empirical failure-mode analysis of LLM-based coding pipelines across three datasets and five models by systematically evaluating their stability, robustness, and conceptual validity under controlled perturbations, domain shifts, and optimization procedures. We uncover multiple failures that are largely invisible under standard metrics, showing that high aggregate scores frequently coexist with severe label-level disparities, instability across runs, domain sensitivity, and shifts in label interpretation. Importantly, these failure modes persist under widely used optimization strategies and remain largely invisible under standard metrics such as accuracy and micro-F1. Our results demonstrate that current LLM-based coding pipelines cannot be treated as stable measurement tools without targeted validation beyond aggregate performance.
Anthology ID:
2026.findings-emnlp.88
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1805–1820
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.88/
DOI:
Bibkey:
Cite (ACL):
Elena Senger, Yuri Campbell, Rob Van Der Goot, and Barbara Plank. 2026. High Scores, Hidden Failures: Evaluating Codebook-Based LLM Content Analysis. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 1805–1820, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
High Scores, Hidden Failures: Evaluating Codebook-Based LLM Content Analysis (Senger et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.88.pdf