From Simulation to Reality: Validating Automated Evaluation of Conversational Agents

Justyna Gromada, Ekaterina Isakova, Joanna Brudnik, Alicja Kasicka, Natalia Krawczyk, Bartosz Przybył, Lukasz Krajewski, Michał K. Szczerbak


Abstract
Evaluating conversational agents typically requires human participants, a process that is costly and difficult to scale. LLM-based user simulators and LLM-as-a-judge evaluators offer a promising alternative, but how close they are to replacing real users remains unclear. We study this through a human user study (52 participants) and a simulated user study (four LLM-based simulators) applied to an experimental conversational sales agent, comparing LLM-as-a-judge assessments against human self-reported ratings. The results show that none of our simulators fully replicates human interaction patterns, and none of the LLM-based evaluators shows strong correlation with human ratings on real dialogues. We provide practical guidelines for combining automated and human evaluation, identifying key areas for improvement and highlighting when real-user studies remain essential.
Anthology ID:
2026.emnlp-industry.46
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
763–784
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.46/
DOI:
Bibkey:
Cite (ACL):
Justyna Gromada, Ekaterina Isakova, Joanna Brudnik, Alicja Kasicka, Natalia Krawczyk, Bartosz Przybył, Lukasz Krajewski, and Michał K. Szczerbak. 2026. From Simulation to Reality: Validating Automated Evaluation of Conversational Agents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 763–784, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
From Simulation to Reality: Validating Automated Evaluation of Conversational Agents (Gromada et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.46.pdf