Evaluating Bias in LLM-Synthetic Data across Majority and Minority Groups on General and Stigmatized Topics: The Case of Multicultural and Monocultural Adolescents in South Korea

Jiyun Beak, Myokyung Han, Lanu Kim


Abstract
Large Language Models (LLMs) are increasingly used to replicate human responses in survey data, yet it remains unclear whether they perform equally well for social minorities and majorities. Using a unique survey conducted in South Korea that provided identical questionnaires to adolescents from multicultural and monocultural families, we examine group-level differences in the accuracy of LLM-generated synthetic data. We construct personas that mirror individual-level demographic profiles and prompt two LLMs, llama3:latest and gpt-4o, to answer 77 survey questions across 11 question domains. We find marginal differences in LLM performance between minority and majority groups. Instead, replication performance varies by whether question prompts contain socially stigmatized words and by which LLM model we use. These findings highlight both the potential and the limitations of using LLMs to generate synthetic survey data targeting social minorities.
Anthology ID:
2026.nlp4pi-1.15
Volume:
Proceedings of the Fifth Workshop on NLP for Positive Impact (NLP4PI)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Katherine Atwell, Angana Borah, Daryna Dementieva, Elisa Kreiss, Neema Kotonya, Jiarui Liu, Liz Olson, Ruyuan Wan, Jieyu Zhao
Venues:
NLP4PI | WS
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
161–174
Language:
URL:
https://aclanthology.org/2026.nlp4pi-1.15/
DOI:
Bibkey:
Cite (ACL):
Jiyun Beak, Myokyung Han, and Lanu Kim. 2026. Evaluating Bias in LLM-Synthetic Data across Majority and Minority Groups on General and Stigmatized Topics: The Case of Multicultural and Monocultural Adolescents in South Korea. In Proceedings of the Fifth Workshop on NLP for Positive Impact (NLP4PI), pages 161–174, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Evaluating Bias in LLM-Synthetic Data across Majority and Minority Groups on General and Stigmatized Topics: The Case of Multicultural and Monocultural Adolescents in South Korea (Beak et al., NLP4PI 2026)
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PDF:
https://aclanthology.org/2026.nlp4pi-1.15.pdf