@inproceedings{fan-etal-2026-fairsynth,
title = "{F}air{S}ynth: Instrument-Relative Evaluation and Calibration of {LLM} Survey Simulations for Measurement Fairness",
author = "Fan, Guangrui and
Liu, DanDan and
Guo, Qian and
Niu, Xueying and
Pan, Lihu",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {EMNLP} 2026",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-emnlp.714/",
doi = "10.18653/2026.findings-emnlp.714",
pages = "14992--15012",
ISBN = "979-8-89176-462-0",
abstract = "Large language models (LLMs) are increasingly used as virtual survey respondents, yet most evaluations compare only item-level marginal response distributions. Such evaluations can miss two failures central to computational social science: synthetic respondents may distort correlations among attitudes, and errors may be distributed unevenly across countries or demographic groups. We introduce FairSynth, an instrument-relative framework for auditing and calibrating closed-ended, answer-only LLM survey simulations against existing anchor surveys. FairSynth evaluates marginal fidelity, Structural Attitude Fidelity (item{--}item correlation similarity), group representation error, distributional flattening, and between-group sign reversals. It then applies a model-agnostic post-hoc logit-shift layer with shared group parameters to reduce disparities in representation error while preserving attitude structure. Experiments on World Values Survey Wave 7 and General Social Survey 2022 show that FairSynth reduces worst-group representation error and sign reversals while improving structural fidelity on the evaluated questionnaires. FairSynth is not a substitute for human surveys; it is a measurement-fairness toolkit for auditing, stress-testing, and calibrating synthetic survey simulations when anchor data are available."
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<abstract>Large language models (LLMs) are increasingly used as virtual survey respondents, yet most evaluations compare only item-level marginal response distributions. Such evaluations can miss two failures central to computational social science: synthetic respondents may distort correlations among attitudes, and errors may be distributed unevenly across countries or demographic groups. We introduce FairSynth, an instrument-relative framework for auditing and calibrating closed-ended, answer-only LLM survey simulations against existing anchor surveys. FairSynth evaluates marginal fidelity, Structural Attitude Fidelity (item–item correlation similarity), group representation error, distributional flattening, and between-group sign reversals. It then applies a model-agnostic post-hoc logit-shift layer with shared group parameters to reduce disparities in representation error while preserving attitude structure. Experiments on World Values Survey Wave 7 and General Social Survey 2022 show that FairSynth reduces worst-group representation error and sign reversals while improving structural fidelity on the evaluated questionnaires. FairSynth is not a substitute for human surveys; it is a measurement-fairness toolkit for auditing, stress-testing, and calibrating synthetic survey simulations when anchor data are available.</abstract>
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%0 Conference Proceedings
%T FairSynth: Instrument-Relative Evaluation and Calibration of LLM Survey Simulations for Measurement Fairness
%A Fan, Guangrui
%A Liu, DanDan
%A Guo, Qian
%A Niu, Xueying
%A Pan, Lihu
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Findings of the Association for Computational Linguistics: EMNLP 2026
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-462-0
%F fan-etal-2026-fairsynth
%X Large language models (LLMs) are increasingly used as virtual survey respondents, yet most evaluations compare only item-level marginal response distributions. Such evaluations can miss two failures central to computational social science: synthetic respondents may distort correlations among attitudes, and errors may be distributed unevenly across countries or demographic groups. We introduce FairSynth, an instrument-relative framework for auditing and calibrating closed-ended, answer-only LLM survey simulations against existing anchor surveys. FairSynth evaluates marginal fidelity, Structural Attitude Fidelity (item–item correlation similarity), group representation error, distributional flattening, and between-group sign reversals. It then applies a model-agnostic post-hoc logit-shift layer with shared group parameters to reduce disparities in representation error while preserving attitude structure. Experiments on World Values Survey Wave 7 and General Social Survey 2022 show that FairSynth reduces worst-group representation error and sign reversals while improving structural fidelity on the evaluated questionnaires. FairSynth is not a substitute for human surveys; it is a measurement-fairness toolkit for auditing, stress-testing, and calibrating synthetic survey simulations when anchor data are available.
%R 10.18653/2026.findings-emnlp.714
%U https://aclanthology.org/2026.findings-emnlp.714/
%U https://doi.org/10.18653/2026.findings-emnlp.714
%P 14992-15012
Markdown (Informal)
[FairSynth: Instrument-Relative Evaluation and Calibration of LLM Survey Simulations for Measurement Fairness](https://aclanthology.org/2026.findings-emnlp.714/) (Fan et al., Findings 2026)
ACL