Elicitation Matters: How Prompts and Query Protocols Shape LLM Surrogates under Sparse Observations

Fuente: arXiv
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Auteurs principaux: Lei, Ge, Cooper, Samuel J.
Format: Preprint
Publié: 2026
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author Lei, Ge
Cooper, Samuel J.
author_facet Lei, Ge
Cooper, Samuel J.
contents Large language models are increasingly used as surrogate models for low-data optimization, but their optimizer-facing prediction and its uncertainty remain poorly understood. We study the surrogate belief elicited from an LLM under sparse observations, showing that it depends strongly on prompt text and query protocol. We introduce an uncertainty-alignment criterion that measures whether model uncertainty tracks residual ambiguity among sample-consistent functions. Across controlled inference tasks and Bayesian optimization studies, we find that structural prompts act as effective priors, POINTWISE and JOINT querying induce different beliefs, and sequential evidence leads to non-monotonic, order-sensitive confidence updates. These effects change downstream acquisition decisions and regret, showing that elicitation protocol is part of the LLM surrogate specification, not a formatting detail.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04764
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Elicitation Matters: How Prompts and Query Protocols Shape LLM Surrogates under Sparse Observations
Lei, Ge
Cooper, Samuel J.
Computation and Language
Large language models are increasingly used as surrogate models for low-data optimization, but their optimizer-facing prediction and its uncertainty remain poorly understood. We study the surrogate belief elicited from an LLM under sparse observations, showing that it depends strongly on prompt text and query protocol. We introduce an uncertainty-alignment criterion that measures whether model uncertainty tracks residual ambiguity among sample-consistent functions. Across controlled inference tasks and Bayesian optimization studies, we find that structural prompts act as effective priors, POINTWISE and JOINT querying induce different beliefs, and sequential evidence leads to non-monotonic, order-sensitive confidence updates. These effects change downstream acquisition decisions and regret, showing that elicitation protocol is part of the LLM surrogate specification, not a formatting detail.
title Elicitation Matters: How Prompts and Query Protocols Shape LLM Surrogates under Sparse Observations
topic Computation and Language
url https://arxiv.org/abs/2605.04764