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AI-Assisted Variance Reduction in Randomized Experiments

David Arbour, Eli Ben-Michael, Avi Feller, Apoorva Lal, Lo-Hua Yuan

arXiv 7 Jun 2026 · Econometrics

arXiv:2606.08853 · PDF · DOI · OpenAlex · Extracted main text

Abstract

Generative AI and large language models can produce realistic predictions of human behavior from rich, unstructured inputs with little to no task-specific training data. Recent work uses these “digital twin” predictions to supplement human responses in surveys and experiments. We study the special case of using AI-generated predictions to reduce variance in randomized experiments. We argue that doing so requires no new estimators and that researchers can simply include AI predictions as covariates in standard regression adjustment, analogous to adjusting for a prognostic score. A benefit of this approach is a “do no harm” property whereby the adjusted estimator reverts to the unadjusted difference in means when predictions are uninformative. Other methods, such as variants of prediction-powered inference, do not have this guarantee. We provide implementation guidance, including how to obtain continuous scores from discrete LLM outputs and how to use LLMs to featurize unstructured inputs as auxiliary covariates. We demonstrate these ideas in simulations and three empirical applications: a survey mega-study, an email marketing A/B test, and a large-scale technology platform experiment. Overall, efficiency gains are real if modest, with greater benefits in studies that contain substantial text and other unstructured data. We also confirm the do no harm property empirically. Given these gains and limited costs, we recommend adjusting for AI-generated predictions as a regular empirical practice.

Citation extraction

46
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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Winston Lin (2013) Agnostic notes on regression adjustments to experimental data: Reexamining Freedman's critique1.00073100%
2Naoki Egami, Musashi Hinck, Brandon Stewart, and Hanying Wei (2023) Using imperfect surrogates for downstream inference: Design-based supervised learning for social science applications of large l…1.00065100%
3Alex Deng, Luke Hagar, Nathaniel Stevens, Tatiana Xifara, Lo-Hua Yua… (2023) From augmentation to decomposition: A new look at CUPED in 2023 self1.00053100%
4Tianyi Peng, George Gui, Melanie Brucks, Daniel J Merlau, Grace Jiar… (2025) Digital twins as funhouse mirrors: Five key distortions1.00053100%
5Xinrui Ruan, Xinwei Ma, Yingfei Wang, Waverly Wei, and Jingshen Wang (2025) Can language models boost the power of randomized experiments without statistical bias?1.00053100%
6Peng Ding (2024) A first course in causal inference0.87462100%
7Anastasios N Angelopoulos, Stephen Bates, Clara Fannjiang, Michael I… (2023) Prediction-powered inference0.87452100%
8Piersilvio De Bartolomeis, Javier Abad, Guanbo Wang, Konstantin Donh… (2025) Efficient Randomized Experiments Using Foundation Models, February 20250.84333100%
9Chris Engh and P. M. Aronow (2025) Using LLMs to directly guess conditional expectations can improve efficiency in causal estimation0.84333100%
10Lisa P Argyle, Ethan C Busby, Nancy Fulda, Joshua R Gubler, Christop… (2023) Out of one, many: Using language models to simulate human samples0.73732100%

Showing the top 10 of 46 scored citations.