Breaking the Winner's Curse with Bayesian Hybrid Shrinkage

Fuente: arXiv
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Auteurs principaux: Mudd, Richard, Zaidi, Abbas, Friedberg, Rina, Gorbachev, Ilya, Choubey, Anchal, Nassif, Houssam
Format: Preprint
Publié: 2026
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author Mudd, Richard
Zaidi, Abbas
Friedberg, Rina
Gorbachev, Ilya
Choubey, Anchal
Nassif, Houssam
author_facet Mudd, Richard
Zaidi, Abbas
Friedberg, Rina
Gorbachev, Ilya
Choubey, Anchal
Nassif, Houssam
contents The widespread adoption of randomized controlled trials (A/B Tests) for decision-making has introduced a pervasive "Winner's Curse": experiments selected for launch often exhibit upwardly biased effect estimates and invalid confidence intervals. This selection bias leads to over-optimistic impact projections and undermines decision-making, particularly in low-power regimes. We propose Bayesian Hybrid Shrinkage (BHS), an empirical Bayes (EB) framework that leverages data-driven priors to mitigate selection bias and provides accurate uncertainty quantification. Unlike traditional EB methods that apply uniform shrinkage, BHS introduces an experiment-specific "local" shrinkage factor that incorporates individual experiment characteristics, improving robustness against prior misspecification. We also derive a closed-form inference strategy designed for high-throughput production environments. Extensive simulations and real-world evaluations at Meta Platforms demonstrate that BHS outperforms existing methods in terms of bias reduction and interval coverage, even under substantial violations of modeling assumptions.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12867
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Breaking the Winner's Curse with Bayesian Hybrid Shrinkage
Mudd, Richard
Zaidi, Abbas
Friedberg, Rina
Gorbachev, Ilya
Choubey, Anchal
Nassif, Houssam
Methodology
The widespread adoption of randomized controlled trials (A/B Tests) for decision-making has introduced a pervasive "Winner's Curse": experiments selected for launch often exhibit upwardly biased effect estimates and invalid confidence intervals. This selection bias leads to over-optimistic impact projections and undermines decision-making, particularly in low-power regimes. We propose Bayesian Hybrid Shrinkage (BHS), an empirical Bayes (EB) framework that leverages data-driven priors to mitigate selection bias and provides accurate uncertainty quantification. Unlike traditional EB methods that apply uniform shrinkage, BHS introduces an experiment-specific "local" shrinkage factor that incorporates individual experiment characteristics, improving robustness against prior misspecification. We also derive a closed-form inference strategy designed for high-throughput production environments. Extensive simulations and real-world evaluations at Meta Platforms demonstrate that BHS outperforms existing methods in terms of bias reduction and interval coverage, even under substantial violations of modeling assumptions.
title Breaking the Winner's Curse with Bayesian Hybrid Shrinkage
topic Methodology
url https://arxiv.org/abs/2603.12867