Is Your Imitation Learning Policy Better than Mine? Policy Comparison with Near-Optimal Stopping

Fuente: arXiv
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Main Authors: Snyder, David, Hancock, Asher James, Badithela, Apurva, Dixon, Emma, Miller, Patrick, Ambrus, Rares Andrei, Majumdar, Anirudha, Itkina, Masha, Nishimura, Haruki
Format: Preprint
Published: 2025
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author Snyder, David
Hancock, Asher James
Badithela, Apurva
Dixon, Emma
Miller, Patrick
Ambrus, Rares Andrei
Majumdar, Anirudha
Itkina, Masha
Nishimura, Haruki
author_facet Snyder, David
Hancock, Asher James
Badithela, Apurva
Dixon, Emma
Miller, Patrick
Ambrus, Rares Andrei
Majumdar, Anirudha
Itkina, Masha
Nishimura, Haruki
contents Imitation learning has enabled robots to perform complex, long-horizon tasks in challenging dexterous manipulation settings. As new methods are developed, they must be rigorously evaluated and compared against corresponding baselines through repeated evaluation trials. However, policy comparison is fundamentally constrained by a small feasible sample size (e.g., 10 or 50) due to significant human effort and limited inference throughput of policies. This paper proposes a novel statistical framework for rigorously comparing two policies in the small sample size regime. Prior work in statistical policy comparison relies on batch testing, which requires a fixed, pre-determined number of trials and lacks flexibility in adapting the sample size to the observed evaluation data. Furthermore, extending the test with additional trials risks inducing inadvertent p-hacking, undermining statistical assurances. In contrast, our proposed statistical test is sequential, allowing researchers to decide whether or not to run more trials based on intermediate results. This adaptively tailors the number of trials to the difficulty of the underlying comparison, saving significant time and effort without sacrificing probabilistic correctness. Extensive numerical simulation and real-world robot manipulation experiments show that our test achieves near-optimal stopping, letting researchers stop evaluation and make a decision in a near-minimal number of trials. Specifically, it reduces the number of evaluation trials by up to 32% as compared to state-of-the-art baselines, while preserving the probabilistic correctness and statistical power of the comparison. Moreover, our method is strongest in the most challenging comparison instances (requiring the most evaluation trials); in a multi-task comparison scenario, we save the evaluator more than 160 simulation rollouts.
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id arxiv_https___arxiv_org_abs_2503_10966
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Is Your Imitation Learning Policy Better than Mine? Policy Comparison with Near-Optimal Stopping
Snyder, David
Hancock, Asher James
Badithela, Apurva
Dixon, Emma
Miller, Patrick
Ambrus, Rares Andrei
Majumdar, Anirudha
Itkina, Masha
Nishimura, Haruki
Robotics
Machine Learning
Imitation learning has enabled robots to perform complex, long-horizon tasks in challenging dexterous manipulation settings. As new methods are developed, they must be rigorously evaluated and compared against corresponding baselines through repeated evaluation trials. However, policy comparison is fundamentally constrained by a small feasible sample size (e.g., 10 or 50) due to significant human effort and limited inference throughput of policies. This paper proposes a novel statistical framework for rigorously comparing two policies in the small sample size regime. Prior work in statistical policy comparison relies on batch testing, which requires a fixed, pre-determined number of trials and lacks flexibility in adapting the sample size to the observed evaluation data. Furthermore, extending the test with additional trials risks inducing inadvertent p-hacking, undermining statistical assurances. In contrast, our proposed statistical test is sequential, allowing researchers to decide whether or not to run more trials based on intermediate results. This adaptively tailors the number of trials to the difficulty of the underlying comparison, saving significant time and effort without sacrificing probabilistic correctness. Extensive numerical simulation and real-world robot manipulation experiments show that our test achieves near-optimal stopping, letting researchers stop evaluation and make a decision in a near-minimal number of trials. Specifically, it reduces the number of evaluation trials by up to 32% as compared to state-of-the-art baselines, while preserving the probabilistic correctness and statistical power of the comparison. Moreover, our method is strongest in the most challenging comparison instances (requiring the most evaluation trials); in a multi-task comparison scenario, we save the evaluator more than 160 simulation rollouts.
title Is Your Imitation Learning Policy Better than Mine? Policy Comparison with Near-Optimal Stopping
topic Robotics
Machine Learning
url https://arxiv.org/abs/2503.10966