Offline vs. Online Learning in Model-based RL: Lessons for Data Collection Strategies

Fuente: arXiv
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Hauptverfasser: Chen, Jiaqi, Shi, Ji, Sancaktar, Cansu, Frey, Jonas, Martius, Georg
Format: Preprint
Veröffentlicht: 2025
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author Chen, Jiaqi
Shi, Ji
Sancaktar, Cansu
Frey, Jonas
Martius, Georg
author_facet Chen, Jiaqi
Shi, Ji
Sancaktar, Cansu
Frey, Jonas
Martius, Georg
contents Data collection is crucial for learning robust world models in model-based reinforcement learning. The most prevalent strategies are to actively collect trajectories by interacting with the environment during online training or training on offline datasets. At first glance, the nature of learning task-agnostic environment dynamics makes world models a good candidate for effective offline training. However, the effects of online vs. offline data on world models and thus on the resulting task performance have not been thoroughly studied in the literature. In this work, we investigate both paradigms in model-based settings, conducting experiments on 31 different environments. First, we showcase that online agents outperform their offline counterparts. We identify a key challenge behind performance degradation of offline agents: encountering Out-Of-Distribution states at test time. This issue arises because, without the self-correction mechanism in online agents, offline datasets with limited state space coverage induce a mismatch between the agent's imagination and real rollouts, compromising policy training. We demonstrate that this issue can be mitigated by allowing for additional online interactions in a fixed or adaptive schedule, restoring the performance of online training with limited interaction data. We also showcase that incorporating exploration data helps mitigate the performance degradation of offline agents. Based on our insights, we recommend adding exploration data when collecting large datasets, as current efforts predominantly focus on expert data alone.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05735
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Offline vs. Online Learning in Model-based RL: Lessons for Data Collection Strategies
Chen, Jiaqi
Shi, Ji
Sancaktar, Cansu
Frey, Jonas
Martius, Georg
Machine Learning
Artificial Intelligence
Data collection is crucial for learning robust world models in model-based reinforcement learning. The most prevalent strategies are to actively collect trajectories by interacting with the environment during online training or training on offline datasets. At first glance, the nature of learning task-agnostic environment dynamics makes world models a good candidate for effective offline training. However, the effects of online vs. offline data on world models and thus on the resulting task performance have not been thoroughly studied in the literature. In this work, we investigate both paradigms in model-based settings, conducting experiments on 31 different environments. First, we showcase that online agents outperform their offline counterparts. We identify a key challenge behind performance degradation of offline agents: encountering Out-Of-Distribution states at test time. This issue arises because, without the self-correction mechanism in online agents, offline datasets with limited state space coverage induce a mismatch between the agent's imagination and real rollouts, compromising policy training. We demonstrate that this issue can be mitigated by allowing for additional online interactions in a fixed or adaptive schedule, restoring the performance of online training with limited interaction data. We also showcase that incorporating exploration data helps mitigate the performance degradation of offline agents. Based on our insights, we recommend adding exploration data when collecting large datasets, as current efforts predominantly focus on expert data alone.
title Offline vs. Online Learning in Model-based RL: Lessons for Data Collection Strategies
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2509.05735