Calibrating agent-based models (ABMs) in economics and finance typically involves a derivative-free search in a very large parameter space. In this work, we benchmark a number of search methods in the calibration of a well-known macroeconomic ABM on real data, and further assess the performance of "mixed strategies" made by combining different methods. We find that methods based on random-forest surrogates are particularly efficient, and that combining search methods generally increases performance since the biases of any single method are mitigated. Moving from these observations, we propose a reinforcement learning (RL) scheme to automatically select and combine search methods on-the-fly during a calibration run. The RL agent keeps exploiting a specific method only as long as this keeps performing well, but explores new strategies when the specific method reaches a performance plateau. The resulting RL search scheme outperforms any other method or method combination tested, and does not rely on any prior information or trial and error procedure.
翻译:校准经济与金融领域的基于智能体模型(ABMs)通常涉及在超大参数空间中进行无导数搜索。本研究针对一个著名的宏观经济ABM,基于真实数据对多种搜索方法进行了基准测试,并进一步评估了由不同方法组合而成的"混合策略"的性能。研究发现,基于随机森林代理的方法效率尤为突出,且组合搜索方法通常能提升性能,因为单一方法的偏差得到了缓解。基于这些观察,我们提出了一种强化学习(RL)方案,用于在校准过程中动态自动选择并组合搜索方法。该RL智能体仅在特定方法持续表现良好时持续利用该方法,而当该方法达到性能平台期时,则会探索新策略。由此产生的RL搜索方案优于测试中的任何其他方法或方法组合,且不依赖任何先验信息或试错过程。