用模拟推断高效估计复杂时间模型参数,提升精度与可靠性。
Simulation-based inference via telescoping ratio estimation for trawl processes
- 分维逐步推导后验密度,结合切比雪夫多项式加速采样
- 在能源需求数据上实现高精度参数估计,可信区间达标
- 支持新数据直接复用,适合长序列、非马尔可夫过程研究者
大规模复杂数据的兴起推动了对能捕捉边际偏度、非高斯尾部、长记忆甚至非马尔可夫动态的时间随机过程的关注。尽管这些模型易于模拟,但参数估计仍具挑战性。模拟基础推断(SBI)提供了一条可行路径,但现有方法通常需要大量训练数据或复杂架构,且常导致置信(可信)区间未达名义水平,影响估计可靠性。为此,本文提出一种快速、准确、样本高效的SBI框架,适用于不可解析的随机过程。该方法分为两步:首先按参数维度逐步分解后验密度;其次利用切比雪夫多项式近似高效生成独立后验样本,即使在马尔可夫链蒙特卡洛混合理差时也能实现精确推断。我们还开发了新型诊断工具与事后校准技术,不仅提升推断性能,还使训练模型可直接应用于不同长度的新时间序列,实现训练成本摊销。方法在广义无穷可分的拖网过程(trawl processes)上验证,该类模型推广了单变量高斯过程,应用于能源需求数据。
原文摘要 · Abstract (English)
The growing availability of large and complex datasets has increased interest in temporal stochastic processes that can capture stylized facts such as marginal skewness, non-Gaussian tails, long memory, and even non-Markovian dynamics. While such models are often easy to simulate from, parameter estimation remains challenging. Simulation-based inference (SBI) offers a promising way forward, but existing methods typically require large training datasets or complex architectures and frequently yield confidence (credible) regions that fail to attain their nominal values, raising doubts on the reliability of estimates for the very features that motivate the use of these models. To address these challenges, we propose a fast and accurate, sample-efficient SBI framework for amortized posterior inference applicable to intractable stochastic processes. The proposed approach relies on two main steps: first, we learn the posterior density by decomposing it sequentially across parameter dimensions. Then, we use Chebyshev polynomial approximations to efficiently generate independent posterior samples, enabling accurate inference even when Markov chain Monte Carlo methods mix poorly. We further develop novel diagnostic tools for SBI in this context, as well as post-hoc calibration techniques; the latter not only lead to performance improvements of the learned inferential tool, but also to the ability to reuse it directly with new time series of varying lengths, thus amortizing the training cost. We demonstrate the method's effectiveness on trawl processes, a class of flexible infinitely divisible models that generalize univariate Gaussian processes, applied to energy demand data.
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