Inspectable Neural Markov Models for Non-Stationary Time Series
可检查的神经马尔可夫模型用于非平稳时间序列
Jan Rovirosa, Jesse Schmolze
AI总结 提出一种神经网络参数化随机矩阵流形的混合方法,用于估计稀疏数据下的非平稳马尔可夫链,以金融市场为测试平台,发现基于已实现波动率的状态变量比基于收益的状态变量更一致,并在9/10资产上降低了5.6%的Chapman-Kolmogorov差异并提高了留出似然。
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- 9 pages, 5 figures, 2 tables. Presented at The 2026 ASA Midwest Regional Conference in Statistics and Data Science
建模非平稳随机系统需要平衡深度学习的表示能力与经典概率模型的结构透明度。马尔可夫转移矩阵提供了这样一个框架,但传统的基于频率的估计在高分辨率下由于数据稀疏性而失效。我们提出了一种混合方法,通过神经网络参数化随机矩阵的流形,从而在稀疏数据情况下估计时间非齐次马尔可夫链,并以金融市场作为测试平台,研究马尔可夫状态变量作为关键归纳偏置。我们表明,基于已实现波动率的状态变量比基于收益的状态变量产生更内部一致的马尔可夫结构,在9/10资产上实现了5.6%的Chapman-Kolmogorov差异减少和优越的留出似然。与黑盒序列模型不同,我们的方法生成显式矩阵,适用于直接几何分析,揭示了诸如高波动率下转移概率的普遍同质化等结构性发现。
Modeling non-stationary stochastic systems requires balancing the representational capacity of deep learning with the structural transparency of classical probabilistic models. Markov transition matrices provide such a framework, but traditional frequency-based estimation collapses at high resolutions due to data sparsity. We propose a hybrid approach that parameterizes the manifold of stochastic matrices through a neural network, enabling estimation of time-inhomogeneous Markov chains in sparse-data regimes, and use financial markets as a testbed to investigate the Markov state variable as a critical inductive bias. We show that conditioning on realized volatility produces a more internally consistent Markovian structure than return-based states, achieving a $5.6\%$ reduction in Chapman-Kolmogorov discrepancy and superior held-out likelihood in 9 of 10 assets. Unlike black-box sequence models, our approach generates explicit matrices amenable to direct geometric analysis, surfacing structural findings such as the universal homogenization of transition probabilities under high-volatility regimes.