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arXiv 1208.4989stat.MEstat.AP
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状态特定图模型下高维隐马尔可夫模型的惩罚估计

Penalized estimation in high-dimensional hidden Markov models with state-specific graphical models

Nicolas Städler, Sach Mukherjee

摘要:

本文研究了具有多元正态观测的隐马尔可夫模型的惩罚估计。在中到大的维度设置中,由于状态的隐藏性质所引起的几个问题,在实践中对HALCOST的估计仍然具有挑战性。我们解决这些问题的$\ell_1$ -惩罚状态特定的逆协方差阵。惩罚估计导致稀疏的逆协方差阵,它可以被解释为状态特定的条件独立图。惩罚是不平凡的,在这个潜在的变量设置,我们提出了一个惩罚,自动适应的状态数$K$和状态特定的样本量,并可以应付未知状态所产生的缩放问题。该方法是自适应的和非常普遍的,特别适用于低维和高维的设置,而不需要手动调整。此外,我们的方法有利于探索的状态数$K$通过耦合估计连续的候选值$K$。仿真实验结果表明了该方法的有效性。在基因组生物学的一个具有挑战性的真实数据示例中,我们展示了我们的方法在预测能力方面的收益,并提供比现有方法更丰富的估计。

英文摘要:

We consider penalized estimation in hidden Markov models (HMMs) with multivariate Normal observations. In the moderate-to-large dimensional setting, estimation for HMMs remains challenging in practice, due to several concerns arising from the hidden nature of the states. We address these concerns by $\ell_1$-penalization of state-specific inverse covariance matrices. Penalized estimation leads to sparse inverse covariance matrices which can be interpreted as state-specific conditional independence graphs. Penalization is nontrivial in this latent variable setting; we propose a penalty that automatically adapts to the number of states $K$ and the state-specific sample sizes and can cope with scaling issues arising from the unknown states. The methodology is adaptive and very general, applying in particular to both low- and high-dimensional settings without requiring hand tuning. Furthermore, our approach facilitates exploration of the number of states $K$ by coupling estimation for successive candidate values $K$. Empirical results on simulated examples demonstrate the effectiveness of the proposed approach. In a challenging real data example from genome biology, we demonstrate the ability of our approach to yield gains in predictive power and to deliver richer estimates than existing methods.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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