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arXiv 1004.2138math.STstat.MEstat.TH
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高维时间序列潜因子模型的估计

Estimation for Latent Factor Models for High-Dimensional Time Series

Clifford Lam, Qiwei Yao, Neil Bathia

摘要:

研究了基于公共因子的高维时间序列降维问题。特别地,我们允许时间序列$p$的维度与样本大小$n$一样大,甚至更大。通过对$p\times p$非负定矩阵的特征分析,对因子载荷矩阵和因子过程本身进行估计。我们发现,当所有的因素是强的意义上说,在因子加载矩阵中的每一列的范数是$p^{1/2}$的顺序,估计因子加载矩阵,以及由此产生的估计精度矩阵的原始$p$ -变体时间序列,弱一致的$L_2$ -范数与独立的$p$的收敛速度。这个结果清楚地表明,在维度上,“诅咒”被“祝福”所抵消。我们还建立了估计的渐近性质时,并非所有的因素都是强的。对于后一种情况,一个两步估计程序是优选的,因此渐近理论。所提出的方法连同其渐近性质进一步说明了在模拟研究。一个实际的数据集的应用程序也报告。

英文摘要:

This paper deals with the dimension reduction for high-dimensional time series based on common factors. In particular we allow the dimension of time series $p$ to be as large as, or even larger than, the sample size $n$. The estimation for the factor loading matrix and the factor process itself is carried out via an eigenanalysis for a $p\times p$ non-negative definite matrix. We show that when all the factors are strong in the sense that the norm of each column in the factor loading matrix is of the order $p^{1/2}$, the estimator for the factor loading matrix, as well as the resulting estimator for the precision matrix of the original $p$-variant time series, are weakly consistent in $L_2$-norm with the convergence rates independent of $p$. This result exhibits clearly that the `curse' is canceled out by the `blessings' in dimensionality. We also establish the asymptotic properties of the estimation when not all factors are strong. For the latter case, a two-step estimation procedure is preferred accordingly to the asymptotic theory. The proposed methods together with their asymptotic properties are further illustrated in a simulation study. An application to a real data set is also reported.

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