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arXiv 1706.07899math.STstat.APstat.MEstat.TH
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相依数据的高维线性回归及其在临近预报中的应用

High-dimensional Linear Regression for Dependent Data with Applications to Nowcasting

Yuefeng Han, Ruey S. Tsay

摘要:

最近的研究集中在高维线性回归的$\ell_1$惩罚最小二乘(Lasso)估计,其中协变量$p$的数量远远大于样本量$n$。然而,很少有研究探讨的性质时,误差和/或协变量是序列依赖的估计。在这项研究中,我们调查的Lasso估计的理论性质的线性回归与随机设计和弱稀疏性下的系列相关和/或nonsubGaussian误差和协变量。在传统的情况下,其中的错误是独立和同分布的,并有有限的指数矩,我们表明,$p$可以在最多的权力$n$,如果错误只有有限的多项式矩。此外,由于误差和协变量的序列相关性,收敛的收敛速率变慢。我们还考虑了使用Lasso估计的模型选择的符号一致性,当误差或协变量或两者都存在序列相关性时。采用函数相关测度的框架,我们描述了如何收敛速度和选择一致性的估计依赖于依赖措施和矩条件的误差和协变量。仿真结果表明,在不相关变量的存在下,Lasso回归可以比混合频率数据采样回归(MIDAS)和Dantzig选择器更强大。我们将Lasso方法得到的结果应用于混合频率数据的临近预报,其中序列相关误差和协变量的大量是常见的。实证结果表明,Lasso程序优于MIDAS回归和自回归模型与外生变量的预测和临近预报。

英文摘要:

Recent research has focused on $\ell_1$ penalized least squares (Lasso) estimators for high-dimensional linear regressions in which the number of covariates $p$ is considerably larger than the sample size $n$. However, few studies have examined the properties of the estimators when the errors and/or the covariates are serially dependent. In this study, we investigate the theoretical properties of the Lasso estimator for a linear regression with a random design and weak sparsity under serially dependent and/or nonsubGaussian errors and covariates. In contrast to the traditional case, in which the errors are independent and identically distributed and have finite exponential moments, we show that $p$ can be at most a power of $n$ if the errors have only finite polynomial moments. In addition, the rate of convergence becomes slower owing to the serial dependence in the errors and the covariates. We also consider the sign consistency of the model selection using the Lasso estimator when there are serial correlations in the errors or the covariates, or both. Adopting the framework of a functional dependence measure, we describe how the rates of convergence and the selection consistency of the estimators depend on the dependence measures and moment conditions of the errors and the covariates. Simulation results show that a Lasso regression can be significantly more powerful than a mixed-frequency data sampling regression (MIDAS) and a Dantzig selector in the presence of irrelevant variables. We apply the results obtained for the Lasso method to nowcasting with mixed-frequency data, in which serially correlated errors and a large number of covariates are common. The empirical results show that the Lasso procedure outperforms the MIDAS regression and the autoregressive model with exogenous variables in terms of both forecasting and nowcasting.

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