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arXiv 0809.0064math.STstat.TH
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惩罚M-估计中正则化路径的Weak convergence

Weak convergence of the regularization path in penalized M-estimation

Jean-François Germain, François Roueff

摘要:

我们考虑的估计$\hbbeta_n(t)$定义为元素$\bphi\in\bPhi$最小化的对比度过程$\pencontrast(\bphi, t)$为每个t。我们给出了有界函数空间中$\sqrt{n}(\hbbeta_n-\bbeta)$弱收敛的一般性结果,其中对于每个t,$\bbeta(t)$是使$\pencontrast(\bphi, t)$的极限最小化的$\bphi\in\bPhi$为$n\to\infty$ .这些结果适用于惩罚M-估计的上下文中,也就是说,当$\pencontrast(\bphi, t)=M_n(\bphi)+ t J_n(\bphi)$,其中$M_n$是一个常见的对比度过程和$J_n$的惩罚,如$\ell^1$规范或平方$\ell^2$规范。函数$\hbbeta_n$则称为\emph{regularization path}。例如,我们证明了Knight和Fu(2000)中为lasso估计量建立的中心极限定理对于正则化路径在函数意义下仍然成立。其他例子包括$M_n$的各种可能的对比过程,如Pollard(1985)中考虑的那些。

英文摘要:

We consider an estimator $\hbbeta_n(t)$ defined as the element $\bphi\in\bPhi$ minimizing a contrast process $\pencontrast(\bphi, t)$ for each t. We give some general results for deriving the weak convergence of $\sqrt{n}(\hbbeta_n-\bbeta)$ in the space of bounded functions, where, for each t, $\bbeta(t)$ is the $\bphi\in\bPhi$ minimizing the limit of $\pencontrast(\bphi, t)$ as $n\to\infty$. These results are applied in the context of penalized M-estimation, that is, when $\pencontrast(\bphi, t)=M_n(\bphi)+ t J_n(\bphi)$, where $M_n$ is a usual contrast process and $J_n$ a penalty such as the $\ell^1$ norm or the squared $\ell^2$ norm. The function $\hbbeta_n$ is then called a \emph{regularization path}. For instance we show that the central limit theorem established for the lasso estimator in Knight and Fu (2000) continues to hold in a functional sense for the regularization path. Other examples include various possible contrast processes for $M_n$ such as those considered in Pollard (1985).

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