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AI 根据所提供的论文材料归类:摘要研究通用 EM 算法的统计理论,混合回归和缺失协变量不足以确定给定经济计量细分方向。

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代码、数据与补充材料

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关注这篇论文的作者
Bin Yu

EM 算法的统计保证:从总体到有限样本分析

研究问题
如何判断 EM 迭代是否接近总体似然的指定全局最优点,而非只停在不良局部点,并量化其收敛区域和速度?
方法与思路
作者分别分析总体与有限样本下的 EM 及一阶 EM,刻画局部收敛区域,并在两类对称混合模型和完全随机缺失回归中验证。
材料陈述的贡献
摘要称建立了迭代进入指定总体最优点小邻域的理论框架,并为正确设定模型中由合适初值经 EM 精化的两阶段估计提供保证。
阅读关注点
应核对初始估计的要求、总体收敛与样本误差的衔接、邻域大小和收敛速度,以及三个例子中条件验证的具体范围。
阅读边界
仅据 OpenAlex 索引摘要,稿件版本未注明;保证依赖收敛区域与模型条件,摘要没有声称任意初始化均能达到全局最优。

原文摘要

The EM algorithm is a widely used tool in maximum-likelihood estimation in incomplete data problems. Existing theoretical work has focused on conditions under which the iterates or likelihood values converge, and the associated rates of convergence. Such guarantees do not distinguish whether the ultimate fixed point is a near global optimum or a bad local optimum of the sample likelihood, nor do they relate the obtained fixed point to the global optima of the idealized population likelihood (obtained in the limit of infinite data). This paper develops a theoretical framework for quantifying when and how quickly EM-type iterates converge to a small neighborhood of a given global optimum of the population likelihood. For correctly specified models, such a characterization yields rigorous guarantees on the performance of certain two-stage estimators in which a suitable initial pilot estimator is refined with iterations of the EM algorithm. Our analysis is divided into two parts: a treatment of the EM and first-order EM algorithms at the population level, followed by results that apply to these algorithms on a finite set of samples. Our conditions allow for a characterization of the region of convergence of EM-type iterates to a given population fixed point, that is, the region of the parameter space over which convergence is guaranteed to a point within a small neighborhood of the specified population fixed point. We verify our conditions and give tight characterizations of the region of convergence for three canonical problems of interest: symmetric mixture of two Gaussians, symmetric mixture of two regressions and linear regression with covariates missing completely at random.

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