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arXiv 1111.5948stat.ML
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关于l_1均值和方差滤波

On l_1 Mean and Variance Filtering

Bo Wahlberg, Cristian R. Rojas, Mariette Annergren

摘要:

本文讨论的问题分割的时间序列的变化,在均值或方差。第一种情况是将时间数据建模为一系列独立的正态分布随机变量,这些变量具有未知的、可能变化的平均值,但方差是固定的。主要的假设是,平均值是分段恒定的时间,任务是估计的变化时间和段内的平均值。第二种情况是均值恒定,但方差可以变化。假设方差在时间上是分段恒定的,我们希望估计变化时间和分段内的方差值。为了解决这些问题,我们将研究l_1正则化极大似然方法,与融合套索方法和l_1趋势滤波相关,其中待估计的参数在每个样本处自由变化。为了惩罚估计参数的变化,参数的时间差的l_1范数被用作正则化项。这个想法与全变分去噪密切相关。主要的贡献是,这个方差估计问题的凸公式,其中参数化是基于方差的逆,可以制定为一定的l_1均值估计问题。这意味着均值估计的结果和方法可以应用于方差分割/估计的挑战性问题。

英文摘要:

This paper addresses the problem of segmenting a time-series with respect to changes in the mean value or in the variance. The first case is when the time data is modeled as a sequence of independent and normal distributed random variables with unknown, possibly changing, mean value but fixed variance. The main assumption is that the mean value is piecewise constant in time, and the task is to estimate the change times and the mean values within the segments. The second case is when the mean value is constant, but the variance can change. The assumption is that the variance is piecewise constant in time, and we want to estimate change times and the variance values within the segments. To find solutions to these problems, we will study an l_1 regularized maximum likelihood method, related to the fused lasso method and l_1 trend filtering, where the parameters to be estimated are free to vary at each sample. To penalize variations in the estimated parameters, the l_1-norm of the time difference of the parameters is used as a regularization term. This idea is closely related to total variation denoising. The main contribution is that a convex formulation of this variance estimation problem, where the parametrization is based on the inverse of the variance, can be formulated as a certain l_1 mean estimation problem. This implies that results and methods for mean estimation can be applied to the challenging problem of variance segmentation/estimation.

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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