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arXiv 2408.03024stat.MEstat.CO
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可逆 Markov 链自协方差序列的加权形状约束估计

Weighted shape-constrained estimation for the autocovariance sequence from a reversible Markov chain

Hyebin Song, Stephen Berg

AI总结:

针对可逆 Markov 链,本文提出在 Fourier 域依据周期图渐近方差加权的 ℓ2 形状约束估计方法,可强一致估计自协方差序列与谱密度,并提升 MCMC 不确定性量化效果。

摘要:

我们提出了一种新颖的加权 ℓ2 投影方法,用于估计可逆 Markov 链的自协方差序列和谱密度函数。Berg 与 Song(2023)通过将初始估计用 ℓ2 投影到形状约束空间,引入了一种用于自协方差函数的最小二乘形状约束估计方法。尽管最小二乘目标函数在形状约束回归中被广泛使用,但由于输入函数中的相关性和方差不等,它可能不是最优的。为解决这一问题,我们提出了一种加权最小二乘方法,在变换后的数据上定义加权范数。具体而言,我们将输入的自协方差序列变换到 Fourier 域,并利用周期图纵坐标的渐近独立性,基于样本周期图的渐近方差施加权重。我们的方法也可等价地视为通过对谱密度函数的 Fourier 级数施加形状约束来估计该函数。我们证明了加权方法对谱密度和自协方差序列均能产生强一致估计。实证研究表明,该方法在 Markov chain Monte Carlo 估计的不确定性量化中十分有效,优于未加权的矩 LS 估计量以及其他最先进方法。

英文摘要:

We present a novel weighted $\ell_2$ projection method for estimating autocovariance sequences and spectral density functions from reversible Markov chains. Berg and Song (2023) introduced a least-squares shape-constrained estimation approach for the autocovariance function by projecting an initial estimate onto a shape-constrained space using an $\ell_2$ projection. While the least-squares objective is commonly used in shape-constrained regression, it can be suboptimal due to correlation and unequal variances in the input function. To address this, we propose a weighted least-squares method that defines a weighted norm on transformed data. Specifically, we transform an input autocovariance sequence into the Fourier domain and apply weights based on the asymptotic variance of the sample periodogram, leveraging the asymptotic independence of periodogram ordinates. Our proposal can equivalently be viewed as estimating a spectral density function by applying shape constraints to its Fourier series. We demonstrate that our weighted approach yields strongly consistent estimates for both the spectral density and the autocovariance sequence. Empirical studies show its effectiveness in uncertainty quantification for Markov chain Monte Carlo estimation, outperforming the unweighted moment LS estimator and other state-of-the-art methods.

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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