arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.04168stat.ME
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通过自适应过度差分对可能非平稳过程进行似然推断

Likelihood Inference for Possibly Non-Stationary Processes via Adaptive Overdifferencing

Maryclare Griffin, Gennady Samorodnitsky, David S. Matteson

AI总结:

针对非平稳 ARFIMA 模型似然推断难题,本文利用过度差分将其转化为平稳模型序列,并提出自适应选择上界 \ar d 的程序。

摘要:

我们观察到一种现象,通过允许记忆参数 d 的上界 \ar d 超过 0.5,可在不要求平稳性的情况下,对常用 ARFIMA 模型的参数进行精确的基于似然的推断:估计单个非平稳 ARFIMA 模型的参数,等价于估计一系列平稳 ARFIMA 模型的参数。这使得我们能够利用现有方法来计算可逆且平稳的 ARFIMA 模型的似然。由于许多标准方法在估计值接近参数空间边界时表现不佳,该方法能够改进推断。它还使我们能够利用为估计平稳过程参数而提出的大量似然近似方法。我们探讨了记忆参数 d 的估计如何依赖于上界 \ar d,并介绍了用于选择 \ar d 的自适应程序。我们通过模拟表明,当真实值高达 2.5 时,相对于现有替代方法,我们的自适应程序能够很好地估计记忆参数。

英文摘要:

We make an observation that facilitates exact likelihood-based inference for the parameters of the popular ARFIMA model without requiring stationarity by allowing the upper bound $\bar{d}$ for the memory parameter $d$ to exceed $0.5$: estimating the parameters of a single non-stationary ARFIMA model is equivalent to estimating the parameters of a sequence of stationary ARFIMA models. This allows for the use of existing methods for evaluating the likelihood for an invertible and stationary ARFIMA model. This enables improved inference because many standard methods perform poorly when estimates are close to the boundary of the parameter space. It also allows us to leverage the wealth of likelihood approximations that have been introduced for estimating the parameters of a stationary process. We explore how estimation of the memory parameter $d$ depends on the upper bound $\bar{d}$ and introduce adaptive procedures for choosing $\bar{d}$. We show via simulation how our adaptive procedures estimate the memory parameter well, relative to existing alternatives, when the true value is as large as 2.5.

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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