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arXiv math/0602326math.STstat.TH
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自回归过程中同实现预测的阶数选择

Order selection for same-realization predictions in autoregressive processes

Ching-Kang Ing, Ching-Zong Wei

摘要:

假设观测值是由无限阶自回归[AR($\infty$)]过程生成的。Shibata [Ann Statistist. 8(1980)147- 164]考虑了选择有限阶AR模型的问题,为了获得更好的近似,允许阶数随着观测数的增加而变得无限。他证明,为了预测独立复制的未来,赤池信息准则(AIC)及其变体是渐近有效的。虽然柴田的渐近效率的概念已被广泛接受的文献中,它不是一个自然属性的时间序列分析。这是因为当时间序列的新观测值可用时,它们并不独立于先前的数据。为了克服这个困难,在本文中,我们专注于顺序选择预测的未来观察到的时间序列,被称为相同的实现预测。我们提出了第一个理论验证,AIC及其变体仍然是渐近有效的(在第4节定义的意义上)相同的实现预测。为了得到这一结果,一个技术条件,容易满足在一般实践中,简化复杂的依赖结构之间的选定的订单,估计参数和未来的观测。此外,进行了模拟研究,以说明AIC的实际意义。这项研究表明,AIC也产生了令人满意的相同的实现预测在有限的样本。另一方面,指出了AIC在相同实现环境下的局限性。值得注意的是,AIC的这种限制对于相应的独立情况并不存在。

英文摘要:

Assume that observations are generated from an infinite-order autoregressive [AR($\infty$)] process. Shibata [Ann. Statist. 8 (1980) 147--164] considered the problem of choosing a finite-order AR model, allowing the order to become infinite as the number of observations does in order to obtain a better approximation. He showed that, for the purpose of predicting the future of an independent replicate, Akaike's information criterion (AIC) and its variants are asymptotically efficient. Although Shibata's concept of asymptotic efficiency has been widely accepted in the literature, it is not a natural property for time series analysis. This is because when new observations of a time series become available, they are not independent of the previous data. To overcome this difficulty, in this paper we focus on order selection for forecasting the future of an observed time series, referred to as same-realization prediction. We present the first theoretical verification that AIC and its variants are still asymptotically efficient (in the sense defined in Section 4) for same-realization predictions. To obtain this result, a technical condition, easily met in common practice, is introduced to simplify the complicated dependent structures among the selected orders, estimated parameters and future observations. In addition, a simulation study is conducted to illustrate the practical implications of AIC. This study shows that AIC also yields a satisfactory same-realization prediction in finite samples. On the other hand, a limitation of AIC in same-realization settings is pointed out. It is interesting to note that this limitation of AIC does not exist for corresponding independent cases.

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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