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rosie · 2024年04月17日

AR Model关于autocorrelation的判断

NO.PZ2023040502000045

问题如下:

Luke examines West Texas Intermediate (WTI) monthly crude oil price data, expressed in US dollars per barrel, for the 181-month period from August 2000 through August 2015.


Based on the data for the AR(1) model( the critical value is 1.97), he can conclude that the:

选项:

A.

residuals are not serially correlated.

B.

autocorrelations do not differ significantly from zero.

C.

standard error for each of the autocorrelations is 0.0745.

解释:

The standard error of the autocorrelations is calculated as , where T represents the number of observations used in the regression. Therefore, the standard error for each of the autocorrelations is = 0.0745.Martinez can conclude that the residuals are serially correlated and are significantly different from zero because two of the four autocorrelations in Exhibit 2 have a t-statistic in absolute value that is greater than the critical value of 1.97.

Choices A and B are incorrect because two of the four autocorrelations have at-statistic in absolute value that is greater than the critical value of the t-statistic of 1.97.

请问题目中的Lag3以及Lag4,t-statistic是小于1.96的,也就是不能拒绝Ho

在不能拒绝Ho的情况下,是不是表示就存在autocorrelation的现象呢? 

我记得课上说只要Lag1-4中有任何一个接受H0,就需要修正了

那么B选项中所述“autocorrelations do not differ significantly from zero.”错在哪里呢?

1 个答案
已采纳答案

品职助教_七七 · 2024年04月17日

嗨,爱思考的PZer你好:


“autocorrelations do not differ significantly from zero”的意思是所有lag的atuocorrelations都等于0。

由于检验结果是两个等于0,两个不等于0,所以这句话怎么说都是错的。

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