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wenxing · 2023年02月11日

求解析

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NO.PZ202208300200000104

问题如下:

Assuming a 5% level of significance, the most appropriate conclusion that can be drawn from the Dickey–Fuller results reported in Exhibit 2 is that the:

选项:

A.test for a unit root is inconclusive for the dependent variable.

B.dependent variable exhibits a unit root but the independent variables do not.

C.independent variables exhibit unit roots but the dependent variable does not.

解释:

The Dickey–Fuller test uses a regression of the type:xt-xt-1 =b0+g xt-1+εt

The null hypothesis is H0: g= 0 versus the alternative hypothesis H1: g< 0 (a one-tail test). If g=0 the time series has a unit root and is nonstationary. Thus, if we fail to reject the null hypothesis, we accept the possibility that the time series has a unit root and is nonstationary. Based on the t ratios and their significance levels in Exhibit 2, we reject the null hypothesis that the coefficient is zero for both outside air temperature and assembly line speed (i.e., the independent variables). We do not reject the null for the dependent variable, defective assemblies per hour.

求解析!!!,!!!!!!!!!!!!!!

1 个答案

星星_品职助教 · 2023年02月12日

同学你好,

这道题有些超纲,DF test的具体做法教材没讲也不要求掌握。但原则依然是当p-value<significance level时,拒绝原假设。(significance of t就是p-value的同义表达)。

由此可以看出,两个X的p-value都小于5%(拒绝g=0的原假设,即covariance stationary),但Y的p-value大于5%(不能拒绝原假设,不满足covariance stationary,存在unit root)。

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NO.PZ202208300200000104问题如下 Assuming a 5% level of significance, the most appropriate conclusionthcawn from the ckey–Fuller results reportein Exhibit 2 is thatthe: A.test for a unit root is inconclusive for the penntvariable.B.pennt variable exhibits a unit root but theinpennt variables not.C.inpennt variables exhibitunit roots but the pennt variable es not. The ckey–Fuller test uses a regression of the type:xt-xt-1=b0+g xt-1+εt The null hypothesis is H0: g= 0 versus the alternativehypothesis H1: g 0 (a one-tail test). If g=0 the time series hasa unit root anis nonstationary. Thus, if we fail to rejethe nullhypothesis, we accept the possibility ththe time series ha unit root ans nonstationary. Baseon the t ratios antheir significanlevels inExhibit 2, we rejethe null hypothesis ththe coefficient is zero for bothoutsi air temperature anassembly line spee(i.e., the inpenntvariables). We not rejethe null for the pennt variable, fectiveassemblies per hour. 表格中的数字怎么和题目对应起来?完全不知道怎么用

2024-05-24 07:26 1 · 回答

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2022-11-30 20:35 1 · 回答