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Pina · 2020年02月03日

问一道题:NO.PZ201709270100000506

* 问题详情,请 查看题干

问题如下:

6. Based on the regression output in Exhibit 3 and sales data in Exhibit 4, the forecasted value of quarterly sales for March 2016 for PoweredUP is closest to:

选项:

A.

$4.193 billion.

B.

$4.205 billion.

C.

$4.231 billion.

解释:

C is correct. The quarterly sales for March 2016 is calculated as follows:

beginarraylln Salest-ln Salest-1=b0+b1(ln Salest-1-ln Salest-2)+b2(ln Salest4-ln Salest-5)ln Salestln3.868=0.00920.1279(ln3.868ln3.780)+0.7239(ln3.836ln3.418)ln Salest=1.44251Salest=e1.44251=4.231begin{array}{l}\ln{\text{ Sales}}_\text{t}{\text{-ln Sales}}_\text{t-1}{\text{=b}}_\text{0}{\text{+b}}_\text{1}{\text{(ln Sales}}_\text{t-1}{\text{-ln Sales}}_\text{t-2}{\text{)+b}}_\text{2}\text{(ln Sales}_{t-4}^{}{\text{-ln Sales}}_\text{t-5}\text{)}\\\ln{\text{ Sales}}_\text{t}-\ln3.868=0.0092-0.1279(\ln3.868-\ln3.780)+0.7239(\ln3.836-\ln3.418)\\\ln{\text{ Sales}}_\text{t}=1.44251\\{\text{Sales}}_\text{t}=e^{1.44251}=4.231

老师好 这题 为啥b0, b1可以用0.0092 and -0.1279? 不是b0's t-statistic of 1.0582 t critical value of -2.03, 不拒绝原假设 b0, b1 = 0说明b0 , b1 都应该等于0 的?

2 个答案

星星_品职助教 · 2020年05月31日

@中把中

对的,考点要区分开,考察predict Y的考点不需要考虑假设检验,假设检验是另外的考点。

星星_品职助教 · 2020年02月04日

同学你好,

这道题是考察用数据回归出来的模型预测Y。只要有数据,就能回归出模型,同时也就能预测出一个Y。

但是预测出来的Y不一定准确,因为系数可能不准确,所以这个时候就要做假设检验(如果检验出系数为0说明模型设置有问题,就需要进行调整)。以上是两个不同的步骤和考点。

Kitri.Y · 2020年05月31日

老师您的意思是,在这样的题目中,给出的系数不需要自己做出假设检验的判断,直接带入coefficient 计算就可以了,对么?

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2024-07-13 18:34 1 · 回答

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2023-03-18 14:02 1 · 回答

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2023-01-28 23:09 2 · 回答

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2022-07-10 21:50 1 · 回答