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dejiazheng · 2024年05月08日

(AR(1)) model 没要求b0 is close to zero吧?

NO.PZ2023040502000038

问题如下:

Eduardo DeMolay, a research analyst at Mumbai Securities, is studying the time series behavior of price-to-earnings ratios (P/Es) computed with trailing 12-month earnings (Etrailing).


DeMolay states: “This regression is a special case of a first-order autoregressive (AR(1)) model in which the value for b0 is close to zero and the value of b1 is close to 1. These values suggest that the time series is a random walk.”

DeMolay's statement that the coefficients depicted in Exhibit 1 are consistent with a random walk is most likely:

选项:

A.

incorrect because b1 should be close to 0.

B.

incorrect because b0 should be close to 1.

C.

correct.

解释:

When modeled using a AR(1) model, as in the formula given in Exhibit 1, random walks will have an estimated intercept coefficient near zero and an estimated slope coefficient on the first lag near 1. Therefore, his statement is correct.

该表述是否有误?

1 个答案

品职助教_七七 · 2024年05月09日

嗨,爱思考的PZer你好:


AR(1)) model 没要求b0 is close to zero吧?----不要求。

这个statement说的是random walk 的b0为0和b1为1。这个描述无误。如果题目只提到了random walk,就当做是simple random walk来处理,即Xt=Xt-1+εt的形式,不考虑b0≠0即with a drift的情况。

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虽然现在很辛苦,但努力过的感觉真的很好,加油!

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NO.PZ2023040502000038 问题如下 Ear Molay, a researanalyst MumbaiSecurities, is stuing the time series behavior of price-to-earnings ratios(P/Es) computewith trailing 12-month earnings (Etrailing).Molstates: “This regression is a specicase of a first-orrautoregressive (AR(1)) mol in whithe value for is close tozero anthe value of is close to 1. These values suggest thatthe time series is a ranm walk.”Molay's statement thatthe coefficients pictein Exhibit 1 are consistent with a ranm walk ismost likely: A.incorrebecause shoulclose to 0. B.incorrebecause shoulclose to 1. C.correct. When moleusing a AR(1) mol, in the formulagiven in Exhibit 1, ranm walks will have estimateintercept coefficientnezero anestimateslope coefficient on the first lne1. Therefore,his statement is correct. (0.991-1)/0.003=-3 ,不是应该reje原假设,那就不是ranm walk啊

2024-04-05 15:22 1 · 回答

NO.PZ2023040502000038 问题如下 Ear Molay, a researanalyst MumbaiSecurities, is stuing the time series behavior of price-to-earnings ratios(P/Es) computewith trailing 12-month earnings (Etrailing).Molstates: “This regression is a specicase of a first-orrautoregressive (AR(1)) mol in whithe value for is close tozero anthe value of is close to 1. These values suggest thatthe time series is a ranm walk.”Molay's statement thatthe coefficients pictein Exhibit 1 are consistent with a ranm walk ismost likely: A.incorrebecause shoulclose to 0. B.incorrebecause shoulclose to 1. C.correct. When moleusing a AR(1) mol, in the formulagiven in Exhibit 1, ranm walks will have estimateintercept coefficientnezero anestimateslope coefficient on the first lne1. Therefore,his statement is correct. 老师,您好!随机游走现象存在时,xt-xt-1 =b0+g xt-1+εt,只要公式中的g = b1-1 = 0,即b1等于1即可吧,对于截距项b0有要求等于0吗?谢谢!

2023-08-03 22:41 1 · 回答