开发者:上海品职教育科技有限公司 隐私政策详情

应用版本:4.2.11(IOS)|3.2.5(安卓)APP下载

🍑(o^^o)Fay 🙃 · 2022年08月16日

根据多重共线性的判断规则,为什么adjust r2不增加

* 问题详情,请 查看题干

NO.PZ201709270100000305

问题如下:

5. Based on Exhibit 2, Quinni’s best answer to Varden’s question about the effect of adding a third independent variable is:

选项:

A.

no for R2 and no for adjusted R2.

B.

yes for R2 and no for adjusted R2.

C.

yes for R2 and yes for adjusted R2.

解释:

B is correct. When you add an additional independent variable to the regression model, the amount of unexplained variance will decrease, provided the new variable explains any of the previously unexplained variation. This result occurs as long as the new variable is even slightly correlated with the dependent variable. Exhibit 2 indicates the dividend growth rate is correlated with the dependent variable, ROE. Therefore, R2 will increase.

Adjusted R2, however, may not increase and may even decrease if the relationship is weak. This result occurs because in the formula for adjusted R2, the new variable increases k (the number of independent variables) in the denominator, and the increase in R2 may be insufficient to increase the value of the formula.

textadjustedR2=1(n1nk1)(1R2text{adjusted R}^\text{2}=1-(\frac{n-1}{n-k-1})(1-R^2

我感觉这题在考察:多重共线性情况下 adjust r^2的影响,如果多重共线性发生,自变量之间的 correlation 过高,就会有使得r^2上升,但是adj r^2 下降。我是这么理解的,但是这道题,我不知道怎么得出 no for adj r^2 的

2 个答案
已采纳答案

星星_品职助教 · 2022年08月16日

@🍑(o^^o)Fay 🙃

如果新增变量对于方程的贡献度不大,adjusted R-squared会降低;如果新增变量对于方程有很大贡献,adjusted R-squared会上升。

通过题干里的Exhibit 2,可以看出新变量和Y变量的相关系数非常低,这就是在提示新变量对方程的贡献度不够。

这种情况下,adjusted R-squred是下降的。

星星_品职助教 · 2022年08月16日

同学你好,

这道题不是考察多重共线性的。可以从Exhibit 2中看出,新加X变量Divgr和方程里已有的两个变量的相关性都不高,不会导致多重共线性(新加入的变量和方程已有变量高度相关)

本题考察的是在方程中新加入X变量,对R-squared和adjusted R-squared分别的影响,结论为:

1)只要方程里加入X,那么R-squared一定会上升;

2)只有新加入的X对方程有比较大的贡献,adjusted R-squared才会上升。根据Exhibit 2,新变量divgr和Y变量的相关性非常小,解释力度低,所以此时adjusted R-squred不会上升。


🍑(o^^o)Fay 🙃 · 2022年08月16日

老师 我怎么判断adjust r^2  的大小

  • 2

    回答
  • 1

    关注
  • 373

    浏览
相关问题

NO.PZ201709270100000305 问题如下 BrVarn, a junior analyst actively managemutufun is responsible for researon a subset of the 500 large-cequities the funfollows. Recently, the funhbeen paying close attention to management turnover anto publicly available environmental, social, angovernan(ESG) ratings. Varn is given the task of investigating whether any significant relationship exists between a company’s profitability aneither of these two characteristics. Colleen Quinni, asenior analyst the fun suggests thinitistep in his investigation,Varn shoulperform a multiple regression analysis on the variables anreport bato her. Varn knows thQuinni is expert quantitative research, anshe ontolVarn thafter you get iyou shoulformulate a hypothesis, test the hypothesis, ananalyze the results. Varn expects to finthESG rating is negatively relateto ROE anCEO tenure is positively relateto ROE. He consirs a relationship meaningful when it is statistically significant the 0.05 level. To begin, Varn collects values for ROE, CEO tenure, anESG rating for a sample of 40 companies from the large-csecurity universe. He performs a multiple regression with ROE (in percent) the pennt variable anESG rating anCEO tenure (in years) the inpennt variables: Yi = + b1X1i +b2X2i + εi. Exhibit 1 shows the regression results. Associates is one of the companies Varn follows. He wants to preits ROE using his regression mol. Associates’ corporate ESG rating is 55, anthe company’s CEO hbeen in thposition for 10.5 years. Varn also wants to cheon the relationship between these variables anthe vingrowth rate (vgr), so he completes the correlation matrix shown in Exhibit 2.Investigating further, Varn termines thvingrowth is not a linecombination of CEO tenure anESG rating. He is uncleabout how aitioninpennt variables woulaffethe significanof the regression, so he asks Quinni, \"Given this correlation matrix, will both R2 anausteR2 automatically increase if I a vingrowth a thirinpennt variable?\" The scussion continues, anQuinni asks two questions.1.Whes your F-statistic of 4.161 tell you about the regression?2.In interpreting the overall significanof your regression mol, whistatistic you believe is most relevant: R2, austeR2, or the F-statistic?Varn answers both questions correctly ansays he wants to chetwo more ias. He believes the following:1. ROE is less correlatewith the vingrowth rate in firms whose CEO hbeen in offimore th15 years, an.CEO tenure is a normally stributeranm variable.Later, Varn inclus the vingrowth rate a thirinpennt variable anruns the regression on the funs entire group of 500 large-cequities. He fin ththe austeR2 is muhigher ththe results in Exhibit 1. He reports this to Quinni ansays, \"Aing the vingrowth rate gives a mol with a higher austeR2. The three-variable mol is clearly better.\" Quinni cautions, \"I n’t think you cconclu thyet.\" 5. Baseon Exhibit 2, Quinni’s best answer to Varn’s question about the effeof aing a thirinpennt variable is: no for R2 anno for austeR2. yes for R2 anno for austeR2. yes for R2 anyes for austeR2. B is correct. When you a aitioninpennt variable to the regression mol, the amount of unexplainevarianwill crease, provithe new variable explains any of the previously unexplainevariation. This result occurs long the new variable is even slightly correlatewith the pennt variable. Exhibit 2 incates the vingrowth rate is correlatewith the pennt variable, ROE. Therefore, R2 will increase.AusteR2, however, mnot increase anmeven crease if the relationship is weak. This result occurs because in the formula for austeR2, the new variable increases k (the number of inpennt variables) in the nominator, anthe increase in R2 minsufficient to increase the value of the formula.textauste2=1−(n−1n−k−1)(1−R2text{austeR}^\text{2}=1-(\frac{n-1}{n-k-1})(1-R^2textauste2=1−(n−k−1n−1​)(1−R2 老师 麻烦一下这题,为什么选B呀,为什么R^2是yes

2024-01-08 23:40 1 · 回答

NO.PZ201709270100000305 问题如下 5. Baseon Exhibit 2, Quinni’s best answer to Varn’s question about the effeof aing a thirinpennt variable is: no for R2 anno for austeR2. yes for R2 anno for austeR2. yes for R2 anyes for austeR2. B is correct. When you a aitioninpennt variable to the regression mol, the amount of unexplainevarianwill crease, provithe new variable explains any of the previously unexplainevariation. This result occurs long the new variable is even slightly correlatewith the pennt variable. Exhibit 2 incates the vingrowth rate is correlatewith the pennt variable, ROE. Therefore, R2 will increase.AusteR2, however, mnot increase anmeven crease if the relationship is weak. This result occurs because in the formula for austeR2, the new variable increases k (the number of inpennt variables) in the nominator, anthe increase in R2 minsufficient to increase the value of the formula.textauste2=1−(n−1n−k−1)(1−R2text{austeR}^\text{2}=1-(\frac{n-1}{n-k-1})(1-R^2textauste2=1−(n−k−1n−1​)(1−R2 另AustR的变化方向是否以1作为标准?而非0.7?

2023-07-30 20:39 1 · 回答

NO.PZ201709270100000305问题如下 5. Baseon Exhibit 2, Quinni’s best answer to Varn’s question about the effeof aing a thirinpennt variable is: no for R2 anno for austeR2. yes for R2 anno for austeR2. yes for R2 anyes for austeR2. B is correct. When you a aitioninpennt variable to the regression mol, the amount of unexplainevarianwill crease, provithe new variable explains any of the previously unexplainevariation. This result occurs long the new variable is even slightly correlatewith the pennt variable. Exhibit 2 incates the vingrowth rate is correlatewith the pennt variable, ROE. Therefore, R2 will increase.AusteR2, however, mnot increase anmeven crease if the relationship is weak. This result occurs because in the formula for austeR2, the new variable increases k (the number of inpennt variables) in the nominator, anthe increase in R2 minsufficient to increase the value of the formula.textauste2=1−(n−1n−k−1)(1−R2text{austeR}^\text{2}=1-(\frac{n-1}{n-k-1})(1-R^2textauste2=1−(n−k−1n−1​)(1−R2 如题????????????我觉得0.1不小啊

2023-01-26 22:29 1 · 回答

NO.PZ201709270100000305 问题如下 5. Baseon Exhibit 2, Quinni’s best answer to Varn’s question about the effeof aing a thirinpennt variable is: no for R2 anno for austeR2. yes for R2 anno for austeR2. yes for R2 anyes for austeR2. B is correct. When you a aitioninpennt variable to the regression mol, the amount of unexplainevarianwill crease, provithe new variable explains any of the previously unexplainevariation. This result occurs long the new variable is even slightly correlatewith the pennt variable. Exhibit 2 incates the vingrowth rate is correlatewith the pennt variable, ROE. Therefore, R2 will increase.AusteR2, however, mnot increase anmeven crease if the relationship is weak. This result occurs because in the formula for austeR2, the new variable increases k (the number of inpennt variables) in the nominator, anthe increase in R2 minsufficient to increase the value of the formula.textauste2=1−(n−1n−k−1)(1−R2text{austeR}^\text{2}=1-(\frac{n-1}{n-k-1})(1-R^2textauste2=1−(n−k−1n−1​)(1−R2 请问0.117和谁对比?

2023-01-23 00:21 2 · 回答