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Weike · 2024年03月13日

学习成绩和学习时间为什么违反同质化,房子的价格和年限违反的就是独立性

NO.PZ2023062701000012

问题如下:

A researcher is conducting a study to examine the relationship between the amount of time spent studying and the scores achieved on a final exam. The researcher collects data from a sample of 100 students. Which of the following assumptions of linear regression is most likely to be violated in this study?

选项:

A.

Linearity

B.

Homoskedasticity

C.

Independence

解释:

In this study, the assumption of homoskedasticity is most likely to be violated. Homoskedasticity in linear regression assumes that the variance of the residuals (the difference between observed and predicted values) is constant across all levels of the independent variable. However, in the context of studying, it is plausible to assume that the variance of scores achieved on the final exam may differ depending on the amount of time spent studying. For example, students who study for longer periods might have more consistent and less variable exam scores compared to those who study less. Therefore, the assumption of homoskedasticity may not hold in this study.

学习成绩和学习时间为什么违反同质化,房子的价格和年限违反的就是独立性

2 个答案

执火 · 2024年03月29日

品职助教_七七 · 2024年03月13日

嗨,爱思考的PZer你好:


本题和“房子的价格和年限”无关,也没有同质化这个概念,Homoskedasticity为同方差。同方差/异方差描述方程的残差项的波动性是否随着自变量X的变动而变化。

答案解析认为,学习时间短的学生成绩不稳定,实际成绩波动性大,导致残差(实际成绩-预测成绩)的波动也大。学习时间更长的人成绩会比较稳定,从而实际成绩-预测成绩的波动也小,残差也稳定。

上述内容体现出了残差的波动性随着学习时间的变化(X变量的变化)而发生变化,构成(条件)异方差,从而违反了同方差的假设。

这道题出的有点别扭,了解一下答案给的思路即可。

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对于有明确解析的题目,提问时请具体说明不理解的地方,避免无效的重复讲解。

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