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铭倩 · 2022年01月18日

C选项

  1. CFA I
  2. Quantitative

NO.PZ2021062201000019

问题如下：

Which of the following statements is correct regarding the chi-square test of independence?

选项：

A.

The test has a one-sided rejection region.

B.

The null hypothesis is that the two groups are dependent.

C.

If there are two categories, each with three levels or groups, there are six degrees of freedom.

解释：

A is correct. The test statistic comprises squared differences between the observed and expected values, so the test involves only one side, the right side.

B is incorrect because the null hypothesis is that the groups are independent, and C is incorrect because with three levels of groups for the two categorical variables, there are four degrees of freedom.

本题考察关于卡方检验的概念，由于检验统计量包含观测值和预期值之间的平方差，因此检验仅涉及一侧，即右侧，所以选A。


请老师解释一下C选项以及考点
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1 个答案

星星_品职助教 · 2022年01月18日

同学你好，

这道题基础班上课已经讲过。对于两个“three levels”的categories，自由度应是（3-1）×（3-1）=4.

考点为截图红框中的公式。

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