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安在 · 2022年09月08日

没理解

NO.PZ2021061603000034

问题如下:

Consider two variables, A and B. If variable A has a mean of-0.56, variable B has a mean of 0.23, and the covariance between the two variables is positive, the correlation between these two variables is:

选项:

A.negative. B.zero. C.positive.

解释:

C is correct.

The correlation coefficient is positive because the covariance is positive. The fact that one or both variables have a negative mean does not affect the sign of the correlation coefficient.

根据公式 :R=S/两个标准差的乘积, S是positive 那就是正号 ,标准差一正一负,然后相除以后得到CORRELATION,就是负的 所以是negative ,哪里理解错了?

1 个答案

星星_品职助教 · 2022年09月09日

同学你好,

一正一负的是均值而非标准差。

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