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 Dositive. The fact that one or both variables have a negative mean does not affect the sign of the correlation coefficient.
这道题中mean这个条件有什么作用?还有一个不理解的就是,covariance大于0推出correlation也大于0是如何得到的呢?correlation不是由covariance除以两个变量的标准差得到的么?这道题的逻辑怎么给他理顺?求助一下,谢谢