题目
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.
答案
C
解析
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.因为协方差为正，所以相关系数为正。一个或两个变量的平均值均为负并不影响相关系数的符号。故选项C是正确的