问题如下:
If a portfolio has 80 securities, the number of covariances that should be estimated is
选项:
A. 6,320.
B. 6,400
C. 3,160
D. 80.
解释:
C is correct. 3,160.
If there are N different securities, then the number of correlations equals N(N - 1 )/2
請問這個公式在哪裡說過?