NO.PZ2020012201000020
问题如下:
Which of the following statements regarding the advantages of "A factor-model-based VCV matrix " is incorrect?
选项:
A. This method can be used even if the number of assets exceeds the number of observations.
B. This method can substantially reduce the number of unique parameters to be estimated,
C. the VCV matrix will be correct on average
解释:
C is correct.
解析:
对于A factor-model-based VCV matrix " 这种方法,即使资产的数量超过观测值的数量也可以使用。而且它可以大大减少需要估计的参数的数量。所以AB选项说法正确。
但平均而言,VCV矩阵是不准确的,因为这种方法是有偏的。所以C选项的说法是不正确的。入选。
题干中的average是不是就是书上对应的expected value?也就是multi factor model缺点之一biased,expected value并不等于真实的VCV matrix,原因是因为什么?模型本身有偏?