问题如下：
Wei Liu makes two statements about active portfolio management:
Statement 1
The "active return" of an actively managed portfolio is the difference between the portfolio’s return and the return on the benchmark portfolio, and is equal to the managed portfolio’s alpha.
Statement 2
The active weights are the differences in the managed portfolio’s weights and the benchmark’s weights.
Are Liu’s statements correct?
选项：
A.Only Statement 1 is correct.
B.Only Statement 2 is correct.
C.Both statements are correct.
解释：
B is correct.
Although the first part of Statement 1 is correct (active return, or value added, equals the difference between the managed portfolio return and the benchmark return), active return is not the same as alpha. In other words, RA=RP-RB, while
. Statement 2 correctly defines active weights.
考点：value added
解析： Statement 1 前半句正确， RA=RP-RB ，但后半句错，alpha不是active return，而是风险调整后的value added,。Statement 2说法正确。考的是定义。
您好，想继续询问一下关于我们对active return 和alpha的理解。
一是关于active return，或者value added，我们说的是投资组合的收益高于benchmark的收益的部分，即Rp-Rb，对么，这个比较好理解。
二是关于alpha，这个看到是在单因子模型中出现的，即用Rp-beta*Rb，关于实际意义的话，想问一下alpha如何理解呢，是风险加权后的超额收益么？那么一般我们说衡量超额收益一般用Rp-Rb比较好一些还是alpha呢？
谢谢
