NO.PZ2015120604000057
问题如下：
Molly is studying the return distribution of firm A's stock. She finds that the median of stock returns is smaller than the mean. Which of the following statements about the return distribution is correct?
选项：
A.
The return distribution is positively skewed.
B.
The return distribution is negatively skewed.
C.
The return distribution has a positive excess kurtosis.
解释：
A is correct
For a positively skewed distribution, the mode is less than the median, and the median is less than the mean. There are positive outliers which will tend to pull the mean more positive.
之前的提问中，有回答说kurtosis是衡量尾部情况的参数。
1.skewness不衡量尾部吗？它的尾部不也是变化的吗（fat tail,thin tail）？
2.skewness是衡量什么情况的参数呢？
