The variance of a random variable measures how far from the expected value its values typically are.
随机变量的方差衡量随机变量值与期望值偏离的程度。
Expected value is good and variance is bad because that's risk; that's uncertainty.
期望值越高越好,方差就相反,因为方差代表着风险,也就是不确定性
We want a high expected value of returns, but we don't like variance.
我们希望收益的期望值较高,并且稳定
The technical definition of variance is the random variable's second central moment, the weighted average of the square of the differences from the expected value.
3方差的专业定义是随机变量的二次中心矩，与期望值之差的平方的加权平均值。
The technical definition of variance is the random variable's second central moment, the weighted average of the square of the differences from the expected value.
3方差的专业定义是随机变量的二次中心矩，与期望值之差的平方的加权平均值。
应用推荐