when you're advertising your return you want to make it look

他们为自己的收益率做广告时
as big as possible.

当然希望数字越大越好
We also need some measure of--

我们也需要其他的指标
We've been talking here about measures of central tendency only

目前为止我们只讨论了集中趋势指标
and in finance we need, as well,

在金融学中我们同样需要
measures of dispersion, which is how much something varies.

离散趋势指标以衡量参数的变化程度
Central tendency is a measure of the center

集中趋势用以描述
of a probability distribution of the--

一组概率分布的中心
Central tendency is a measure--

集中趋势...
Variance is a measure of how much things change

而方差衡量的是
from one observation to another.

各个观察值之间的变化
We have variance and it's often represented by σ2,

方差这个指标我们通常写作σ2