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

耶鲁公开课 - 金融市场课程节选

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

耶鲁公开课 - 金融市场课程节选