如果距离均值的变动很大，那么这个平方数也会很大。

If it moves a lot — either way from the mean — then this number squared is a big number.

youdao

然后你减去e的平均值，这个量再平方。

And then you minus the average of e, the quantity squared.

youdao

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.

youdao

If it moves a lot--either way from the mean-- then this number squared is a big number.

如果距离均值的变动很大,那么这个平方数也会很大

耶鲁公开课 - 金融市场课程节选

What we want to do now is compute the mean and variance of the portfolio-- or the mean and standard deviation, since standard deviation is the square root of the variance-- for different combinations of the portfolios.

我们现在要做的是,计算这个投资组合的均值和方差-,或者均值和标准差，因为标准差的平方就等于方差-,这对任何投资组合都是一样的。

耶鲁公开课 - 金融市场课程节选

When we have n observations it's just the summation i = 1 to n of 2/n.

当有n个观察值,这就是在i取1到n时,x减去x均值的平方,除以n的累加

耶鲁公开课 - 金融市场课程节选