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。

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The average size is 3,131 square feet, with a standard deviation of 655 square feet. (Standard deviation is a statistical measure of variance.)

平均大小为 3,131 平方英尺，标准偏差为 655 平方英尺（标准偏差是一个描述差异的统计量度）。

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The standard deviation is the square root of the variance.

标准差是方差的平方根。

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The standard deviation is the square root of the variance.

标准差是方差的平方根

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