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.

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图1：平均值为3且方差为1的正态分布。

Figure 1: a normal distribution with mean 3 and variance 1.

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进而得出每种假设角色的平均值，方差及标准差验证该假设角色的存在性、出现频率的稳定性以及对各个片断的影响程度。

Furthermore, the average, variance and standard deviation are processed to testify the existence, occurrence stability and influence of each hypothetical role.

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