第二部分是有关平稳随机变量均值的函数表达式及其有关术语。
The second Part is about the exPression of Average stutistics. values for stationary chance variable and its terms concerned.
随机变量的加权平均值是期望值。
The weighted mean of the random variable is 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。
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.
应用推荐