样本的方差的均值等于总体的方差

原創 FightingDependent 2020-06-20 14:14

E(s2)
= E(Xi2) - E(X均2)      (此处的X均是均值，不会打)
= D(Xi) + E(X2) - [DX + E(X均)2]      (不是D(X2i))
= D(Xi) + DX均

在这里插入图片描述

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