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Apa yang salah dengan bukti saya tentang Hukum Varians Total?
Menurut Hukum Varians Total, Var(X)=E(Var(X∣Y))+Var(E(X∣Y))Var(X)=E(Var(X∣Y))+Var(E(X∣Y))\operatorname{Var}(X)=\operatorname{E}(\operatorname{Var}(X\mid Y)) + \operatorname{Var}(\operatorname{E}(X\mid Y)) Ketika mencoba membuktikannya, saya menulis Var(X)=E(X−EX)2=E{E[(X−EX)2∣Y]}=E(Var(X∣Y))Var(X)=E(X−EX)2=E{E[(X−EX)2∣Y]}=E(Var(X∣Y)) \begin{equation} \begin{aligned} \operatorname{Var}(X) &= \operatorname{E}(X - \operatorname{E}X)^2 \\ &= \operatorname{E}\left\{\operatorname{E}\left[(X - \operatorname{E}X)^2\mid Y\right]\right\} \\ &= \operatorname{E}(\operatorname{Var}(X\mid Y)) \end{aligned} \end{equation} Apakah ada yang salah?