→ kaka5566:SORRY~打錯XD 04/07 11:55
→ kaka5566:σ is α×S 04/07 11:56
※ 引述《kavas (卡瓦士)》之銘言：
: 4.
: Assume Y1,Y2,Y3......Yn be a ramdom sample of size n from the
: normal distribution N(μ,σ^2). We find that an unbiased estimator
: for σ is α×x and an unbiased estimator for σ^2 is β×S^2 ,
: where S= √ [Σ(Yi-Ybar)^2]
: (a) What is the value of α?
: (b) What is the value of β?
: 可以給我點提示嗎?或是教教我T_T
: 謝謝大家~謝謝
x是?
E[βS^2] = σ^2
Σ(Yi-Ybar)^2 1
W = ------------- ~ Chi(n-1) , E(W) = n-1 β = -----
σ^2 n-1
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