推 ltisld:謝謝你喔^^ 02/15 20:26
※ 引述《ltisld ()》之銘言：
: 是研究所考古題
: 和室友兩人研究許久後仍不得其法
: 希望有先進能指點一二^^
: 93台大商研
: Let X and Y equal the concentration in parts per billion of chromium in the
: blood for healthy persons and for persons with a suspected disease, repectively.
: Assume that the diftribution of X and Y are N(μ_x, σ^2_x) and
: N(μ_y, σ^2_y). Using n=8 observationsof X: 15, 23, 12, 18, 9, 28, 11, 10
: and m=10 observations of Y:25, 20, 35, 15, 40, 16, 10, 22, 18, 32.
Find a one sided 95% condifence interval that is an upper bound for
σ^2_x/σ^2_y
由於是要算兩母體變異數比之CI,使用的是F分配
所以CI的下界一定是0
故只要算上界就好
由題知 P( F(0.95,7,9)<F<無窮大 )=0.95
則 Upper bound = (Sx^2/ Sy^2)*F(0.05,9,7)
故 σ^2_x/σ^2_y之單尾95%的CI為 (0,1.835) #
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也許我們都已經活得太自由 忘了該預習自慚形穢的本能......
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