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[問題] 統計學關於中位數的算法
Oct 29th 2014, 21:38, by incessantgas

作者incessantgas (熱力四射)

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標題[問題] 統計學關於中位數的算法

時間Wed Oct 29 21:38:17 2014

給定一串數字,由大到小排列, 254, 278, 323, 330, 334, 512, 640, 692, 750, 3200 關於四分位數的算法: ##傳統算法: Q1 = [(1/4)*10] = 3rd Q2 = [(2/4)*10] = 5 ---> 整除,故 Q2 = (5th + 6th)/2 Q3 = [(3/4)*10] = 8th 所以上面數列的4分位數為: Q1 = 323 Q2 = (334 + 512)/2 = 423 Q3 = 750 ##Excel算法(interpolation??)以percentile.exc為例: 先算 (n-1)*p= j + g 再算 (1-g)*x(j+1) + g*x(j+2) (10-1)*0.25 = 2 + 0.25 Q1 = (1-g)*x(3) + (g)*x(4) Q1 = 0.75*323 + 0.25*330 = 324.75 (10-1)*0.50 = 4 + 0.5 Q2 = (1-g)*x(5) + (g)*x(6) Q2 = 0.5*334 + 0.25*512 = 423 (10-1)*0.75 = 6 + 0.75 Q3 = (1-g)*x(7) + (g)*x(8) Q3 = 0.25*640 + 0.75*692 = 679 所以, Q1 = 324.75 Q2 = 423 Q3 = 679 比較兩種方法,傳統算法和Excel算法有一些不一致,尤其是Q3,750和679差異頗大。 小弟朋友目前在準備國考,有參考坊間補習班的國考解答,居然是用Excel的複雜算法在 解題。 一般統計教科書(商管經濟類組非統計組)只有教簡單算法, 這讓我超級認真的朋友很困惑。 到底如果考試的時候遇到計算分位數(中位數),要用哪一種算法為準? 謝謝大家耐心看完,拜託各位高手給點意見吧~~~ -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 140.109.122.187 ※ 文章網址: http://www.ptt.cc/bbs/Examination/M.1414589900.A.851.html

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