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J型-發散統計量與數種適合度檢定統計量之比較 / Comparisons of J-divergence statistic with some goodness-of-fit test statistic吳裕陽, Wu, Yuh Yang Unknown Date (has links)
Taneichi(1993)提出一個新的適合度檢定統計量J<sup>2</sup>,具有近似卡方分配的性質。然而在小樣本的情形下,計算機模擬結果顯示,它的估計顯著水準大於期望顯著水準。所以本論文的重點之一,就是對J<sup>2</sup>進行改進,根據不同的準則,來選取一個適當的常數a。我們建議對每一觀測次數加一常數0.32,作為我們修正後的統計量,這個統計量我們記為J<sub>1</sub><sup>2</sup>。
另一探討的重點是在比較皮爾生卡方統計量X<sup>2</sup>,概似比例統計量G<sup>2</sup>,Cressie & Read統計量 I(2/3),J<sup>2</sup>和J<sub>1</sub><sup>2</sup>之性質,我們想要了解在小樣本的情形之下,何者較接近於卡方分配,何者具有較強的檢定力。研究結果顯示,X<sup>2</sup>和I(2/3)較接近卡方分配,但J<sub>1</sub><sup>2</sup>又較G<sup>2</sup>及J<sup>2</sup>好;至於檢定力,我們發現沒有一個統計量在文中所探討的對立假設的情況下,同時都具有最大的檢定力。這些現象都可以用觀測次數對期望次數比值間的關係來解釋。 / Taneichi(1993) introduces a new goodness-of-fit statisticJ<sup>2</sup>, which has an asymptotic chi-squared distribution. However, the results of simulation indicate that the levels of significance are in general bigger than the nominal levels, which prompts us to device a version of J<sup>2</sup> statistic which would perform better under small sample size situations. We suggest adding 0.32 to each observed value and find that the adjustment indeed works rearonably well. This version of J^2 statistic is denoted as J(1)^2.
Although Pearson chi-square statistic X<sup>2</sup>, likelihood ratio statistic G<sup>2</sup>, Cresse-Read statistic I(2/3), J^2 and J(1) ^2 all have asymptotic chi-squared distributions, their small sample behaviors are not expected to be the same. Comparisons based on simulation studies are then made. The conclusions are as follows : (1) In terms of levels of significance, X<sup>2</sup> and I(2/3) behave more like a chi-squared distribution. Though J(1) ^2 does not perform as good as X<sup>2</sup> and I(2/3), it does outperform G<sup>2</sup> and J<sup>2</sup>. (2) In terms of powers, it does not seem that any of the test statistics has a clear advantage over the others.
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基因晶片實驗其樣本數之研究 / Sample Size Determination in a Microarray Experiment黃東溪, Huang, Dong-Si Unknown Date (has links)
微陣列晶片是發展及應用較為成熟的生物晶片技術。由於微陣列實驗程序複雜,故資料常包含多種不同來源的實驗誤差,為了適當的區分實驗中來自處理、晶片及基因的效應,我們提出混合效應變異數分析模型來調整系統誤差。針對各基因在不同實驗環境的差異性假設檢定問題,利用最小平方法推導出點估計以及對應的檢定統計量。本研究介紹多重檢定問題中的族型一誤差,並證明在此模型下,Sidak調整法為適當的多重檢定方法。在給定族型一誤差率的顯著水準,利用檢定力的公式,運算出在預設檢定力的最低水準下所需最小樣本(晶片)數。最後我們透過電腦模擬,以蒙地卡羅法來估計檢定力與族型一誤差率,由模擬結果發現,採用此最小樣本數結果,其檢定力可達到預期的水準以上,並且其族型一誤差率皆適當地控制在顯著水準以內。
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複迴歸係數排列檢定方法探討 / Methods for testing significance of partial regression coefficients in regression model闕靖元, Chueh, Ching Yuan Unknown Date (has links)
在傳統的迴歸模型架構下,統計推論的進行需要假設誤差項之間相互獨立,且來自於常態分配。當理論模型假設條件無法達成的時候,排列檢定(permutation tests)這種無母數的統計方法通常會是可行的替代方法。
在以往的文獻中,應用於複迴歸模型(multiple regression)之係數排列檢定方法主要以樞紐統計量(pivotal quantity)作為檢定統計量,進而探討不同排列檢定方式的差異。本文除了採用t統計量這一個樞紐統計量作為檢定統計量的排列檢定方式外,亦納入以非樞紐統計量的迴歸係數估計量b22所建構而成的排列檢定方式,藉由蒙地卡羅模擬方法,比較以此兩類檢定方式之型一誤差(type I error)機率以及檢定力(power),並觀察其可行性以及適用時機。模擬結果顯示,在解釋變數間不相關且誤差分配較不偏斜的情形下,Freedman and Lane (1983)、Levin and Robbins (1983)、Kennedy (1995)之排列方法在樣本數大時適用b2統計量,且其檢定力較使用t2統計量高,但差異程度不大;若解釋變數間呈現高度相關,則不論誤差的偏斜狀態,Freedman and Lane (1983)、Kennedy (1995) 之排列方法於樣本數大時適用b2統計量,其檢定力結果也較使用t2統計量高,而且兩者的差異程度比起解釋變數間不相關時更加明顯。整體而言,使用t2統計量適用的場合較廣;相反的,使用b2的模擬結果則常需視樣本數大小以及解釋變數間相關性而定。 / In traditional linear models, error term are usually assumed to be independently, identically, normally distributed with mean zero and a constant variance. When the assumptions cannot meet, permutation tests can be an alternative method.
Several permutation tests have been proposed to test the significance of a partial regression coefficient in a multiple regression model. t=b⁄(se(b)), an asymptotically pivotal quantity, is usually preferred and suggested as the test statistic. In this study, we take not only t statistics, but also the estimates of the partial regression coefficient as our test statistics. Their performance are compared in terms of the probability of committing a type I error and the power through the use of Monte Carlo simulation method. Situations where estimates of the partial regression coefficients may outperform t statistics are discussed.
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排列檢定法應用於空間資料之比較 / Permutation test on spatial comparison王信忠, Wang, Hsin-Chung Unknown Date (has links)
本論文主要是探討在二維度空間上二母體分佈是否一致。我們利用排列
(permutation)檢定方法來做比較, 並藉由費雪(Fisher)正確檢定方法的想法而提出重標記 (relabel)排列檢定方法或稱為費雪排列檢定法。
我們透過可交換性的特質證明它是正確 (exact) 的並且比 Syrjala (1996)所建議的排列檢定方法有更高的檢定力 (power)。
本論文另提出二個空間模型: spatial multinomial-relative-log-normal 模型 與 spatial Poisson-relative-log-normal 模型
來配適一般在漁業中常有的右斜長尾次數分佈並包含很多0 的空間資料。另外一般物種可能因天性或自然環境因素像食物、溫度等影響而有群聚行為發生, 這二個模型亦可描述出空間資料的群聚現象以做適當的推論。 / This thesis proposes the relabel (Fisher's) permutation test inspired by Fisher's exact test to compare between distributions of two (fishery) data sets locating on a two-dimensional lattice. We show that the permutation test given by Syrjala (1996} is not exact, but our relabel permutation test is exact and, additionally, more powerful.
This thesis also studies two spatial models: the spatial multinomial-relative-log-normal model and the spatial
Poisson-relative-log-normal model. Both models not only exhibit characteristics of skewness with a long right-hand tail and of high proportion of zero catches which usually appear in fishery data, but also have the ability to describe various types of aggregative behaviors.
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