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事故傾向服從Inverse Gaussian分配時混合Weibull模式之研究黃(糸秀)琪, Huang,Hsiu-Chi Unknown Date (has links)
本篇論文主要考慮成群資料的存活分析,其特點為群內個體間具有相關性,並假定群內個體具有相同但無法觀測到的事故傾向。首先,探討事故傾向服從任一連續分配時混合Weibull迴歸模式的特性,接著,推導出事故傾向服從血Inverse Gaussian吧時之混合Weibull模式,並介紹參數的估計問題。然後,推導出群內個體是否獨立之分數檢定統計量,以分別就兩種最常見的存活資料型態一完整型態與右設限型態:檢定模式中事故傾向的效應是否存在。最後,並以實例說明分數檢定之程序。 / In this paper, we study survival analysis for grouped data, where the within group correlations are considered. It is also assumed that individuals within the same group share a common but unobservable random frailty. First, we discuss the properties of the Weibull regression model mixed by any continuous distribution. Next, we derive an Inverse Gaussan mixture of Weibull regression model, and discuss the estimation problem. Then, we derive the score test for testing independence between components within the same group, where the two most common cases are discussed the complete data case and the right censoring case. Finally, the testing procedures are illustrated by two examples.
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具有額外或不足變異的群集類別資料之研究 / A Study of Modelling Categorical Data with Overdispersion or Underdispersion蘇聖珠, Su, Sheng-Chu Unknown Date (has links)
進行調查時,最後的抽樣單位常是從不同的群集取得的,而同一群集內的樣本對象,因背景類似而對於某些問題常會傾向相同或類似的反應,研究者若忽略這種群內相關性,仍以獨立性樣本進行分析時,因其共變異數矩陣通常會與多項模式的共變異數矩陣相差懸殊,而造成所謂的額外變異或不足變異的現象。本文在不同的情況下,提出了Dirichlet-Multinomial模式(簡稱DM模式)、擴展的DM模式、以及兩種平均數-共變異數矩陣模式,以適當的彙整所有的群集資料。並討論DM與EDM模式中相關之參數及格機率之最大概似估計法,且分別對此兩種平均數-共變異數矩陣模式,提出求導廣義最小平方估計的程序。此外,也針對幾種特殊的二維表及三維表結構,探討對應的參數及格機率之估計方法。並提出計算簡易的Score統計檢定量以判斷群內相關(intra-cluster correlation)之存在性,及判斷資料集具有額外或不足變異,而對於不同母體的群內相關同質性檢定亦提出討論。 / This paper presents a modelling method of analyzing categorical data with overdispersion or underdispersion. In many studies, data are collected from differ clusters, and members within the same cluster behave similary. Thus, the responses of members within the same cluster are not independent and the multinomial distribution is not the correct distribution for the observed counts. Therefore, the covariance matrix of the sample proportion vector tends to be much different from that of the multinomial model. We discuss four different models to fit counts data with overdispersion or underdispersion feature, witch include Dirichlet-Multinomial model (DM model), extended DM model (EDM model), and two mean-covariance models. Method of maximum-likelihood estimation is discussed for DM and EDM models. Procedures to derive generalized least squares estimates are proposed for the two mean-covariance models respectively. As to the cell probabilities, we also discuss how to estimate them under several special structures of two-way and three-way tables. More easily evaluated Score test statistics are derived for the DM and EDM models to test the existence of the intra-cluster correlation. And the test of homogeneity of intra-cluster correlation among several populations is also derived.
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