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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

複雜抽樣設計下邏輯斯迴歸模式之分析

劉國輝 Unknown Date (has links)
當反應變數是二元(binary)時,邏輯斯迴歸(logistic regression)可幫助我們建立解釋變數與反應變數間的關係。然而,一般在進行邏輯斯迴歸分析時,總是假設樣本資料是由簡單隨機抽樣(simple random sampling)所取得,亦即所有的樣本皆具有相同的抽樣權重(sampling weights)。不過,在實務上,許多的大型抽樣調查都是採用複雜抽樣方法(complex sampling method)來抽取樣本。例如:採用多階段抽樣(multistage sampling)結合分層抽樣(stratified sampling)或是群集抽樣(cluster sampling)的方式來進行抽樣。由於樣本不再是以簡單隨機抽樣所取得,因此,統計分析的方式可分為兩類:一類乃設計導向(design-based);另一類則為模式導向(model-based)。其中,若將抽樣調查的抽樣設計方式以及樣本的代表性與統計模式的估計或檢定等推論過程相結合,則其屬於設計導向之方式。反之,若忽略這些因素,則相當於視調查資料來自於簡單隨機樣本,仍遵循一般的程序進行分析,則稱之為模式導向。本論文旨在探討如何以設計導向的方法,進行複雜抽樣方法所取得樣本資料的邏輯斯迴歸分析。
2

含存活分率之貝氏迴歸模式

李涵君 Unknown Date (has links)
當母體中有部份對象因被治癒或免疫而不會失敗時,需考慮這群對象所佔的比率,即存活分率。本文主要在探討如何以貝氏方法對含存活分率之治癒率模式進行分析,並特別針對兩種含存活分率的迴歸模式,分別是Weibull迴歸模式以及對數邏輯斯迴歸模式,導出概似函數與各參數之完全條件後驗分配及其性質。由於聯合後驗分配相當複雜,各參數之邊際後驗分配之解析形式很難表達出。所以,我們採用了馬可夫鏈蒙地卡羅方法(MCMC)中的Gibbs抽樣法及Metropolis法,模擬產生參數值,以進行貝氏分析。實證部份,我們分析了黑色素皮膚癌的資料,這是由美國Eastern Cooperative Oncology Group所進行的第三階段臨床試驗研究。有關模式選取的部份,我們先分別求出各對象在每個模式之下的條件預測指標(CPO),再據以算出各模式的對數擬邊際概似函數值(LPML),以比較各模式之適合性。 / When we face the problem that part of subjects have been cured or are immune so they never fail, we need to consider the fraction of this group among the whole population, which is the so called survival fraction. This article discuss that how to analyze cure rate models containing survival fraction based on Bayesian method. Two cure rate models containing survival fraction are focused; one is based on the Weibull regression model and the other is based on the log-logistic regression model. Then, we derive likelihood functions and full conditional posterior distributions under these two models. Since joint posterior distributions are both complicated, and marginal posterior distributions don’t have closed form, we take Gibbs sampling and Metropolis sampling of Markov Monte Carlo chain method to simulate parameter values. We illustrate how to conduct Bayesian analysis by using the data from a melanoma clinical trial in the third stage conducted by Eastern Cooperative Oncology Group. To do model selection, we compute the conditional predictive ordinate (CPO) for every subject under each model, then the goodness is determined by the comparing the value of log of pseudomarginal likelihood (LPML) of each model.

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