碩士 / 國立中興大學 / 統計學研究所 / 100 / Epidemiologic studies concern the effect of an exposure, and a set of explanatory variables, on the outcome variable. When logistic regression model is used and some variables are dichotomized according to possible cutoff points to produce maximally selected test statistics, the distribution of the test statistics under null hypothesis (of ‘no effect’) is proved to be not a chi-square distribution with 1 degree of freedom. It is a distribution of the supremum of the Brownian bridge with suitable correction. This study extends the problem to a logistic regression setting. We investigate the situation of independent explanatory variables towards the power of different tests. When there are correlations among variables, we propose a stepwise pseudo Gram-Schmidt orthogonalization process so that each individual regression parameters can have reasonable type I error. Several methods are proposed, and their powers are compared through simulations. We implement the proposed methods on an actual data set for illustration.
| Identifer | oai:union.ndltd.org:TW/100NCHU5337002 |
| Date | January 2012 |
| Creators | Wei-Ting Yi, 易緯霆 |
| Contributors | 吳宏達 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 54 |
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