演講公告

東海大學統計學系學術演講20180109

公告時間:2017-12-21 14:59:53
公告單位:統計學系

 

 

東海大學統計學系學術演講

間:10719日(星期二下午14:10~15:00

點:管理學院新大樓M146

主講人:黃彥棕   副研究員 (中研院統計研究所)

題:Tests of Mediation under a Composite Null Hypothesis    

Abstract

Mediation effect of an exposure on an outcome via a mediator involves of two parameters, one for the exposure-mediator association,  , and the other for the mediator-outcome association conditional on the exposure, . Hypothesis tests are conducted under a composite null where at least one of and is zero. This paper studies various hypothesis tests for the mediation effect in the settings of a single test and multiple tests. Under a single test, we show that joint significance test examining the two parameters separately is an intersection-union test with size , and has smaller p-values than normality-based or normal product-based tests for . However, in the setting with multiple tests, the joint significance test has low power because it fails to account for the composition of different null hypotheses. To this end, we develop a new testing procedure under the composite null hypothesis. We show that the composition of null hypotheses can be adjusted by variances of test statistics without directly estimating the proportion of respective nulls. Advantages of the new test are illustrated in simulation and the epigenomic study.

 

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