报告题目：A Marginalized Two-Part Beta Regression Model for Microbiome Compositional Data

报 告 人：刘磊教授(美国西北大学)

报告时间：2017年6月19日下午3:00-4:00

报告地点：知新楼B1238室

报告摘要：In microbiome studies, one important goal is to detect differential abundance of microbes across clinical conditions and treatment options. However, the microbiome compositional data (denoted by relative abundance) are highly skewed, bounded in [0, 1), and often with many zeros. A two-part model is commonly used to separate zeros and positive values explicitly by two submodels: a logistic model for the probability of a specie being present in Part I, and a Beta regression model for the relative abundance conditional on the presence of the specie in Part II. However, the regression coefficients in Part II cannot provide a marginal (unconditional) interpretation of covariate effects on the microbial abundance, which is of great interest in many applications. In this paper, we propose a marginalized two-part Beta regression model which captures the zero-inflation and skewness of microbiome data and also allows investigators to examine covariate effects on the marginal (unconditional) mean. We demonstrate its practical performance using simulation studies and apply the model to a real metagenomic dataset on mouse skin microbiota. We find that under the proposed marginalized model, without loss in power, the likelihood ratio test performs better in controlling the type I error than those under conventional methods.

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