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arXiv 1209.6493stat.AP
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微阵列数据分层模型中基因和基因特异性处理效应不同建模策略的重要性

The importance of distinct modeling strategies for gene and gene-specific treatment effects in hierarchical models for microarray data

Steven P. Lund, Dan Nettleton

摘要:

当分析微阵列数据时,在估计均值和方差或识别差异表达时,分层模型通常用于跨基因共享信息。许多方法利用由Kendziorski等人[Stat. Med.(2003)22 3899-3914],其中第一水平描述了潜在平均表达水平在基因之间和在基因内差异表达处理之间的分布。第二个层次描述的条件分布,给定一个潜在的平均值,一个单一的基因和治疗的重复观察。这些模型中的许多,包括在Kendziorski等人[Stat. Med.(2003)22 3899-3914] EBarrays软件包,假设由于处理效应引起的表达水平变化具有与基因间表达水平变化相同的分布。我们提出的经验证据表明,这种假设往往是不够的,并提出三级分层模型作为扩展的两级对数正态的EBarrays模型,以解决这一不足。我们证明,使用我们的三个层次的模型显着改变了各种微阵列数据集的分析结果,并验证了我们建议的方法在一系列模拟研究的有效性和改进的性能。我们还说明了在使用分层模型识别差异表达基因时考虑基因特异性误差方差估计的不确定性的重要性。

英文摘要:

When analyzing microarray data, hierarchical models are often used to share information across genes when estimating means and variances or identifying differential expression. Many methods utilize some form of the two-level hierarchical model structure suggested by Kendziorski et al. [Stat. Med. (2003) 22 3899-3914] in which the first level describes the distribution of latent mean expression levels among genes and among differentially expressed treatments within a gene. The second level describes the conditional distribution, given a latent mean, of repeated observations for a single gene and treatment. Many of these models, including those used in Kendziorski's et al. [Stat. Med. (2003) 22 3899-3914] EBarrays package, assume that expression level changes due to treatment effects have the same distribution as expression level changes from gene to gene. We present empirical evidence that this assumption is often inadequate and propose three-level hierarchical models as extensions to the two-level log-normal based EBarrays models to address this inadequacy. We demonstrate that use of our three-level models dramatically changes analysis results for a variety of microarray data sets and verify the validity and improved performance of our suggested method in a series of simulation studies. We also illustrate the importance of accounting for the uncertainty of gene-specific error variance estimates when using hierarchical models to identify differentially expressed genes.

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