Cited by 11,829Gene expression and cancer classificationBioinformatics and Genomic NetworksGenomics and Phylogenetic Studies

Linear Models and Empirical Bayes Methods for Assessing Differential Expression in Microarray Experiments

Smyth, Gordon K·2004·Statistical Applications in Genetics and Molecular Biology

Abstract

The problem of identifying differentially expressed genes in designed microarray experiments is considered. Lonnstedt and Speed (2002) derived an expression for the posterior odds of differential expression in a replicated two-color experiment using a simple hierarchical parametric model. The purpose of this paper is to develop the hierarchical model of Lonnstedt and Speed (2002) into a practical approach for general microarray experiments with arbitrary numbers of treatments and RNA samples. The model is reset in the context of general linear models with arbitrary coefficients and contrasts of interest. The approach applies equally well to both single channel and two color microarray experiments. Consistent, closed form estimators are derived for the hyperparameters in the model. The estimators proposed have robust behavior even for small numbers of arrays and allow for incomplete data arising from spot filtering or spot quality weights. The posterior odds statistic is reformulated in terms of a moderated t-statistic in which posterior residual standard deviations are used in place of ordinary standard deviations. The empirical Bayes approach is equivalent to shrinkage of the estimated sample variances towards a pooled estimate, resulting in far more stable inference when the number of arrays is small. The use of moderated t-statistics has the advantage over the posterior odds that the number of hyperparameters which need to estimated is reduced; in particular, knowledge of the non-null prior for the fold changes are not required. The moderated t-statistic is shown to follow a t-distribution with augmented degrees of freedom. The moderated t inferential approach extends to accommodate tests of composite null hypotheses through the use of moderated F-statistics. The performance of the methods is demonstrated in a simulation study. Results are presented for two publicly available data sets.

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Crossref · 10.2202/1544-6115.1027

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Authors
Smyth, G. K.
Affiliations
Walter and Eliza Hall Institute of Medical Research (AU)
Corresponding author
Smyth, Gordon K
Venue
Statistical Applications in Genetics and Molecular Biology
Published
2004-01-12
Volume
3
Issue
1
Pages
1-25
ISSN
1544-6115 (ISSN-L)
OpenAlex
W2081098333
Cited by
11,829
References
30
Citations by year
2026: 214 · 2025: 252 · 2024: 324 · 2023: 427 · 2022: 374 · 2021: 464 · 2020: 534 · 2019: 510 · 2018: 550 · 2017: 634 · 2016: 718 · 2015: 892 · 2014: 901 · 2013: 917 · 2012: 982
FWCI
78.27
Type
journal article
Language
en
Open access
closed
Locations
  • Statistical Applications in Genetics and Molecular Biology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gene expression and cancer classification
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Bioinformatics and Genomic Networks
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Genomics and Phylogenetic Studies
Keywords
differential gene expression, microarray experiments, empirical Bayes, hierarchical models, posterior odds, hyperparameter estimation, composite null hypothesis, two-color microarrays

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