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Open Access Open Badges Methodology article

Rank Difference Analysis of Microarrays (RDAM), a novel approach to statistical analysis of microarray expression profiling data

Dietmar E Martin1, Philippe Demougin1, Michael N Hall1 and Michel Bellis2*

Author Affiliations

1 Biozentrum, University of Basel, CH-4056 Basel, Switzerland

2 CRBM, FRE2593, CNRS, Montpellier, France

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BMC Bioinformatics 2004, 5:148  doi:10.1186/1471-2105-5-148

Published: 11 October 2004



A key step in the analysis of microarray expression profiling data is the identification of genes that display statistically significant changes in expression signals between two biological conditions.


We describe a new method, Rank Difference Analysis of Microarrays (RDAM), which estimates the total number of truly varying genes and assigns a p-value to each signal variation. Information on a group of differentially expressed genes includes the sensitivity and the false discovery rate. We demonstrate the feasibility and efficiency of our approach by applying it to a large synthetic expression data set and to a biological data set obtained by comparing vegetatively-growing wild type and tor2-mutant yeast strains. In both cases we observed a significant improvement of the power of analysis when our method is compared to another popular nonparametric method.


This study provided a valuable new statistical method to analyze microarray data. We conclude that the good quality of the results obtained by RDAM is mainly due to the quasi-perfect equalization of variation distribution, which is related to the standardization procedure used and to the measurement of variation by rank difference.