A method for enhanced detection and statistical analysis of differentially
expressed genes in gene chip microarrays employs: (a) transformation of
gene expression data into an expression data matrix (image data
paradigm); (b) wavelet denoising of expression data matrix values to
enhance their signal-to-noise ratio; and (c) singular value decomposition
(SVD) of the wavelet-denoised expression data matrix to concentrate most
of the gene expression signal in primary matrix eigenarrays to enhance
the separation of true gene expression values from background noise. The
transformation of gene chip data into an image data paradigm facilitates
the use of powerful image data processing techniques, including a
generalized logarithm (g-log) function to stabilize variance over
intensity, and the WSVD combination of wavelet packet transform and
denoising and SVD to clearly enhance separation of the truly changed
genes from background noise. Detection performance can be assessed using
a true false discovery rate (tFDR) computed for simulated gene expression
data, and comparing it to estimated FDR (eFDR) rates based on
permutations of the available data. Where a small number (N) of samples
in a group is involved, a pair of specific WSVD algorithms are employed
complementarily if N>5 and if N<6.