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OJB®
Online
Journal of Bioinformatics ©
Volume 7 (2):90-100, 2006
Muhammad MA1, Neuhäuser
M1, 2
1: Institute for Medical
Informatics, Biometry and Epidemiology,
ABSTRACT
Muhammad MA, Neuhäuser M, A
computer-intensive method to analyse microarray experiments with a very small
number of replications in case of heteroscedasticity, Online J Bioinformatics 7
(2):90-100, 2006. In this paper different
tests for the nonparametric Behrens-Fisher problem are investigated, i.e.
detecting differences in mean gene expression levels is of primary interest;
the tests should not be sensitive for possible pure differences in variability.
Beside the rank Welch test and the Brunner-Munzel
test a modification of Cliff’s method is studied. In contrast to the original
method, the proposed modification has an advantage in case of a very small
number of replications (sample size). All tests are performed as bootstrap
tests and are applied to both real microarray data as
well as simulated data. It is
demonstrated that the tests can be applied in case of sample sizes as small as
five per group. The results indicate that the rank Welch test is the preferred
test.
Keywords: Identification of differentially expressed genes;
Bootstrap test; Rank Welch test; Brunner-Munzel test,
Cliff’s method