imodality index has been implemented in an R package named as

lIndex. The discrimination between unimodal and bimodal

mplemented using a mixture model (R package mclust) for the

ndex values.

e gap maximisation test approach

maximisation test approach (GM) is another simple approach for

ression bimodality discovery [Al Watban and Yang, 2016]. The

a is to model the density of delta expressions. It is believed that

nce of the bimodality within a gene expression vector may cause

fast decaying Gamma density of the delta expressions of the gene.

density can be well-estimated, the expression bimodality can thus

iscovered.

(a) (b) (c)

he delta expression density of three randomly selected genes from the letrozole

Only 58 letrozole treatment expressions were used for this density estimation.

ines stand for the fitted Gamma densities. (a) The gene ZMIZ2. (b) The gene

c) The gene ARHGAP2B.

e 6.32 shows the estimated densities as well as their Gamma

rves of the delta expressions of three randomly selected genes

data set in which the letrozole drug was used to treat breast cancer

6) [Miller, et al., 20017; Miller, et al., 2010]. It can be seen that

ZMIZ2 shows a sharp decaying Gamma density while the gene