  Although a generalized spike population model has been actively studied in
random matrix theory, its application to real data has been rarely explored. We
find that most methods for determining the number of spikes based on the
Johnstone's spike population model choose far too many spikes in RNA-seq gene
expression data or often fail to determine the number of spikes by indicating
that all components are spikes. In this paper, we propose a new algorithm for
the estimation of the number of spikes based on a generalized spike population
model. Also, we suggest a new noise model for RNA-seq data based on population
spectral distribution ideas, which provides a biologically reasonable number of
spikes using the proposed algorithm. Furthermore, we propose a graphical tool
for assessing the performance of the underlying noise model.
