The present invention aims at providing a visual display which is useful in roughly
understanding the state of groupings and changes, by comparing expression data
of genes from two experiments based on expression data of one sample common to
both experiments.
In order to compare data of expression levels obtained from different experiments
each using two types of samples, three types of expression levels are displayed
in three-dimension as mediated by the data of the common sample used in both experiments.
Specifically, expression level data for Samples A and B and expression level data
for Samples A and C are combined and converted into single three-dimensional data
and displayed as points inside a sphere. Alternatively, expression states of each
gene to Samples A, B and C are mapped on a sphere with respect to a ratio between
Sample A and Sample B and a ratio between Samples A and C, and displayed as distribution
on the surface of the sphere. A clustering analysis is performed based on the distributed
points inside or on the sphere, to visually understand the expression state of
genes for the three types of samples. In addition, the expression level data displayed
as points inside or on the sphere are linked as a line or a curve for each gene
or for each gene group resulting from the clustering analysis, to visually understand
the changes of expression states with time.