It can be extremely useful to inspect the of each sample and sample group at each of the differentially expressed genes from all of the differential comparisons, using a heatmap. This allows visual identification of how the various groups of genes relate to each other, and also the global patterns of differential expression over the experiment. In addition the genes have been clustered. In simple terms, grouped by the similarity of their expression profiles. This often highlights any sub−patterns within the data. Finally, in order to focus on the pattern of expression, rather than which gene is generically more highly expressed than any other gene, etc, the data has been row standardised with a z−score. This is often considered as a keystone plot in any Mde analysis.
