Visualization of clustered microarray data and clinical data. The gene expression data (primary data) is displayed by colored squares, each one representing a specific gene and sample. A green square represents an up-regulation, a black square an unchanged expression and a red square a down-regulation compared to reference. The microarray data is clustered both with respect to subjects and genes (a). The hierarchical clustering result is displayed as a tree on the top and on the left side of the data (b and c). The rows and columns are permuted according to the leaves of the cluster trees. Clinical data (secondary data) available for the subjects is displayed between the top cluster tree and the microarray data (d).