Kaplan-Meier curve of the groups according to the expression levels of genes (a)
, and of the groups defined by the four combinations of expression levels of (c)
, and (d)
in the lung cancer study. The groups of patients were determined according to the low-high expression status of the genes considered. Patients whose expression measurement was higher (resp. lower) than the median were assigned to the "highly expressed" (resp. "lowly expressed") group.