PCA of the grouped antidepressant data. Biplot of gene scores and treatment groups loadings according to the first two components of the PCA. The open circles represent the gene scores. The vectors represent the treatment groups (variable) loadings. The biplot enables the association of genes with the treatment groups. Genes labeled with numbers have test values above the 95% percentile of the permutation distribution; genes labeled with gene symbols have test values above the 99% percentile.
Landgrebe et al. Genome Biology 2002 3:research0019.1-research0019.11 doi:10.1186/gb-2002-3-4-research0019