Relation between the abundance or the fold change of a metabolite and its rank after data pretreatment. The highest ranked metabolite after data pretreatment, based on its cumulative contributions on the loadings of the first three PCs, has position 1 on the X-axis. The metabolite that is ranked at position 1 on the Y-axis has either the highest fold change in concentration (largest standard deviation of the peak area over all the experiments in the clean data (O)); or is most abundant (largest mean concentration (□)) in the clean data.
van den Berg et al. BMC Genomics 2006 7:142 doi:10.1186/1471-2164-7-142