Contribution of each constraint on the scores of the inflammatory factor (H3N2 challenge data). The five black colored pixels of the heatmaps indicate samples that were not assayed. Note that when only the sum-to-one constraint is applied, non-negativity is not guaranteed. However, for this dataset the sum-to-one factor scores turn out to take on non-negative values for the inflammatory factor (but not for the other factors).
Bazot et al. BMC Bioinformatics 2013 14:99 doi:10.1186/1471-2105-14-99