Figure 4

Privacy-preserving box plots. Figures (A), (B) and (C) show the box plots of X and Y from datasets D1, D2 and D3 respectively. From left to right we demonstrate: (i) the actual box plots of the variables; (ii) the data are aggregated in a 30 by 30 density grid matrix, any grids with density less than three counts are suppressed, and the box plots for the observations that are exist in the remaining grids are displayed; (iii) the data are aggregated in a 15 by 15 density grid matrix (i.e. further generalization), any grids with density less than three counts are suppressed, and the box plots for the observations that are exist in the remaining grids are displayed; (iv) the box plots of the scaled centroids of each 3-nearest neighbours obtained by deterministic anonymization; (v) the box plots of noisy variables obtained by addition of random stochastic noise in each variable, of variance equal to 6.25% of the true variability