Figure 2

Privacy-preserving scatter plots. Figures (A), (B) and (C) show the scatter plots of X and Y from datasets D1, D2 and D3 respectively. From left to right we demonstrate: (i) the scatter plots of the actual variables; (ii) the scatter plots of the data aggregated in a 30 by 30 density grid matrix and suppressing any grids with density less than three counts; (iii) the scatter plots of the data aggregated in a 15 by 15 density grid matrix (i.e. additional generalization) and suppressing any grids with density less than three counts; (iv) the scatter plots of the scaled centroids of each 3-nearest neighbours obtained by deterministic anonymization; (v) the scatter plots of noisy X and Y obtained by addition of random stochastic noise in each variable, of variance equal to 6.25% of the true variability. Notes: Each data point in panels (ii)–(iii) is located at the center of the grid and its size corresponds to the number of observations in the grid. The grids are shown with transparent lines. Panels (ii)–(iii) in Figure (A) include the actual linear trend line of X and Y (red) and the weighted linear trend line of the k-anonymized data (grey). Panels (iv)–(v) in Figure (A) include the linear trend lines of actual (red) and anonymized (grey) X and Y variables. The black dots in panels (iv) indicate the positions where more than one centroids are identically placed