Figure 1

Privacy-preserving histograms. Figures (A), (B) and (C) show the histograms of X (top rows) and Y (bottom rows) from datasets D1, D2 and D3 respectively. From left to right we demonstrate (i) the histograms of the actual variables; (ii) the histograms of the variables after suppressing any bins with less than three counts; (iii) the histograms of the variables after generalizing the variables into bins based on wider intervals and suppressing any bins with less than three counts; (iv) the histograms of the scaled centroids of each 3-nearest neighbours; (v) the histograms of the variables with added noise of variance equal to 6.25% of the true variance. Note that the vertical axis represents the frequency density which is the frequency of each bin divided by its width