Figure 2.

Estimating expected k-anonymity. Using the data set standard deviation of the distance each patient is moved in the anonymization, σ, an estimate of achieved k-anonymity is calculated, assuming no other external knowledge of specific patient information. The local population density (people/km²) is multiplied by each area (km²) and then multiplied by the probability that the patient would have been in that area, from the Gaussian probability distribution function.