Ensuring Confidentiality of Geocoded Health Data: Assessing Geographic Masking Strategies for Individual-Level Data

Figure 6

Example of geographic masking technique (i.e., random placement within a circle) using an additional spatial filter to constrain displacement. The red dot represents the original location; the yellow area represents all possible locations for the masked location; and the blue dot represents one possible masked location selected randomly. This filter can be used to avoid placement in areas where logically no population resides (such as water bodies or parks) or to limit displacement to a particular enumeration unit (such as the same census tract or postal code).