Wikipedia
In data analysis involving geographical locations, geo-imputation or geographical imputation methods are steps taken to replace missing values for exact locations with approximate locations derived from associated data. They assign a reasonable location or geographic based attribute (e.g., census tract) to a person by using both the demographic characteristics of the person and the population characteristics from a larger geographic aggregate area in which the person was geocoded (e.g., postal delivery area or county). For example if a person's census tract was known and no other address information was available then geo-imputation methods could be used to probabilistically assign that person to a smaller geographic area, such as a census block group.