Locational uncertainty in georeferencing public health datasets

The assignment of locational attributes to a study subject in epidemiologic analyses is commonly referred to as georeferencing. When georeferencing st udy subjects to a point location using their residential street address, mo st researchers rely on the street centerline data model. This study assesse d the potential locational bias introduced using street centerline data. It also evaluated georeferencing effects on a location-dependent, exposure as sessment process. For comparison purposes, subjects were georeferenced to t he center of their residential parcel of land using digitized parcel maps, A total of 10,026 study subjects residing in Jefferson County, Alabama were georeferenced using both street centerline and residential parcel methods. The mean nondirectional, linear distance between points georeferenced usin g both methods was 246 ft with a range of 11 to 13,260 ft. Correlation coef ficients comparing differences in exposure estimates were generated for all 10,026 subjects. Coefficients increased as the geographic areas of analysi s around study subjects increased, indicating the influence of nondifferent ial exposure misclassification.