On the wrong side of the tracts? Evaluating the accuracy of geocoding in public health research

Abstract

Objectives. This study sought to determine the accuracy of geocoding for public health databases. Methods. A test file of 70 addresses, 50 of which involved errors, was generated, and the file was geocoded to the census tract and block group levels by 4 commercial geocoding firms. Also, the "real world" accuracy of the best-performing firm was evaluated. Results. Accuracy rotes in regard to geocoding of the test file ranged from 44% (95% confidence interval [CI] = 32%, 56%) to 84% (95% CI=73%, 92%). The geocoding firm identified as having the best accuracy rate correctly geocoded 96% of the addresses obtained from the public health databases. Conclusions. Public health studies involving geocoded databases should evaluate and report on methods used to verify accuracy.