The impact of geocoding method on the positional accuracy of residential burglaries reported to police

Abstract

Purpose

The purpose of this paper is to better understand the variability in burglary geocoding positional accuracy between United States Census Topologically Integrated Geographic Encoding and Referencing (TIGER)-based street geocoding and results produced using reference data made publicly available by Google.

Design/methodology/approach

This research compares the Euclidian distance between ground-truthed burglaries and results produced using two different geocoding reference data sets: TIGER-based street geocoding and publicly available data within Google Earth. T-tests and z-tests are used to discern whether positional errors are statistically significant.

Findings

Both within suburban and urban jurisdictions, Google outperformed street geocoding in terms of positional accuracy. Positional errors on average were 1/4th as large for Google in a suburban setting and 1/5th as large in an urban setting compared to street geocoding.

Practical implications

Police departments that are relying on street geocoding techniques may achieve improved spatial precision by using Google’s reference data if they contain parcel-level information. Moreover, relying on less precise spatial referencing methods may place burglaries in locations where the events do not actually occur or cluster.

Originality/value

This is the first analysis of law enforcement data to examine the positional accuracy of geocoded offense data using Google Earth compared to the commonly used street geocoding method of interpolation.

Citation

Mazeika, D. and Summerton, D. (2017), "The impact of geocoding method on the positional accuracy of residential burglaries reported to police", Policing: An International Journal, Vol. 40 No. 2, pp. 459-470. https://doi.org/10.1108/PIJPSM-03-2016-0048