A Pilot Study of GPS Technology in Tracking Homeless Adults

Introduction: To date, geospatial studies of homeless populations have been limited to self-report data, calculation of distances from agency data, and non-continuous tracking through cell phone technology. These methods fail to capture movement patterns with sufficient continuity and precision to maximally inform effective service placement. The purpose of this study was to examine the feasibility of using GPS technology in a difficult-to-follow population.

Methods: Twenty homeless individuals selected from a homeless day center each carried a GPS tracking device to record their movements for one day. Participants completed a demographic questionnaire and pre-tracking and post-tracking surveys about planned and reported travels. GPS data were downloaded and exported for the creation of Google Earth spatial travel maps and to create an ArcView 9.3 database.

Results: After achieving successful deployment, 80% completion was obtained. Travel distances varied (.05-36 miles), on foot and by motor vehicle. No tracking devices were lost during deployment, although one was water-damaged in a shower. Challenges in conducting the study included battery problems (power, theft), signal loss, lengthy initial calibrations (up to 15 minutes), drift of satellite anchors to positions, and difficulties re-engaging with participants post deployment.

Conclusions: This study demonstrated the feasibility of using GPS technology to track continuous movements of the difficult-to-track homeless population. This work has clarified the need to integrate GPS and self-report data to maximize the precision of geospatial data. This study demonstrated the potential for GPS technology to improve service access and identify geospatial barriers to care beyond currently available methodologies.