Doctoral Dissertation Research Christian: Using Geospatial Technologies to Characterize Relationships Between Travel Behavior, Food Availability and Health.

PROJECT SUMMARY TITLE: Doctoral dissertation research: Applying time-geographic concepts and GPS technology to characterize the accessibility of retail food opportunities The doctoral dissertation research I propose here will address the analysis of spatialtemporal data for describing the accessibility of retail food opportunities, including supermarkets, groceries, convenience stores, and restaurants. Many spatial epidemiologic studies have noted statistical associations between the accessibility of these food sources and individual characteristics such as weight, socioeconomic status (SES), and race/ethnicity. In these studies, researchers have typically employed accessibility measures based on residential location, and have sometimes relied on areal units (e.g., census tracts, zip codes) for analysis. For example, distances from subjects' homes to the nearest supermarket might be examined for statistical association with SES. Similarly, researchers have defined the accessibility of fast food opportunities at the census tract level to explore an association with obesity, while controlling for individual factors (e.g., SES, race/ethnicity). These residence-based models implicitly assume individuals usually purchase food from retail food locations nearest to their residence. There is, however, conflicting evidence regarding this assumption, suggesting reliance on residence-based models could result in ecological fallacy. Thus, I will develop new techniques to describe the accessibility of retail food locations at the individual-level, and explore their utility for spatial epidemiologic investigations related to public health and nutrition. InteUectual Merit: This study will investigate (1) an innovative approach for describing individi:1ats'access to retail food opportunities, and (2) the novel use of global positioning system (GPS) technology to determine individual accessibility to food opportunities. By incorporating locational data on where participants work, recreate, attend school, or engage in other activities, I will implement an individual activity-based model of food accessibility influenced by concepts from time-geography. Thus, the accessibility of retail food locations for participants will be based on their daily activity patterns in urban space-their activity space. I will capture activity-travel data using small GPS data loggers before analysis in a geographic information system (GIS). To date, these devices have not been deployed in research investigating the accessibility of retail food resources. Broader Impacts of Proposed Research: Broad dissemination to enhance scientific and technological understanding- This interdisciplinary research applies spatial-temporal analytic concepts from geography to develop techniques for addressing health-related issues. Thus, study findings will be presented at conferences and in journals related to both geography and public health. Advance discovery and understanding while promoting teaching, training, and learning- To facilitate participant enrollment and data collection, I will employ both graduate and advanced undergraduate students. In working on this research, they will gain valuable experience working with human subjects and GPS and GIS technologies. Benefits to society-Investigating daily travel patterns and how they relate to the accessibility of retail food opportunities will provide valuable insight for policy formulation by multiple government agencies, including those related to public health, transportation, and planning.