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

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Growing concern related to the epidemic of obesity in the U.S. has prompted exploration of causal factors and interventions. Several recent epidemiologic studies have noted statistical associations between the spatial accessibility of various types of retail food sources such as supermarkets, groceries, convenience stores, and restaurants of all types, and individual characteristics such as weight, socioeconomic status, and race/ethnicity. These studies typically use the proximity of retail food sources to individuals' residences as the measure of accessibility, and often rely on areal units, such as census tracts and zip codes. Assessing accessibility in this manner, however, could result in ecological fallacy. Since most people travel outside of their census tract on a daily basis, the number and types of retail food sources available to individuals residing in the same area could vary widely. Doctoral student Jay Christian under the guidance of Professor Gary Shannon in the Department of Geography at University of Kentucky will develop a model of accessibility based upon individuals' activity and travel patterns (their activity space) rather than residential location alone. Researchers previously have used travel diaries to study activity and travel behavior, but these require a significant degree of commitment from study participants, and are prone to recall error and other inaccuracies. This study will explore the use of the global positioning system (GPS) to identify participants' activity spaces, and employ a geographic information system (GIS) to assess the number and types of retail food sources located within these spaces. It will thus produce an alternative measure of individual retail food accessibility that does not rely on areal units, nor require the use of travel diaries. This study will recruit 200 residents of a single census tract in Lexington, Kentucky to carry GPS data loggers to track their movements for two workdays. Participants will also complete surveys regarding their socioeconomic, demographic, biometric, and dietary characteristics, and to assess where they purchased food during the GPS data logging period. Reported food purchase locations will be registered against data derived from the GPS data loggers. Using these data, this study will assess the relative utility of a new activity-based model of accessibility compared to previous models, and explore the link between accessibility, food purchasing, and diet.By addressing the effect of individuals' daily movements on their access to food, this research will contribute to scientific literature addressing the causes of, and potential solutions to, the obesity epidemic in the United States. As such, it will provide insight for policy formulation by multiple government agencies, including those related to public health, transportation, and planning.