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

对美国肥胖症流行的日益关注促使人们对病因和干预措施进行了探索。最近的几项流行病学研究指出，各种类型的零售食品来源（如超市、杂货店、便利店和所有类型的餐馆）的空间可达性与个体特征（如体重、社会经济地位和种族/民族）之间存在统计学关联。这些研究通常使用零售食品来源与个人住宅的接近程度作为可达性的衡量标准，并且通常依赖于面积单位，如人口普查区和邮政编码。然而，以这种方式评估可达性可能导致生态谬误。由于大多数人每天都在其人口普查区之外旅行，因此居住在同一地区的个人可获得的零售食品来源的数量和类型可能会有很大差异。在肯塔基大学地理系教授Gary Shannon的指导下，博士生Jay Christian将开发一个基于个人活动和旅行模式（他们的活动空间）的可达性模型，而不仅仅是基于居住地点。研究人员以前使用旅行日记来研究活动和旅行行为，但这需要研究参与者的很大程度的承诺，并且容易出现回忆错误和其他不准确的地方。本研究将探索使用全球定位系统（GPS）来识别参与者的活动空间，并使用地理信息系统（GIS）来评估位于这些空间内的零售食品来源的数量和类型。因此，它将产生一种不依赖于面积单位，也不需要使用旅行日记的个人零售食品可及性的替代措施。这项研究将在肯塔基州列克星敦的一个人口普查区招募200名居民，让他们携带GPS数据记录仪，在两个工作日内跟踪他们的活动。参与者还将完成关于他们的社会经济、人口统计、生物特征和饮食特征的调查，并评估他们在GPS数据记录期间购买食物的地点。报告的食品购买地点将根据来自GPS数据记录器的数据进行登记。利用这些数据，本研究将评估一个新的基于活动的可及性模型与以前的模型相比的相对效用，并探索可及性、食品购买和饮食之间的联系。通过研究个人日常运动对获取食物的影响，这项研究将有助于科学文献解决美国肥胖流行的原因和潜在解决方案。因此，它将为多个政府机构的政策制定提供见解，包括与公共卫生、交通和规划有关的机构。

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.