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探索原因和干预措施。最近的几项流行病学研究指出，超市、杂货店、便利店和所有类型的餐馆等各类零售食品来源的空间可及性与体重、社会经济地位和种族/民族等个人特征之间存在统计关系。这些研究通常使用零售食品来源与个人住所的接近程度作为可获得性的衡量标准，并往往依赖于人口普查区域和邮政编码等面积单位。然而，以这种方式评估可获得性可能会导致生态谬误。由于大多数人每天都在人口普查区域之外旅行，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的差异。在肯塔基大学地理系加里·香农教授的指导下，博士生杰伊·克里斯蒂安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，而不仅仅是居住位置。研究人员以前曾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做出很大程度的承诺，而且容易出现回忆错误和其他不准确的情况。这项研究将探索使用全球定位系统(GPS)来确定参与者的活动空间，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，它将产生一种衡量个人零售食品可及性的替代措施，不依赖于面积单位，也不需要使用旅行日记。这项研究将招募肯塔基州列克星敦一个人口普查区域的200名居民携带GPS数据记录器，在两个工作日内跟踪他们的行动。参与者还将完成关于他们的社会经济、人口统计、生物统计和饮食特征的调查，并评估他们在GPS数据记录期间在哪里购买食品。报告的食品购买地点将根据GPS数据记录器获得的数据进行登记。使用这些数据，这项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、食物购买和饮食之间的联系。通过解决个人日常运动对他们获得食物的影响，这项研究将有助于撰写科学文献，探讨美国肥胖症流行的原因和潜在的解决方案。因此，它将为多个政府机构的政策制定提供洞察力，包括与公共卫生、交通和规划相关的政策。

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.