A Comprehensive Assessment and Evaluation of the Digital Geospatial Data Sources Used in the Study of Food Deserts and Food Swamps

A Case Study in North Carolina

Abstract

Health outcomes due to poor diet are the result of many interrelated tangible and intangible factors. Differential access to food sources, both healthy and unhealthy, is one of these quantifiable factors that can be measured across space and place. Geospatial tools such as GIS (Geographic Information Systems) serve as a popular technology to assess and evaluate spatial dimensions of the food environment. For an eleven-county study area in Southeastern North Carolina, more than 2,400 points serve as potential food sources used in GIS analysis. However, little work has been done to test the accuracy and reliability of these data which serve as food sources. In this study, we developed a framework to assess and evaluate various forms of data accuracy (horizontal, attribute and temporal) and completeness of these data using comprehensive Quality Assurance/Quality Control (QA/QC) techniques. We found 77.5% of points were correct at the time of field testing. However, in exploring differences using between accuracies of various cohorts of these data sources, we found the accuracy for rural food sources to be less than urban counterparts at a 95% confidence. This can have a profound impact on the digital representation of food-needy regions calculated using GIS techniques and those regions that are truly food-needy.