Abstract
To overcome the challenge of obtaining accurate data on community food retail, we developed an innovative tool to automatically capture food retail data from Google Earth (GE). The proposed method is relevant to non-commercial use or scholarly purposes. We aimed to test the validity of web sources data for the assessment of community food retail environment by comparison to ground-truth observations (gold standard). A secondary aim was to test whether validity differs by type of food outlet and socioeconomic status (SES). The study area included a sample of 300 census tracts stratified by SES in two of the largest cities in Brazil, Rio de Janeiro and Belo Horizonte. The GE web service was used to develop a tool for automatic acquisition of food retail data through the generation of a regular grid of points. To test its validity, this data was compared with the ground-truth data. Compared to the 856 outlets identified in 285 census tracts by the ground-truth method, the GE interface identified 731 outlets. In both cities, the GE interface scored moderate to excellent compared to the ground-truth data across all of the validity measures: sensitivity, specificity, positive predictive value, negative predictive value and accuracy (ranging from 66.3 to 100%). The validity did not differ by SES strata. Supermarkets, convenience stores and restaurants yielded better results than other store types. To our knowledge, this research is the first to investigate using GE as a tool to capture community food retail data. Our results suggest that the GE interface could be used to measure the community food environment. Validity was satisfactory for different SES areas and types of outlets.
Highlights
The food retail environment is a component of the food environment
856 outlets were identified in the ground-truth data (445 in Rio de Janeiro and 411 in Belo Horizonte) in 285 census tracts, compared to 731 outlets in the Google Earth (GE) interface data (458 in Rio de Janeiro and 273 in Belo Horizonte)
While food outlets were more likely to be missing in Belo Horizonte, they were overestimated by GE in Rio de Janeiro (Fig. 2)
Summary
The food retail environment is a component of the food environment. Researchers, health professionals and policymakers are increasingly recognizing the role of the retail food environment in driving health behaviours and outcomes [1]. A scarcity of accurate retail environmental data remains a challenge for researchers around the world [2]. The lack of consistency and rigour in measuring food retail environments is believed to contribute to the inconsistent results of studies investigating the diet-food environment relationship [3, 4]. Poor data can lead to uncertainty, bias and reduced statistical power [5]. When stakeholders have inaccurate information about the food environment, their planning, policies and efforts to improve access to healthy food can be adversely affected [6]
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