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Variation in low food access areas due to data source inaccuracies
Xiaoguang Ma1, Sarah E Battersby2, Bethany A Bell3
1Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA.
Applied Geography (Sevenoaks, England)
|December 25, 2013
Summary
Data inaccuracies in commercial datasets can affect food desert designations. While acceptable for large-scale surveillance, local efforts to improve food access require field data verification.
Area of Science:
- Public Health
- Geospatial Analysis
- Food Access Studies
Background:
- Spatial measures identify "food deserts" using commercial data on food retailers.
- The impact of data inaccuracies on "food desert" designations is not well understood.
Purpose of the Study:
- To assess how data inaccuracies in secondary sources influence "food desert" and "non-healthier food retail tract" designations.
- To compare the accuracy of two common food access measures using different data sources.
Main Methods:
- Replicated U.S. Department of Agriculture Economic Research Service (USDA ERS) "food desert" and Centers for Disease Control and Prevention (CDC) "non-healthier food retail tract" measures.
- Utilized two secondary data sources (InfoUSA, Dun & Bradstreet) and reference data from an eight-county field census in South Carolina (169 Census tracts).
- Calculated accuracy statistics including concordance, sensitivity, and positive predictive value (PPV).
Main Results:
- For the USDA ERS "food desert" measure, secondary data showed 94% concordance but low sensitivity (50-65%) and PPV (60-64%).
- For the CDC "non-healthier food retail tract" measure, secondary data demonstrated higher concordance (88-91%), sensitivity (80-86%), and PPV (78-82%).
Conclusions:
- Inaccuracies in secondary data sources for identifying low food access areas may be acceptable for large-scale public health surveillance.
- Verification with field data is recommended for local community initiatives focused on identifying and improving food access.
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