Open Access Research

Evidence for validity of five secondary data sources for enumerating retail food outlets in seven American Indian Communities in North Carolina

Sheila E Fleischhacker1*, Daniel A Rodriguez2, Kelly R Evenson3, Amanda Henley4, Ziya Gizlice5, Dolly Soto6 and Gowri Ramachandran7

Author Affiliations

1 Senior Public Health & Science Policy Advisor, NIH Division of Nutrition Research Coordination, National Institutes of Health, US Department of Health and Human Services, Two Democracy Plaza, Room 635, 6707 Democracy Boulevard, MSC 5461, Bethesda, MD, 20892-5461, USA

2 Department of City and Regional Planning in the College of Arts and Sciences, 319 New East, Chapel Hill, NC, 27514, USA

3 Department of Epidemiology in the Gillings School of Global Public Health, Center for Health Promotion and Disease Prevention, Bank of America Center, 137 East Franklin St, Suite 306, CB # 8050, Chapel Hill, NC, 27514, USA

4 Geographic Information Systems Librarian, Reference Department in the Walter Royal Davis Library, 208 Raleigh St CB #3900, Chapel Hill, NC, 27514, USA

5 Director, Biostatistical Support Unit, Center for Health Promotion and Disease Prevention, 1700 Martin Luther King Jr. Blvd, CB# 7426, Chapel Hill, NC, 27599-7426, USA

6 Spatial Data Analyst, Center for Health Promotion and Disease Prevention, 319 New East, Chapel Hill, NC, 27514, USA

7 Healthy Eating Research Assistant, Center for Health Promotion and Disease Prevention, 1700 Martin Luther King Jr. Blvd, CB# 7426, Chapel Hill, NC, 27599-7426, USA

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International Journal of Behavioral Nutrition and Physical Activity 2012, 9:137  doi:10.1186/1479-5868-9-137

Published: 22 November 2012

Abstract

Background

Most studies on the local food environment have used secondary sources to describe the food environment, such as government food registries or commercial listings (e.g., Reference USA). Most of the studies exploring evidence for validity of secondary retail food data have used on-site verification and have not conducted analysis by data source (e.g., sensitivity of Reference USA) or by food outlet type (e.g., sensitivity of Reference USA for convenience stores). Few studies have explored the food environment in American Indian communities. To advance the science on measuring the food environment, we conducted direct, on-site observations of a wide range of food outlets in multiple American Indian communities, without a list guiding the field observations, and then compared our findings to several types of secondary data.

Methods

Food outlets located within seven State Designated Tribal Statistical Areas in North Carolina (NC) were gathered from online Yellow Pages, Reference USA, Dun & Bradstreet, local health departments, and the NC Department of Agriculture and Consumer Services. All TIGER/Line 2009 roads (>1,500 miles) were driven in six of the more rural tribal areas and, for the largest tribe, all roads in two of its cities were driven. Sensitivity, positive predictive value, concordance, and kappa statistics were calculated to compare secondary data sources to primary data.

Results

699 food outlets were identified during primary data collection. Match rate for primary data and secondary data differed by type of food outlet observed, with the highest match rates found for grocery stores (97%), general merchandise stores (96%), and restaurants (91%). Reference USA exhibited almost perfect sensitivity (0.89). Local health department data had substantial sensitivity (0.66) and was almost perfect when focusing only on restaurants (0.91). Positive predictive value was substantial for Reference USA (0.67) and moderate for local health department data (0.49). Evidence for validity was comparatively lower for Dun & Bradstreet, online Yellow Pages, and the NC Department of Agriculture.

Conclusions

Secondary data sources both over- and under-represented the food environment; they were particularly problematic for identifying convenience stores and specialty markets. More attention is needed to improve the validity of existing data sources, especially for rural local food environments.

Keywords:
Food environment; Measurement; Ground-truth; Secondary data; Validity; American Indian; Rurality; Global Positioning Systems (GPS); Geographic Information Systems (GIS)