Compare methods

	In-Store Food Availability Audit	Modified Retail Food Environment Index
Field	Food Agriculture Studies	Food Agriculture Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2007	2011
Originator	Food-environment field-audit tradition (general observational protocol; cf. Glanz, Saelens & colleagues' instruments)	U.S. Centers for Disease Control and Prevention (CDC), Division of Nutrition, Physical Activity and Obesity
Type	Structured observational field-audit pipeline	Spatial ratio index of healthy to all food retailers by census tract
Seminal source	Glanz, K., Sallis, J. F., Saelens, B. E., & Frank, L. D. (2007). Nutrition Environment Measures Survey in Stores (NEMS-S): Development and Evaluation. American Journal of Preventive Medicine, 32(4), 282-289.	Centers for Disease Control and Prevention (2011). Children's Food Environment State Indicator Report, 2011 — Census Tract Level State Maps of the Modified Retail Food Environment Index (mRFEI). Atlanta, GA: U.S. Department of Health and Human Services, CDC.
Aliases	Store Food Audit, Food Availability Audit, Retail Food Observation Protocol, In-Store Food Environment Audit	mRFEI, Modified Food Environment Index, CDC Retail Food Environment Index, Healthy Food Retailer Ratio
Related	4	4
Summary	An in-store food availability audit is a structured observational protocol in which a trained auditor physically visits a food outlet and records, against a predefined checklist, which foods are stocked, at what prices, and in what condition. It is the general field-audit method that underpins much food-environment research: rather than inferring access from business listings, the auditor walks the aisles and documents reality. The approach was crystallised by validated instruments such as Glanz, Saelens and colleagues' Nutrition Environment Measures Survey, but the audit logic — define an item list, sample outlets, train raters, observe systematically, and check reliability — is a reusable protocol that researchers adapt to corner stores, supermarkets, markets, pharmacies and informal vendors. The output is a direct, reproducible characterisation of what people can actually buy where they live.	The Modified Retail Food Environment Index (mRFEI) is a spatial measure, developed by the U.S. Centers for Disease Control and Prevention, that summarises the retail food environment of a small area as the percentage of healthy food retailers among all food retailers in that area. For each census tract, the CDC counted healthy retailers (supermarkets, larger grocery stores, supercenters and produce stores) and less-healthy retailers (fast-food restaurants, convenience and small grocery stores) from national business databases, then expressed the index as healthy divided by all, times 100. Released in the 2011 Children's Food Environment State Indicator Report with census-tract maps for every U.S. state, the mRFEI offers a scalable, secondary-data way to flag food deserts (no retailers) and food swamps (dominated by less-healthy outlets) and to study how the food landscape relates to diet and obesity.