The goal of this study was to provide tabulations of transaction data from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) for six states across 12 months.
WIC offers supplemental, nutritious food intended to improve the health of low-income women and children at nutritional risk. The program is administered by state WIC agencies, some of which issue benefits through electronic benefit transfer (EBT) cards. EBT transaction data can be used to provide a snapshot of the foods that WIC participants purchase with their benefits.
Insight used raw EBT transaction data from the WIC Indicators of High Risk Vendors Study to produce cleaned public and internal use datasets, a set of 72 tables summarizing WIC benefit purchases for 6 states across the 12-month study period, and a final table encompassing these purchases for all 6 states across the study period. These tables were requested by an expert committee formed to conduct a review of WIC food packages and coordinated by the National Academies’ Institute of Medicine. The tables provide detailed data on the quantities and types of food that WIC participants purchase with their benefits.
As a first step, Insight standardized the data, which were produced by six different state EBT systems, to ensure that all transactions for similar foods were reported in the same way. For example, some milk transactions were reported in ounces and others were reported in gallons; the data were standardized so all milk transactions were reported in gallons. Next, Insight cleaned the data by removing records for transactions other than purchases and records that contained data that could not be interpreted.
The standardized, cleaned data were compiled into an internal use dataset and a public use dataset. To maintain participant and vendor confidentiality, all identifying variables (household ID, vendor ID, state, etc.) were removed from the public use dataset. Additionally, all transactions for infant formula and medical foods were removed since those records contained specific brand information.
All data standardization, cleaning, and tabulation were conducted in SAS. The summary tables were presented in Microsoft Excel.
Data Cleaning and Editing; Data Analysis and Tabulation
- Public use and internal use datasets (March 2016)
- Set of 73 tables (April 2016)
- Briefing on processes that were used for analyzing the data