The Women, Infants, and Children (WIC) Program is considered a crucial component of the social safety net in the United States, yet there is limited supporting evidence on the effects of WIC on the nutritional well-being and food security of infants and young children.  Two key identification problems have been especially difficult to address.  First, the decision to take up WIC is endogenous as households are not randomly assigned to the program; recipients are likely to differ from nonrecipients in unobserved ways (e.g., prior health) that are related to associated outcomes.  Second, survey respondents often fail to report receiving public assistance, and the existing literature has uncovered substantial degrees of systematic misclassification of WIC participation.  Using data from the National Health and Nutrition Examination Survey (NHANES), we apply recently developed partial identification methodologies to jointly account for these two identification problems in a single framework.  Under relatively weak assumptions, we find that WIC reduces the prevalence of child food insecurity by at least 5.5 percentage points and very low food security by at least 1.5 percentage points.

Keywords: Women, Infants, and Children (WIC) Program, food insecurity, partial identification, treatment effect, nonparametric bounds, nonclassical measurement error, classification error