The Effects of Food Stamp and WIC Programs on Nutrient Intakes of Children

Year: 2001

Research Center: Department of Nutrition at the University of California, Davis

Investigator: Yen, Steven T.

Institution: University of Tennessee

Project Contact:
Steven T. Yen
University of Tennessee
Department of Agricultural Economics
308D Morgan Hall
Knoxville, TN 37996-4518
Phone: 865-974-7474
Fax: 865-974-4829


This study investigated factors determining participation in the Food Stamp Program (FSP) and the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), and the effects of these programs on nutrient intakes of small children. In previous studies, program participation was often investigated without consideration of the decisions on food and nutrition intakes. However, consumers typically make food choices from several commodities, and each food item typically contains multiple nutrients. Further, the decision to participate in the FSP and WIC is likely to be made simultaneously with the food and nutrient intake decisions. Statistical estimation procedures that ignore cross-equation correlation can cause loss of efficiency, and failure to accommodate simultaneity also leads to biases in empirical estimates.

This study addressed participation and effectiveness of the FSP and WIC in a multi-equation framework for nutrient intakes with endogenous FSP and WIC participation. The model considered is a multivariate generalization of the sample selection model and can also be viewed as a restricted form of switching regression for a system of equations.

In this study, the author examined (1) simultaneity of program (FSP and WIC) participation, food and nutrient intakes, and program participation and nutrition intakes, (2) effects of income and other explanatory variables on program participation, (3) effects of programs on nutrition intakes, and (4) effects of income and other explanatory variables on nutrient intakes. Nutrient intakes are expressed as a percentage of the recommended daily allowance reported in Federal dietary guidelines.

Empirical analysis was conducted for formula-fed infants and children, using data from the 1994-96 Continuing Survey of Food Intakes by Individuals and the 1998 supplemental Children’s Survey. The findings indicate that the decision to participate in the FSP and WIC, as well as nutrient intake decisions, are made simultaneously. WIC participation is found to increase the intakes of most nutrients, whereas the effects of FSP are mixed. Overall, participation in both programs increases the intakes of all nutrients except protein. The methodology developed in this study can be used in future studies of the effects of other food assistance programs, such as the National School Lunch Program, on food intakes, nutrient intakes, and other outcome variables.