11/24/2014
Today's Seminar - Nese Yildiz, 11/24/2014
Econometrics
Nese Yildiz
University of Rochester
Diagnostic Tests of Selection on Observables Assumption: The Case of WIC
Abstract: Women, Infants, and Children (WIC) is a federally funded program that \provides nutritious foods, nutrition education (including breastfeeding promotion and support), and referrals to health and other social services to participants at no charge. WIC serves low-income pregnant, postpartum and breastfeeding women, and infants and children up to age 5 who are at nutrition risk... Congress appropriated 6:522 billion for WIC in FY 2013." (Source: http://www.fns.usda.gov/sites/default/_les/WIC-Fact-Sheet.pdf, date: 4/24/14, 11:06am.) While the goals of WIC are clear, there does not seem to be a consensus about the effects of WIC. The main source of disagreement is the possibility that the participation into the program may not be random, and whether the controls in a given study do a good job eliminating the effects of this possible non-random selection and, hence, estimate the true effect of WIC participation. In this paper we present diagnostic tests for selection on observables assumption. Our diagnostic tests are based on the presence of a variable W among our controls that has a known bunching point (we normalize this point to be 0; in our example, W will denote number of ci******es smoked during pregnancy, which is constrained to be non-negative), but is otherwise continuously distributed. This set up was first exploited by Caetano(2012) to test exogeneity of smoking during pregnancy (same W variable we are considering) in considering the effect of smoking during pregnancy on baby's birthweight. She found that smoking during pregnancy is indeed endogenous, even in a model that includes a rich set of other controls. Caetano's test, however, cannot be applied to test exogeneity of a discrete covariate, which is the focus of this paper. We demonstrate our diagnostic tests using birth certificate data, which covers more than 80% of all births in the U.S. from 2010 - 2012 and contains a rich, detailed set of parental and pregnancy covariates, to study the impact of the Supplemental Program for Women Infants and Children (WIC) on birth outcomes.
Monday, November 24, 2014 • 3:30 PM - 5:00 PM • BRB 1.118