eligibles were more ambiguous and small in size. Using a 6-month certification period for children instead of the 12-month certification period used currently in estimating eligibility results in an undercount of children of 4 percent if annual income is used, but in a 5 percent overcount if monthly income is used. The use of alternative definitions of the economic unit results in very little change in the total number of estimated eligibles, and the direction of the effect depends on the base with which estimates are being compared. Finally, the panel considered current methods for estimating the percentage of income eligible persons who are at nutritional risk and concluded that these estimates should be reexamined with more recent data.
Considering these findings in total, the panel concludes that current estimation methods result in a substantial understatement of eligible persons.
Conclusion: The panel concludes that current methods used to estimate eligibility for WIC substantially underestimate the number of people who are eligible.
The underestimation of eligibility implies that coverage rates are overstated. From the simulation results presented here, the number of infants estimated to be eligible for WIC is underestimated by a total of 54 percent—considering the undercount of infants in the CPS, adjunctive eligibility, and the use of monthly income instead of annual income. The latest coverage rate available for infants is 130.4 percent in 1999. If this rate is recalculated using the increased estimate of eligible infants, the coverage rate falls to 84.7 percent. Presumably the coverage rates of pregnant and postpartum women would also fall similarly. For children, the total underestimation of eligible people is 25 percent (considering an overcount of children in the CPS, adjunctive eligibility, the use of monthly instead of annual income, and a 6-month certification period). The 1999 coverage rate for children was 76.0 percent; when this rate is recalculated with the larger estimate of eligible children, then the coverage rate falls to 60.8 percent. Thus, coverage rates based on the panel’s estimates of eligibility would fall considerably if these estimates pass further scrutiny.
It is important to note that the underestimation of eligible people and subsequent overestimation of coverage rates do not necessarily mean that no ineligible persons are participating in WIC. The panel does not explore this possibility, for it is not part of our charge. We do note that the USDA has recently conducted a WIC income verification study and plans to release the results in late 2001.