Estimating Eligibility and Participation for the WIC Program Final Report (2003) / Chapter Skim
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9. Options for Estimating Eligibility and Participation
9. Options for Estimating Eligibility and Participation
Pages 133-158
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From page 133... ...
ALTERNATIVE STRATEGIES FOR PREDICTING ELIGIBILITY Estimating the number of eligible individuals is central to prediction of the number of WIC participants. The estimates are needed to make budget requests and to calculate coverage rates.
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From page 134... ...
As Chapter 5 documented, the use of annual income instead of the conceptually more appropriate monthly income results in substantial underestimation of the numbers of eligible infants and children. A second disadvantage of the CPS is that it is impossible to identify, even indirectly, women who are pregnant.
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From page 135... ...
The next row, labeled "Using reported enrollment," continues to use the current USDA methodology but also counts as eligible any infant or child who reported enrollment in TANF, food stamps, or Medicaid. The use of reported enrollment in means-tested programs provides a direct method to identify WIC eligible infants and children who are adjunctively eligible.
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From page 136... ...
The row labeled "TRIM imputed CPS" in Table 9-1 reports the number of infants and children estimated to be eligible from CPS data that have imputed monthly income created by the TRIM model. The next row in the table, labeled "Multiplier," contains the ratio of the eligibility estimates based on the TRIM model's imputed monthly income relative to the CPSbased estimate using annual income plus those who report participation in means-tested programs (row labeled "Using reported enrollment".
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From page 137... ...
The stability and accuracy of these two multipliers would need to be assessed periodically.5 As discussed in Chapter 5, the SIPP data provide a more reliable source of information on monthly income, and hence the SIPP data would be a preferable data source to construct a multiplier to be applied to the base CPS estimates of income eligibility estimated from annual income and reported enrollment in means-tested programs.6 If SIPP is used to construct the multiplier, it is important that estimates appropriately account for WIC certification periods and include those infants and children who would be eligible based on their annual income and reported participation in meanstested programs. Because the panel had only two years of SIPP data with which to construct a multiplier, its stability could not be examined.
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From page 138... ...
Furthermore, the multiplier could also lead to inaccuracies in estimation if rules for means-tested programs, especially Medicaid, change. In the case of pregnant women, the proposed CPS option partially accounts for the differences in income prior to the birth of the child and during the postpartum period.
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From page 139... ...
Furthermore, the method implicitly assumes that the multiplier for income variability ancl for acljunctive eligibility for infants applies uniformly to the variability ancl acljunctive eligibility of pregnant ancl postpartum women (e.g., the effects of income variability on estimates of eligible infants is the same as the effects of income variability on eligibility estimates for pregnant ancl postpartum women)
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From page 141... ...
In particular, errors in the imputation process could assign participation to too many or too few individuals with incomes over 185 percent of federal poverty guidelines. If this is the case, the imputation process will create biases in the estimates of the number of eligible individuals.
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From page 143... ...
Second, using monthly income instead of annual income requires more data in order to accurately model certification periods. For example, in
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From page 144... ...
population by age, race, and gender. Comparison of Options Table 9-2 presents estimates of the number of infants, children, and pregnant women who are eligible for WIC and coverage rates for these groups computed by using the current USDA methodology and the panel's proposed methodologies for CPS and SIPP options.9 We focus on the years 9We have chosen not to present results for breastfeeding and postpartum women since we do not make specific recommendations pertaining to the proportional adjustment factors to be used for breastfeeding rates less than 6 months and greater than 6 months.
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From page 145... ...
Coverage rate Pregnant Women 9,383 9,039 41% 41% USDA methodology Eligibility (in 1,000) 1,202 1,232 1,196 1,139 1,102 1,085 Coverage rate 67% 66% 69% 74% 78% 78% CPS option estimates Eligibility (in 1,000)
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From page 146... ...
For children, the CPS option results in a 15-percent increase in eligibility estimates over estimates based on the current methodology, while the SIPP option results in a 38-percent increase in eligibility estimates for 1997. In 1998, the CPS option results in a 19-percent increase in the number of infants estimated to be eligible for WIC, while the SIPP option results in a 42-percent increase in the number of infants estimated to be eligible.
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From page 147... ...
If waiting lists for the WIC program, which would deny eligible individuals from receiving benefits, have not occurred, then one would be tempted to conclude that the funding had been adequate to meet the congressional desire to fully fund WIC.10 If the absence of waiting lists indicates that full funding has been achieved, any future changes in the funding level of the program would reflect anticipated changes in the number of individuals eligible for WIC or changes in the rate by which individuals chose to participate. Concluding that full-funding levels are achieved if waiting lists are not needed may not be appropriate.
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From page 148... ...
The next step is to project forward the number of eligible individuals from 1999 to 2003.11 Finally, USDA would explicitly make a judgment about an appropriate participation rate among eligible individuals, which is then the policy goal for the program in 2003. In setting these goals, USDA should take into account current coverage rates of the various groups and the likelihood that changes in administrative practices can inIIHistorically, USDA has assumed that there is no change in the number of eligible individuals over the four-year period.
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From page 149... ...
For the time being, let us assume that this 80 percent participation rate was actually the policy goal for the program that is, the goal was to allocate funds to serve 80 percent of those who were eligible.13 Because the estimated coverage rate exceeds 12Empirical studies on the decision to participate in WIC similar to the ones reported in Chapter 8 or perhaps a study that interviews people eligible for WIC who chose not to participate could inform these types of decisions to be made by USDA and the Congress. 13One interpretation of the USDA assumption that 80 percent of eligible individuals will participate is that the assumption was more of a statement of a policy goal than a "behavioral" prediction about actual participation in the program.
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From page 150... ...
However, since the USDA implicitly assumes that the number of eligible infants does not change over the forecasting period (from 1999 to 2003) , the above expression can be rewritten as FFPR x E2003 = CR1sss x E2003 = E x E1999 P1999 999 14Assume that the true change in the number of eligible infants is ~ while the prediction of the change based on a forecasting model is D = ~ + £ where £ is the error in the forecast and its expected value is O and variance is O2.
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From page 151... ...
· If the FFPR has not been achieved, then the desired FFPR can be multiplied by the estimated number of eligible persons in the eligibility category.15 This strategy can be represented by the following equation, assuming that there is a four-year time difference between the year for which the budget is prepared (year t) and the most recent year for which the number of eligible individuals can be estimated (year t - 41: 15A variant of this method is to use a weighted average of coverage rates for the past three years, presuming that this would be a more stable estimate of the coverage rate experienced over the time period.
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From page 152... ...
is equal to: Current USDA Method: FFPt = 0.80 x E' = 0.80 x E' 4 recalling that the USDA assumes that eligibility does not change over the four-year prediction period. Table 9-3 examines the percentage difference between the predicted number of participants (made using the USDA's current methodology to estimate eligibility and participation)
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From page 153... ...
In 1996 and 1997, USDA's predicted number of participants exceeded actual numbers of participants. However, since 1997, the USDA methodology has led to a growth in the underestimate of the actual number of participants.
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From page 154... ...
. In other words, with the panel's alternative strategy, CROP would be replaced by a coverage rate that is a weighted average of coverage rates of the previous three years (coverage rates from years t- 4, t- 5 and t- 61.
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From page 155... ...
However, when growth in the participation of these groups declines, the strategy of using past participation to predict future participation significantly improves the accuracy of the estimates. 16We could not provide estimates of the variation using a weighted average of past coverage rates since we did not have sufficient past years' data available to construct the weighted averages for all the years from 1996 to 2001.
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From page 156... ...
The Panel's Recommended Strategy for Estimating Participation After examining this alternative strategy for predicting participation and two of its three variants, the panel recommends that USDA forecast future numbers of participants in the following manner: Explicitly state the rate of participation in the WIC program that is consistent with the policy goal of fully funding the program. This is the full-funding participation rate (FFPR)
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From page 157... ...
If the group's coverage rate does not exceed the FFPR, then estimate the number of participants by multiplying the FFPR by the number of eligible individuals from the most recently available data. Alternatively, USDA could construct a three-year weighted average of past coverage rates.18 If the weighted average of coverage rates exceeds the FFPR, then the weighted average of past coverage rates for the group would be multiplied by the most recently available estimate of the number of eligible individuals from the participant group.
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From page 158... ...
Modeling such behavioral choices is more difficult. If the changes in eligibility rules reduce the size of the eligible population, then future participation rates may be higher than current coverage rates.
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