SNAP, previously known as Food Stamps,is reported on a household, rather than individual, level in the CPS. Therefore, each member of the household will report the same benefit amounts and time receiving benefits. For example, if one person in the household reports receiving $1,000 in benefits for four months, everyone in the household will report the same.
Target data for the imputation came from official SNAP data. In Fiscal Year 2014, an average of 22.74 million households claimed about $70 billion in benefits.
Recipients and benefits are imputed using a two step procedure. First, participation is imputed to match administrative totals. Second, we impute an adjustment ratio for benefits in order to match total benefit amounts.
We initially calculate net income according to program rules:
- Gross income for each household is attained by summing up the earned and unearned income of all household members.
- A deduction of 20% of earned income is applied.
- An additional deduction is applied according to household size
| Size | Deduction |
|---|---|
| <= 3 | $155 |
| 4 | $168 |
| 5 | $197 |
| >= 6 | $ 226 |
| Source |
- For households with members ages 60 or older, medical expenses exceeding $35, if they are not paid by insurance or someone else, are also deducted
- Child support can be deducted
- Dependent care and shelter costs may also be deducted. We use the average official numbers of $10 and $290 a month. These costs are not provided by the CPS, so we instead use numbers from the USDA.
We then use the following regression to determine the likelihood of a household participating in the program:
indicator = α + β net income + β household size + β disability + β number of children + β ABAWD + β welfare participation + ε
Able-Bodied Adults Without Dependents (ABAWD) are not allowed to stay on SNAP for more than three months, thus their households have a lower chance of receiving benefits.
Disability and welfare participation are included to indicate any disabilities in the household and participation in other welfare programs, respectively.
SNAP rules set upper bounds on monthly income in order to be allowed to participate in the program, the highest of which is $5,490. Therefore, we only run households with monthly income bellow this level through the model.
Households are then ranked by the probability of participation, and, for each state's subgroup, their weights are summed until they reach the administrative level. According to CPS and USDA, the gap between individual and household recipients reported to the CPS and administrative totals is 10.5 million and 10.3 million, respectively. Because of this, the size of each household is limited to one person when ranking participation probability. This is the only way both individual and household numbers can match administrative totals.
For each imputed household recipient, we assign the average benefit amount for their state. We then calculate the total dollar benefits for each state and compare imputed benefits to SNAP administrative data. The accuracy of our imputations varies state-by-state, so adjustment ratios are determined for each state by dividing total administrative benefits by total imputed benefits. Most ratios are close to one and are used to either increase or shrink each household's benefits.
The following variables will need to be updated in the model and this document when moving to the next year:
- Deduction amounts based on household size
- Average dependent care and shelter costs
- SNAP income eligibility standards
- Total benefit and participation levels
- State-level targets