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1. What is SAIPE?

SAIPE is the Small Area Income and Poverty Estimates program of the U.S. Census Bureau. We produce model-based estimates annually of income and poverty for school districts, counties, and states. We do not produce projections or estimates for other geographic units such as towns, cities, or metro areas. The following estimates are produced:

School districts:

  • Total population
  • Children ages 5 - 17
  • Related children ages 5 - 17 in families in poverty

Counties and states:

  • Children under age 5 in poverty (states only)
  • Related children ages 5 - 17 in families in poverty
  • Children under age 18 in poverty
  • All people in poverty
  • Median household income

For more information, please see our About SAIPE page.

2. Why are SAIPE program poverty estimates recommended for use in Title I allocations?

SAIPE estimates are specifically designed for use in annual Title I allocations to school districts. The SAIPE methodology combines the 1-year American Community Survey (ACS) estimates with other data sources to provide more timely, precise, and stable estimates than the 5-year ACS estimates alone. [Most school districts, about 93 percent, have total population less than 65,000 and so do not have 1-year ACS estimates.]

There are several attributes of SAIPE that are relevant for its use in the Title I program. First, SAIPE provides the most current school-age poverty estimates available for all school districts and counties in the U.S. regardless of population size. SAIPE annually is released just a few months after the 1-year ACS estimates and is released two years prior to the most comparable year of ACS 5-year estimates. Second, SAIPE estimates are more sensitive to annual variation in economic conditions than 5-year ACS estimates since the SAIPE estimates use single-year source data. Nonetheless, the SAIPE estimates are fully consistent with the 5-year ACS estimates over time, if averaged over five years in a similar way. Third, SAIPE estimates incorporate school district boundary updates from the latest available School District Review Program, whereas the ACS estimates often incorporate these school district boundary updates a year later. Fourth, SAIPE estimates incorporate "grade relevance," whereas ACS estimates do not, which matters for elementary and secondary school districts which are not unified school districts.

Finally, for areas with small population size, SAIPE provides more precise estimates than the 5-year ACS estimates; that is, SAIPE estimates contain less uncertainty and have lower error variance. This attribute is important because better precision allows the SAIPE estimates to avoid the discrete estimates of zero (or near-zero) poverty that occur frequently in survey-based estimates, even in 5-year ACS estimates. Furthermore, the better precision means that the SAIPE estimates for smaller districts display more stability over time, i.e., less year-to-year volatility, leading to more stability in the allocations based on the poverty estimates. Note 5-year ACS estimates are not recommended for making year-to-year comparisons due to overlapping years in the adjacent 5-year periods.

3. How are the SAIPE program's state and county estimates constructed?

We use statistical models to create the estimates. The models relate state and county estimates of income and poverty from the American Community Survey (ACS) to other indicators of income and poverty. These indicators are based on summary data from federal income tax returns, SNAP benefits data (formerly known as Food Stamp Program data), decennial census data, postcensal population estimates, Supplemental Security Income recipiency, and economic data from the Bureau of Economic Analysis (BEA). These estimates are then combined with direct estimates from the ACS sample to provide figures which are more precise than either set alone. This is a standard method for making statistical estimates for small areas. We refer to the final combined estimates as "model-based." More information is available at Methodology.

4. How are the SAIPE program's school district estimates constructed?

The SAIPE county-level estimates of poverty are allocated to the school districts within the county using estimated within-county shares (see Question 3 for information on how county and state estimates are constructed). These within-county shares are estimated by combining shares from two sources: estimated shares from the sample data collected with the prior decennial Census (for 1989 SAIPE through 2009 SAIPE), the 5-year ACS (for 2010 SAIPE onward), and tax poverty shares calculated from aggregate federal individual income tax returns. You can find more information on SAIPE methodology in the Methodology section. For more information on data inputs see Model Input Data.

5. What happens when there is a change in county definition?

Any time a name or substantial boundary change occurs, SAIPE accounts for this by using up-to-date names, boundaries, and Federal Information Processing Standards (FIPS) codes for all data released about the year for which the change is effective. For more information on historical county changes, please see below.

6. Does my school district poverty estimate reflect the current school district boundaries?

Each new SAIPE data release reflects the latest inventory from the School District Review Program, which collects updated school district boundaries and grade ranges every year. For more information, please visit the following page:

7. What is the definition of poverty?

Poverty status is defined by family; either everyone in the family is in poverty or no one in the family is in poverty. The characteristics of the family used to determine the poverty threshold are: number of people, number of related children under 18, and whether or not the primary householder is over age 65. Family income is then compared to the poverty threshold; if that family's income is below that threshold, the family is in poverty. For more information, please see Poverty Definition and/or Poverty.

8. Why does the SAIPE estimate not match the Free and Reduced-Priced Lunch (FRPL) count for my school district?

Free and Reduced-Priced Lunch (FRPL) numbers use a different income threshold than the SAIPE estimate, and are therefore not comparable. The SAIPE program poverty estimates are based on the official measure of poverty as defined by the federal government. FRPL program counts, although informative about the economic status of a school district, will not match the official federal poverty measure. First, FRPL has different income levels for eligibility: 130% for free and 185% for reduced-priced lunches. In addition, FRPL eligibility is based on the income guidelines published by the U.S. Department of Health and Human Services. For the 2021 SAIPE estimates, the official Census Bureau poverty threshold for a family of four containing two related children under age 18 was $27,479 compared with $27,750 set by the 2022 poverty guidelines.

Children in a similar family would be eligible for the free-lunch program as long as family income did not exceed $36,075, and eligible for the reduced-price lunch program if family income was below $51,338. (These guidelines refer to eligibility criteria for school year 2022-2023.) Note the 2022 HHS poverty guidelines are approximately equal to the Census Bureau poverty thresholds for calendar year 2021, as discussed at HHS Poverty Guidelines.

9. Does the SAIPE program incorporate data from the American Community Survey (ACS)?

Yes. In its final report, the National Academy of Sciences' Panel on Estimates of Poverty for Small Geographic Areas (2000) recommended that the Census Bureau investigate using estimates from the ACS in models for small area income and poverty estimates. Full implementation of the ACS began in January 2005, and the SAIPE program incorporated those data into the 2005 estimates and forward. The county and state estimates utilize the 1-year ACS data, and the school district estimates also utilize the 5-year ACS data. All prior years of estimates were created using data from the Annual Social and Economic Supplement (ASEC) of the Current Population Survey (CPS). See Estimation Procedure Changes for the 2005 Estimates for more details. 

10. How does SAIPE compare to other estimates of poverty and income produced by the U.S. Census Bureau?

The U.S. Census Bureau reports income and poverty estimates from several major national household surveys and programs: the Annual Social and Economic Supplement to the Current Population Survey (CPS ASEC), the American Community Survey (ACS), the Survey of Income and Program Participation, Census 2000 Long Form, and the Small Area Income and Poverty Estimates Program (SAIPE). Each of these surveys differs from the others in some ways, such as the length and detail of its questionnaire, the number of households included (sample size), and the methodology used to collect and process the data. The SAIPE program uses data from a variety of sources, to create statistical models to produce income and poverty estimates. It is important to understand that different surveys and methods, which are designed to meet different needs, may produce different results. For more information about the various surveys, please visit the following page:

11. Why does the population estimate for children age 5-17 not match my school district's enrollment number?

The SAIPE estimate is not an enrollment number; rather it is an estimate of school age population for children living within school district boundaries. This estimate excludes children who live outside the district but attend schools within your district boundaries since all children are counted in the district in which they reside. Further, the SAIPE estimate does not account for children living outside the family unit such as foster children and those in institutional facilities. The U.S. Department of Education accounts for these children in their allocation formula.

12. Why is my school district's poverty estimate different than the neighboring school districts?

We expect to see differences between poverty rates for school districts within a county, even among those with similar demographic and economic profiles. Differences in sub-county poverty ratios are one reason why Congress directed the U.S. Department of Education to make fund allocations directly to school districts. Differences that exist among the SAIPE program's school district poverty estimates within a county are based on federal tax return information as well as income information from the 5-Year American Community Survey (ACS).

13. Why are the SAIPE program estimates not reflective of the current year?

With its release of 2006 and 2007 SAIPE estimates in December 2008, the SAIPE program reduced the release lag in SAIPE program estimates by an additional year. The estimates are as current as feasible given the timescale of availability of the various survey and administrative data used. For example, the SAIPE program's 2007 estimates utilized federal tax return data for 2006, which were filed in 2007, and were available to our program in 2008. The 2007 SAIPE estimates also used data from the 2007 ACS which were collected throughout 2007, tabulated and made available to the SAIPE program in August 2008.

15. Why are there no county-level SAIPE program estimates for income year 1996?

Prior to release of income year 1998 data, county data were produced every two years, for odd-numbered years. The Improving America's Schools Act of 1994 required estimates of poverty for school districts every two years. Both state and county-level estimates are produced as the building blocks for these estimates. We began producing county estimates for even-numbered years in 1998 to meet the demand for more current county-level estimates. State-level estimates have been produced annually since 1995 to meet requirements of The Personal Responsibility and Work Opportunity Reconciliation Act of 1996. School district estimates are also produced annually as required by the No Child Left Behind Act of 2001.

16. Is the 2010 Census used in the population estimates used for SAIPE?

Starting with the 2010 SAIPE estimates, the population estimates used in the production of SAIPE utilize values from the 2010 Census. More information about the July 1, 2010 population estimates is available on pages 4-5 of Methodology for the Intercensal Population Estimates: 2000 to 2010.

14. What are confidence intervals? What do they mean?

A confidence interval is a range of values that, with some level of certainty, contains the true value the estimate is approximating. For example, each state and county estimate is listed with a 90-percent confidence interval. This means that for a particular estimate, if we carried out our estimation procedure and created a confidence interval 100 times, the actual value that the estimate is approximating is in that interval approximately 90 out of the 100 times. For more details about confidence intervals, please check a basic explanation of confidence intervals. For information on confidence intervals of the difference between two estimates, please check the general cautions page.

17. How can the SAIPE program's estimates be improved?

We see two ways to improve the statistical precision of the income and poverty estimates. First, by improving the models, and second, by improving the input data. We continue to explore and assess the utility of alternate model formulations and statistical approaches. The current estimation methods use administrative record sources uniformly available for the entire nation. If access to administrative record data at both the federal and state levels were expanded, we could explore new variables and potentially improve the accuracy of the model-based estimates. We welcome suggestions, see Contact Us.

18. What should I do if I believe a SAIPE program estimate is wrong?

Please see Challenges for information about challenges to the SAIPE program estimates.

19. Where can I find the estimates of population used as denominators in the SAIPE poverty rates?

Estimates of county and state poverty universe data used as denominators for SAIPE poverty rates are available in the SAIPE Interactive Data Tool or from the SAIPE Model Inputs Data Tables.

20. If I have further questions, whom should I contact?

For assistance, please contact the Census Call Center at 1-800-923-8282 (toll free) or visit ask.census.gov for further information.


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