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Small Area Income and Poverty Estimates

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2006 - 2008 Overview of School District Estimates

For an overview of the changes in methodology for the 2007 and 2006 estimates relative to the methodology for the 2005 estimates, see Constructing the SAIPE Program Estimates and Estimation Procedure Changes.

Background
The No Child Left Behind Act of 2001 (NCLB) directs the Department of Education to distribute Title I basic and concentration grants directly to school districts on the basis of the most recent estimates of children in poverty available from the Census Bureau. These estimates are produced under the Census Bureau's Small Area Income and Poverty Estimates (SAIPE) program. They are based on Census 2000, aggregated tax data, and the SAIPE program's model-based estimates of poverty for all counties.

The 2007 and 2008 estimates correspond with 2007-2008 school district boundaries, while the 2006 estimates correspond with 2005-2006 school district boundaries.

SAIPE School District Estimates
Three estimates are provided for each school district:

  • total population
  • children ages 5-17
  • related children ages 5-17 in families in poverty

The number of related school-age children in families in poverty in each school district is provided as a component of the determination of Title I grants. The estimate of the total population of each district is provided for use in the small district (fewer than 20,000 population) provision. The figure for school-age children is provided so that the proportion of children in poverty can be determined. This proportion is required for determining eligibility for grants. A true poverty "rate" for children cannot be determined from these figures, because the numerator and denominator refer to slightly different universes.

The 2008 school district estimates are based upon tabulations of poverty from Census 2000 and tax year 2007 IRS income tax data, using school district boundaries corresponding to school year 2007-2008, and combined with the SAIPE program 2008 county estimates of poverty. The 2007 school district estimates are based upon tabulations of poverty from Census 2000 and tax year 2006 IRS income tax data, using school district boundaries corresponding to school year 2007-2008, and combined with the SAIPE program 2007 county estimates of poverty. The 2006 school district estimates are based upon tabulations of poverty from Census 2000 and tax year 2005 IRS income tax data, using school district boundaries corresponding to school year 2005-2006, and combined with the SAIPE program 2006 county estimates of poverty. By construction, the SAIPE program school district estimates are arithmetically consistent with the SAIPE program county and state estimates.

Spatial Boundaries of School Districts
We provide poverty estimates for all school districts that are in the Census Bureau's TIGER database, updated by each School District Review Program; the most recent was completed in 2008. We also tabulate and produce estimates for all occupied areas not assigned to any school district. We refer to these areas as "balances" of the counties in which they occur, whether they compose a single compact area or not. Although we do not publish estimates for "balance of county" areas on our website, they are provided to the U.S. Department of Education for implementing provisions of NCLB and are available upon request.

Grade Ranges of School Districts
For each school district, our estimates pertain to all resident school-age children ages 5-17, inclusive, whether enrolled in public or private school, or not enrolled. Where two districts divide the children of an area between them by grade, the estimates do so as well. In most areas, districts called "elementary" or "unified" are, no matter their names, responsible for providing education for all elementary and secondary grades - either by operating schools themselves or by purchasing instruction from neighboring school districts - for all residents of their territory. In these areas, data for all people ages 5-17, inclusive, are tabulated in the district in which they reside.

Some states have areas with separate "elementary" and "secondary" school districts, each exclusively responsible for providing education in some grades in their shared territory.1 In these areas, data for school-age children are allocated between districts on the basis of the grade range of the district and the grade assigned to the child. There are also some states that have school districts with different grade ranges in different parts of their territory.2 In most cases, these are districts that are "unified" in part of their domain and "secondary" in the rest. The final tabulations and estimates reflect the combination of data honoring these distinctions.

Grade ranges for each district are collected during the boundary update and supplemented with phone calls to districts. We attempt to assign a single grade range to each district that, in the case of spatially overlapping districts, leaves no grade unclaimed and no grade claimed by more than one district. Occasionally the pattern of grade ranges of overlapping districts does not permit each grade to be assigned to exactly one and only one district. In these few instances, three simple rules are applied.

  • If a "unified" district is present, data for children whose assigned grade is claimed by two districts or not claimed by either are allocated to the "unified" district.
  • If an "elementary" and "secondary" district are present, data for children whose assigned grade is claimed by both are allocated to the "secondary" district.
  • If an "elementary" and "secondary" district are present, data for children whose assigned grade is claimed by neither are allocated to the "elementary" district.

Grades for Children
To tabulate the data for each district, each child is assigned a grade. In the Census 2000 sample, where responses to the "long-form" questions are available, 97 percent of children are assigned a grade on the basis of their edited reports of the grade in which they were enrolled. Because this question used response categories that represent multiple grades (PK, KG, 1st - 4th, 5th - 8th, 9th-12th, higher), the child's age in October was used to assign single grades from among those implied by the answer. For those not enrolled, the modal grade for their age in October (age on October 1, 1999 less 5) was assigned, provided that the grade assigned was not reported as having been completed. For Census 2000 short-form data, where school enrollment and educational attainment are not available, children were assigned the modal grade for their age on October 1, 1999.

With the Census 2000 record for each child assigned to a single school district, to which that child is said to be "relevant," we tabulate for each district:

  • "relevant" children ages 5-17, inclusive,
  • "relevant" children who are related to the householder and reside in families whose 1999 income falls below the poverty threshold appropriate to that family, and
  • the total population of all ages residing in the spatial boundaries of the district. (Note that because of overlapping districts, the sum of the total populations of the districts will exceed the total population of the nation.)

Related children are people ages 5-17 related by birth, marriage, or adoption to the householder of the housing unit in which they reside; foster children, other unrelated individuals, and residents of group quarters are not "related children."

Constructing the SAIPE Program Estimates
The SAIPE program procedure for estimating poverty among relevant children ages 5-17 in families works with geographical units we call school district-county-pieces. These pieces are defined as the intersections of school districts and counties (i.e., all of a district if it does not cross county boundaries and each county part separately for districts that do). If a school district has territory in two counties, for example, we make estimates for the two parts separately and then combine them.

The first part in making school district poverty estimates is to compute the school district piece tax-based child poverty rate, using federal tax information obtained from the IRS. The tax-based poverty rate for a school district piece is estimated by the product of the county related children ages 5-17 poverty rate and the ratio of school district piece to county share of "child tax-poor exemptions" over the share of total "child tax exemptions". For the 2008 school district estimates, the number of child tax exemptions and their corresponding poverty status are taken from tax year 2007 IRS income tax data. For the 2007 school district estimates, the number of child tax exemptions and their corresponding poverty status are taken from tax year 2006 IRS income tax data. For the 2006 school district estimates, the number of child tax exemptions and their corresponding poverty status are taken from tax year 2005 IRS income tax data. "Poor Child Exemptions" are defined as the number of child tax exemptions on returns whose adjusted gross income falls below the official poverty threshold for a family of the size implied by the number of exemptions on the form tabulated for each school district piece.

Not all tax returns can be geocoded down to a specific school district piece. However, the total number of exemptions in a county is known. These exemptions will be called the non-geocoded exemptions. The tabulated child tax exemptions and child tax-poor exemption counts are adjusted to reflect the appropriate grade range of the school district piece because age of child is not included on the income tax form. The next step in calculating the tax-based shares is to estimate the school district piece to county share of relevant children age 5-17 and relevant children age 5-17 in poverty from Census 2000. These shares are based on the methodology used prior to 2005 for school district poverty estimation (see Overview of School District Estimates 2004). The non-geocoded exemptions are also adjusted to reflect the target 5-17 year old population, then allocated to the school district pieces to minimize the difference between the tax-based shares and the corresponding census-based shares using the Minimum Change algorithm (for details see report: Small Area Estimation of School District Child Population and Poverty: Studying the Use of IRS Income Tax Data [PDF 373k]). After allocating the non-geocoded exemptions, the tax-based poverty rate for a school district piece can be computed.

The second part in creating the school district poverty estimates is to multiply the school district piece poverty rate to the official estimate of relevant child population for the school district piece. These estimates are then raked (ratio adjusted) to agree with the county estimates for number of children age 5-17 in poverty. Finally, the raked school district piece estimates are adjusted using "controlled rounding" to get results with the following properties.

  • The number of children in poverty in the pieces in a county adds up to the SAIPE program's model-based estimate of the number of children in poverty in their counties for the relevant income year.
  • The number of children in poverty in the school district pieces are integers.

The final step is to reassemble the school district pieces into the school districts, simply by adding their controlled-rounded numbers of children in poverty together.


1 States where districts may overlap: Arizona, California, Connecticut, Illinois, Kentucky, Maine, Massachusetts, Montana, New Hampshire, New Jersey, New York, Oregon, Rhode Island, South Carolina, Tennessee, Texas, Vermont, and Wisconsin.

2 States where grade ranges may differ within a district: California, Kentucky, Massachusetts, Oregon, South Carolina, Tennessee, and Texas.


Source: U.S. Census Bureau | Small Area Income and Poverty Estimates |  Last Revised: April 29, 2013