Small Area Income and Poverty Estimates

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2000 Overview of School District Estimates

Data Revised 4/13/2004

The following text provides a brief overview of the estimates of related school-age children in families in poverty for school districts for income year 2000.


The No Child Left Behind Act of 2001 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. We base these estimates on Census 2000 and the income year 2000 SAIPE model-based estimates of poverty for all counties. We provide estimates for school districts according to their 2001-2002 boundaries.

Estimates released

Three estimates are provided for each school district: total population, the number of school-age children (ages 5-17), and the number of related school-age children in families in poverty. Where two districts divide the children of an area between them by grade, the estimates do so as well. The number of related school-age children in families in poverty in each school district is provided as a component of the determination of basic Title I grants. The estimate of the total population of each district is provided for use in the small district (less 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 allocating concentration grants. A true poverty "rate" for children cannot be determined from these figures, because the numerator and denominator refer to slightly different universes.

The school district estimates for 2000 are based upon tabulations of poverty in income year 2000 from reports in Census 2000, using school district boundaries corresponding to school year 2001-2002. These tabulated data are then combined with the SAIPE county estimates of poverty for income year 2000, utilizing methods consistent with those employed in the series of school district estimates provided since income year 1995. Thus, by construction, the SAIPE school district estimates are arithmetically consistent with the SAIPE county and state estimates and with the national estimate from the Current Population Survey (CPS) Annual Social and Economic Supplement (ASEC)- the official source of national poverty estimates.

Spatial Boundaries of School Districts: We provide poverty estimates for income year 2000 for all school districts in the Census Bureau's TIGER database, updated by the School District Boundary Survey, which the Census Bureau conducted for the Department of Education in 2001. You can find maps of 1999/2000 school districts at the Census Bureau's American Fact Finder (see these instructions on how to get to school district maps in the American Fact Finder) or the National Center for Education Statistics (NCES) School District Demographics website. We also tabulate the data for all occupied areas which the TIGER database shows not assigned to any school district, known as "balances" of the counties in which they occur, whether they comprise a single compact area or not.

Grade Ranges of School Districts: For each school district, our estimates pertain to all resident school-age children ages five to seventeen, inclusive, whether enrolled in public or private school, or not enrolled. In most areas, districts called "elementary" or "unified" are, no matter their names, responsible for providing education in 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.

In some areas of 17 states - Arizona, California, Connecticut, Illinois, Maine, Massachusetts, Montana, Nebraska, New Hampshire, New Jersey, New York, Oregon, Rhode Island, South Carolina, Tennessee, Vermont, and Wisconsin - there are separate "elementary" and "secondary" school districts, each exclusively responsible for providing education in some grades in their shared territory. In these areas, data for school-age children are allocated between districts in which they reside on the basis of the grade range of the district and the grade assigned to the child. Four states - Massachusetts, Oregon, South Carolina, and Tennessee - have described a few school districts with different grade ranges in different parts of their territory. 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 derived from past surveys, from the most recent published data in the NCES Common Core of Data , from direct calls to districts, and from an effort to assign a single grade range to each district which, 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: 1) where 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, 2) where an "elementary" and "secondary" district are present, data for children whose assigned grade is claimed by both are allocated to the "secondary" district, and 3) where 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: In order to tabulate the data for each child in a single district, where districts overlap, each child is assigned a grade. In data from the Census 2000 sample, where answers 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, K, 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 2001-2002 school district, to which that child is said to be "relevant," we tabulate for each district:

  • the number of "relevant" children ages 5-17, inclusive;
  • the number of such 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 age 5-17 related by blood, marriage, or adoption to the householder of the housing unit in which they reside. The householder and the spouse of the householder, foster children, other unrelated individuals, and residents of group quarters are not "related children".

Constructing SAIPE estimates

The SAIPE procedure for estimating poverty among 5-17 year-old relevant children 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 overlaps two counties, for example, we make estimates for the two parts separately and then combine them. If a school district is wholly contained in a single county, it is composed of a single piece.

The first step in making the school district poverty estimates is to estimate poverty rates for income year 1999 from Census 2000. The poverty rates for relevant school-aged children in families are estimated using a method called "estimated best linear unbiased predictor" (EBLUP) with a simple model. Using EBLUP, the estimate for each school district piece in a county is the weighted average of the direct sample estimate (produced as described above) for all of the school district pieces in that county. The weight for a school district piece depends on the relative variance of its sampling error and the variance between the school district pieces' true poverty rates within the county. The effect of this procedure is to "shrink" the estimates toward a county-wide poverty rate, so we often refer to this kind of estimator as a "shrinkage" estimator.

School district pieces can be very small, in which case the sampling-error variances of the estimates from Census 2000 sample data can be very high. In extreme cases, the Census 2000 estimates of the number of people in poverty in a school district might be zero or may exceed the population. Since these estimates are used throughout the decade, the effects of large sampling errors can have lasting effects. The shrinkage procedure produces estimates of poverty rates that are greater than zero and less than one in nearly every case. Further, the overall magnitude of the error is reduced under the fairly general model for which these estimates are derived.

To get estimates of the numbers of 5-17 year-old relevant children in poverty in families, we multiply the shrinkage estimate of poverty rates by the Census 2000 counts of the numbers of relevant related children 5-17 years of age. The numbers of people in poverty are then adjusted, using "controlled rounding," to get a result with the following properties:

  • The number of people in poverty in the pieces in a county adds up to the SAIPE estimate of the number of people in poverty in their counties for income year 2000.
  • The number of people in poverty in the school district pieces are integers.
This is possible, in part, because the county-level estimates have already been adjusted so they have the same properties relative to the states, which, in turn, have the same properties relative to the national CPS ASEC estimated number of school-aged children in poverty.

The controlled rounding has the approximate effect of calculating the shares of a county's people in poverty who reside in the school district pieces from the shrinkage estimates and apportioning the SAIPE county estimated people in poverty to the school district pieces according to those shares. The final step is to reassemble the school district pieces into the school districts, simply by adding their controlled-rounded numbers of people in poverty together.

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