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Small Area Income and Poverty Estimates

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Small Area Income and Poverty Estimates (SAIPE)

School District State Map Series

Overview

This page-size map series is organized by state and uses data from the Small Area Income and Poverty Estimates. The maps display percent of school-age children in poverty at the school district level. Additional characteristics displayed for the state-level are poverty by metropolitan and micropolitan areas and median household income.

School District Geography

The school district maps display a composition of unified and elementary districts only. Secondary school districts were omitted because often they have the same boundaries as elementary districts. Cartographic generalization was applied to simplify and smooth line work, therefore, shapes may not represent exact boundaries and extent of districts. For an official map of school district boundaries, refer to the TIGER database listed in the Data Sources section below.

Data Sources

School District boundaries: U.S. Census Bureau's TIGER database
http://www.census.gov/geo/www/tiger/index.html

Poverty Estimates: U.S. Census Bureau, Small Area Income and Poverty Estimates (SAIPE) Program
http://www.census.gov/did/www/saipe/index.html

Data Classification

The natural breaks classification method was used to determine class breaks. The natural breaks method maximizes between class differences but minimizes within-class differences to ensure dissimilar values are separated into different categories. Natural breaks were determined at the national level so any individual state may not have all the categories present. The class breaks were then adjusted to align with national values to aid with visual comparisons.

Map projection

State-based Albers Equal Area



Interactive Map Application

Overview

The SAIPE interactive map application is a Flash-based tool for data visualization purposes. The map application is intended to deliver more dynamic and interactive content and provide a better end-user experience. To view this application your system must have the Adobe Flash Player version 10.x or higher installed. This application is best viewed using 1024 x 768 pixels screen resolution or higher.

Please download the latest free Adobe Flash player if it is not installed.

Mapping Capabilities

The core functionality with this application is to provide the end-user with an interactive map to display the various estimates as thematic maps. Estimate maps for each geographic level (state, county, and school district) are already classified and colored for optimal viewing. The interactive components are comprised of mouse over tool tip windows to display contextual information, dynamically linked tabular data, navigation tools to zoom in and zoom out, and multiple background images such as satellite imagery, street maps, and elevation to overlay census data and geography.

Boundary Limitations

Cartographic generalization was applied to simplify and smooth line work; therefore, shapes may not represent exact boundaries and districts. As a result of cartographic processing, school districts that contain multiple shapes may have duplicate rows in the table display. For official boundaries for school districts please view the reference maps produced by American FactFinder. The links to the maps can be found in the school district interactive table reference map results field.

Data Sources

Census boundaries: U.S. Census Bureau's TIGER database
http://www.census.gov/geo/www/tiger/index.html

Poverty Estimates: U.S. Census Bureau, Small Area Income and Poverty Estimates (SAIPE) Program
http://www.census.gov/did/www/saipe/index.html

Software

The application was developed using the Adobe Flex 4.0 framework, ArcGIS API for Flex 2.2 and ESRI ArcGIS server 10 on Red Hat Linux.

General User Notes

The accessible data files used in this mapping tool are available at http://www.census.gov/did/www/saipe/data/index.html.

The school district percentages shown are not true poverty rates, as the denominator includes all children ages 5 to 17; whereas true rates are limited to non-institutional children in families.

The Unified and Secondary map layer includes only those districts that are operationally unified or secondary. There are areas for which the state has identified an operationally elementary district, but no secondary. For these areas, the Unified and Secondary map layer will not be displayed thematically.


Childhood Poverty, 1999 2012

Methods

The Small Area Income and Poverty Estimates (SAIPE) derived poverty surface was produced using spline interpolation. A spline interpolation uses a set of values located at specific points, and creates a continuous surface over a given area. In this case, child poverty rates are interpolated from the geometric center of elementary and unified school districts. These rates are defined as the ratio of related children in poverty ages 5 to 17 divided by the total number of children ages 5 to 17.

The applied spline interpolation method constrains interpolation to values inside respective states. In this way, state surface comparisons can be made.

Symbology

The map symbology uses a standard deviation stretched color ramp designed to maximize the surface color range allowing for improved visual interpretation. The selected stretch essentially top codes the surface values at 50% of children in poverty. Values above this are symbolized at the highest value on the color ramp, or dark red in this case.

Map Projections:

  • Contiguous states: US Contiguous Lambert Conformal Conic
  • Alaska: North America Datum (NAD) 1927 Alaska Albers
  • Hawaii: North America Datum (NAD) 1983 State Plane Hawaii FIPS 1

Interpretation

Interpolated surfaces create bias where values are calculated across large distances, and should be interpreted with caution; however, the surface illustrates a discernible spatial pattern to poverty related to local phenomenon. 

Data Sources

Geographic boundaries: U.S. Census Bureau's TIGER database

Poverty Estimates: U.S. Census Bureau, Small Area Income and Poverty Estimates (SAIPE) Program

Source: U.S. Census Bureau | Small Area Income and Poverty Estimates |  Last Revised: December 11, 2013