SDViewer -- Analyzing National and Regional Patterns
SDViewer enables the analysis of national and regional patterns, showing how school districts relate to one-another and other types of geographic areas. In those states where elementary, secondary, and unified districts co-exist, it is easy to see geographic relationships -- how districts sometimes overlap. Since SDViewer includes all school districts it is possible to get answers to questions like:
Which school districts have more than 25,000 enrollment?
Which school districts have a percent school age children in poverty of more than 25%?
Which school districts are located in county X or metro Z?
Which school districts are located in urbanized areas?
Which school districts meet my demographic criteria?
The SDViewer start-up is controlled by three GIS project files (GPRs), one for the contiguous states (sdus.gpr), one for Alaska (sdak.gpr), and one for Hawaii (sdhi.gpr). The three GPR files establish the view that appears in the map windows. Project files are used to automatically open map files that enable viewing of certain types of geography, subject matter data, and viewing attributes of each.
Some familiarity with the content and role of the GPRs can help you better utilize the potential and features of SDViewer. The sdus.gpr standard structure opens these map files (polygons except as noted):
Unified school districts
Secondary school districts
Elementary school districts
All U.S. ZIP Codes (points)
Mexico and Canada (do not appear in legend, used as general reference only)
In addition to these map files (in shapefile structure), an additional layer is used to demonstrate how SDViewer can focus analysis on a particular set of districts that have common features of interest. The GPR file includes the code shown at the right. This code references the USSDU00.SHP (U.S. unified school districts shapefile). The QUERY record is used to manage the view of this layer to only include districts where the enrollment in the 2002-03 school year is more than 25,000 (large districts) and percent population ages 5 to 17 years in poverty greater than 25-percent. For example, this query may be of assistance in analyzing large districts with high poverty. The query provides an easy way to determine how many districts meet these criteria, how and where they are distributed geographically, and exactly which districts are included (a list). Equally important is the ease with which this specification can be changed; edit the parameters to the right of the query command to view different sets of districts. (see box at right) It may turn out in regional analyses that 30 percent is a better poverty cutoff, or enrollments of 27,000 a better size cutoff rather than 25,000. It is easy to change the statement and view different sets of districts.
The following view shows the results by viewing this layer. The layer described by the GPR code shown above is checked and made active to view these districts of interest. Unified districts meeting the criteria are shown in red. To view a list of these districts, the Tools>QueryList is used (see in view shown below). When Tools>QueryList is invoked a query box appears. This enables you to enter SQL-type specification for a query to be performed on the database. In this example, the query is the same as used to generate the map view.
The query provided above generates a display of the districts that meet the criteria. See the list of districts in the lower right listbox in the view presented below. As you click on a row/name, the full citation is displayed at the right end of the status bar.