Abstract
This document explains how to use the Allocate (Census 2000 extraction software) to create a GIS dataset that combines boundary data with Census data.
Choosing a Boundary File
You must provide the spatial files that define your area. Select and move the boundary file you wish to use as your selection criterion using the instructions for accessing spatial data on the EDS lab computers. If you need assistance, ask a consultant.
Start the Census extraction software by selecting "Portfolio Allocate" from the program applications (in Start Menu under EDS -> Census -> Portfolio Allocate).
Choose the Summary File
- Under "Current Database Set" use the pulldown menu to choose your Summary File.
- Only if you want to save your work so you can return to it at another time, do you need to specify a path and file name in the "Current Workspace File" window.
Read in your Spatial Data
- Click on the 'Pick Geography' tab.
- Then click on the arrow to open the 'File' menu to add your spatial
data file to your Summary File data extraction and start the selection
by highlighting "Add Polygon File."
Note: It is not necessary to select another geography in addition to the shapefile, doing so may cause problems.
- When the 'Open' dialog box opens, navigate to your EDS workspace and
select your spatial data file. If you do not see your file, you may
need to change your 'Files of Type' selection located near the bottom
of the dialog box to the appropriate file type.
- You will then see a dialog box asking you to select the field in the
spatial data file that will match to Summary File data. Usually you can
except the default. Choose the field that uniquely describes the level of
geography at which you want to map. If you are unsure, accept the
default or check the documentation for the shape file, or open shape
file and see what the variables contain.
Defining the File
- Click on the 'Output' tab.
- Choose a name for your output file and
your desired file format by selecting the 'Save As' button.
- In addition to specifying the name and folder for your file,
you must choose the file type appropriate for the GIS software you
intend to use: a MapInfo format (
.tab), a MapInfo Exchange Format (.mif/.mid), an ESRI format (.shp) or an SRC Geography file (.geo).
Selecting the Census Variables
- For a detailed explanation about selecting variables see the guide, Allocate for Basic Data Extracts.
- Note that Allocate will automatically generate a field called KEY that combines all the geographic codes that uniquely identify the polygons at your chosen level of geography . It will also create a field called NAME that contains a text description of the lowest geographic code within that KEY.
- If you want the code for any other level to use as a label on your map, select the variable with that code from the Geographic Identifiers folder.
Retrieving the Output
- With all the above steps completed, clicking on the FINISH button will prompt the program to write out the files that comprise the GIS dataset plus a text file that describes the components of the file.
- The "Processing Finished..." window (shown below) will appear asking if you want to open the files. Do not open the files.
- Close this window, exit Allocate, and open the files with the GIS
application software you choose.
- For help with the next step, refer to the "Importing the Map"
section in one of these EDS guides,
Mapping Geolytics' Census Data Using ArcMap
Nicole E. Fox
Academic Information Systems
