How can you determine if a Theme contains hidden (aggregated) information?
In fact the process is relatively simple. Follow the steps described below.
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In the Project that you just created, click on the Cty06089.shp Theme.
A check mark will appear indicating that this Theme has been selected.
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Click the Open Theme Table button or select Table from the Theme menu.
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Notice that there is only one record in the Attribute Table for this Theme.
This means that there is no aggregated data in this theme. Close this Theme
Table.
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Select the Pla06089.shp Theme.
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Click the Open Theme Table button or select Table from the Theme menu.
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If necessary move and/or resize the Attribute Table so that you can see
both the View and the Theme Table.
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Notice that there are three records in the Theme Table. Each record represents
a city in Shasta County. From the Attribute Table, you can learn that those
cities are called Shasta Lake, Redding, and Anderson. However, while
there is data for three cities, there only appears to be one polygon in
the View. Successively select each record. Notice that a different portion
of the polygon is highlighted when each record is selected. This theme
contains more information than is being displayed in the View. This is
an example of aggregated data. In this tutorial, you will learn how to
disaggregate the data in this Theme.
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With the second record in the Attribute Table selected, compare your View
to Map 2.
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