Part 3: ArcGIS software:
Activity: This will be a basic activity using cancer mortality data from
http://www3.cancer.gov/atlasplus/excel.html combined with county-level demographic data. We’ll
symbolize rates such that cancer and demographic data are represented simultaneously, and then
discuss ways in which the map display aids in determining spatial patterns. A third activity will then be to
discuss the limitations of county-level data, and to ask what other spatial data—particularly features like
waste and toxic release sites—we might try and gather and include in our map analysis. Finally we’ll
practice expressing the results of map analyses in ways that avoid committing the sin of the ecological
fallacy.
Task: Create a map of Texas counties showing population density, breast cancer rates in women (19701994) and per capita income.
Steps:
1) Go to StartAll Programs ArcGIS ArcMap 10
2) On the pop-up box, click “Cancel.” Then go to:
FileOpenComputerS:SoftwareLibraryGisDataKing_CancerJ_KingCancer_1
3) Save a copy of the map to your personal storage space (Y:, flash drive, etc.), so you can edit it
freely: FileSave AsYour_Name.mxd
4) Set the data paths so you can continue to use data from the server: FileMap Document
PropertiesPathnames (at bottom of page) Check “Store Relative Path Names”OK
5) Let’s set the map’s data frame to show the states and counties in a more proportional view,
such that distortions of area are minimized: ViewData Frame PropertiesCoordinate
SystemPre-DefinedProjected Coordinate SystemsContinentalNorth AmericaNorth
America Albers Equal Area Conic’Yes’ to warning
6) Since you’ll make changes to only the Texas layer, save a copy of cy_breast_TX.shp: Right-click
on cy_breast_TX.shpDataExport Data. In the ‘Output feature class’ field, change
‘Export_Output.shp’ to ‘cy_breast_TX.shp’ and change the ‘Output feature class’ path to your y:
drive or flash drive. Click OK. Say ‘Yes’ to add the new layer to the map.
7) Let’s quickly calculate & symbolize population density: Right-click on cy_breast_TX and select
‘Properties.’
8) Select the Symbology tab, and in the left pane choose ‘Quantities—Graduated colors.’
9) Look for the Fields box (above the Color Ramp) and for ‘Value,’ select ‘POP2000’ and for
‘Normalization’ select SQMI. Click OK.
10) Let’s make a second version of the map that symbolizes breast cancer rates for women (19741990): Click on the Add Data button
and browse to where you saved cy_breast_TX.shp. Add
a second copy of this file to map. Right-click on the file name:
PropertiesQuantities/Graduated colorsValue=”R_Fem_7094” and Normalization’none’.
Click OK.
11) Do you notice any patterns? Be prepared to describe what you notice.
12) Repeat the procedure of adding cy_breast_TX.shp to the table of contents, and try symbolizing
per capita income (Per_cap_in) and four occupation categories: Management/Professional
(Manag_prof), Administrative/Support (admin_supp), Service, and laborers—be sure to
normalize these against the total population.
13) Finally, symbolize per capita income as a graduated symbol instead of as a graduated color.
Adjust the background color to ‘none’ and set the symbol sizes to 2-14 (see below).
14) Drag and drop layers in the table of contents so that per capita income is layered on top of the
color scale map of breast cancer rates for women.
15) Click the save icon in the top tool bar.
16) To create an image from your map:
17) ViewLayout View; Insert(Title, North Arrow, Legend)
18) Adjust the elements so they create a legible map. Choose a title which includes the place name
(Texas), the geographic unit of aggregation, and mentions the data being symbolized on the
map, as well as the years of coverage (1974-1990 for the cancer data, 1990 for the income data).
19) Save the map as image: FileExport Map…Save as TypeJPEG and save to your personal
storage space.
Homework for GIS/Mapping segment
Using the map document you saved in class (your_name.mxd), create a one-page report that consists of
the following:



An image of your map, including a legend, a title, and a ‘North arrow’
A citation for the data source (provided on the LibGuide)
An original abstract (+/- 100 words) in which you describe and interpret the map, taking care to:
o Clearly differentiate between apparent correlations and inferred
causation.
o Provide statements that interpret the evidence provided in the map
you’ve made for a general audience.
o Avoid making an unsupported inference (AKA the ecological fallacy) by
choosing your language carefully and precisely. Use the terms provided
in the source’s metadata—units of measurement, terms for
geographical levels of aggregation (e.g. county)