Aaron Henning & Carl Sherlock Project 5 Thematic Maps Aaron Henning & Carl Sherlock

Thematic Maps Basics Transfer geographic data into geographic information Highlight one attribute’s geographic distribution Single purpose or “theme” in mind Review: Reference maps portray many attributes and features

Reference vs. Thematic

Thematic Maps Use abstract, graphic symbols that represent the quantities and qualities that make locations meaningful The use of colors and symbols to project attribute data Attribute data examples: density, counts, rates, etc. Cynthia Brewer’s presentation

Remember…

Thematic Mapping Counts Showing a symbol for each individual or group of individuals Fails when many individuals or groups are present and/or when location is unknown

Thematic Mapping Porportional Symbol Maps Also called graduated symbol maps They represent classes of counts not individual counts Useful for counts that lack location

Thematic Mapping Chloropleth – “place” & “value” Involves coloring geographic areas to represent categories of rates or densities Most common type of thematic map

Thematic Mapping Rates and densities Pie Chart Rates and densities Simply one count divided by another count In densities, the divisor is the magnitude of a geographic area Can be in various formats Bar Graph

Starting the Project Go to factfinder.census.gov Left side menu, hover cursor over “DATA SETS” Click on “Decennial Census”

Making sure you are selecting “Census 2000 Summary File 1”, choose “Thematic Maps” on right hand menu Select “county” under geographic type Select your state, then select your county, and hit “Next” This will display all of the data themes that can be displayed on a map  pick one and click “Show Result”

Directly above map where it says “Display map by:”, select “Census Tract” from drop-down menu Adjust zoom and pan to make data as visible as possible

At top of left side menu under “Change…”, select “data classes” From here you can change classing method, color scheme, and number of classes

Classing Methods Review Quantile (percentile) Equal number of features in each class Equal Interval Equal range of values in each class Natural Breaks Divides features and/or range of values according to pre-existing groupings or divisions

When finished customizing, right click map and select “Save picture as When finished customizing, right click map and select “Save picture as...” (repeat for legend)

For this project, you need a total of 3 maps You have now successfully found and downloaded all data for your first map For this project, you need a total of 3 maps At least one needs to be of ACS Data From FactFinder homepage, hover over “Data Sets” and click on “American Community Survey” and follow same process

Take a moment to analyze your map – why is the data how it is? Why does the tract that corresponds to campus and downtown have the lowest percent of persons under 18? Think about this, it will help you with the write-up Map 1: Percent Persons Under 18 Years of Age

Finding Map Scale In bottom left corner of your map image, it will tell you distance across (Dg) The actual width of the image is ~6” (Dm) Remember the formula? S = Dm / Dg

Review Thematic Mapping Attribute data transformed into useful geographic information Designed with a central purpose or theme Different types of data are represented in different ways

References Baxter, Ryan. Census Mapping and Thematic Maps. GEOG 121 Lecture. 11/20/06 Brewer, Cynthia. Cartographic Inspirations for Designing Better Data Visualizations. GEOG 121 Guest Presentation. 10/11/06 Census Bureau FactFinder. Accessed 11/20/06. http://factfinder.census.gov ESRI Virtual Campus: Module 6. Accessed 11/19/06. http://training.esri.com The Pennsylvanian Marketing and Planning Center. Accessed 11/20/06. http://www.mapcenter.org/index.html

Help Aaron Henning – amh334@psu.edu Carl Sherlock – cfs5000@psu.edu http://www.personal.psu.edu/cfs5000/geog121_lab5.html Course Example http://www.geog.psu.edu/courses/geog121/projects/proj5_example.html