How not to lie with maps: Design
choices for quantitative data
Catherine Riihimaki, Drew University
GIS at Drew
• No geoscience program (except me)
• One GIS course (so far) offered once per year
• GIS is one of 4 required courses for
Environmental Studies
• GIS now satisfies a few Gen. Ed. categories:
Natural Sciences, Interdisciplinary,
Quantitative
GIS at Drew
• No geoscience program (except me)
• One GIS course (so far) offered once per year
• GIS is one of 4 required courses for
Environmental Studies
• GIS now satisfies a few Gen. Ed. categories:
Natural Sciences, Interdisciplinary,
Quantitative
Map Design
Challenges
• Nuts-and-bolts of
making a map
• Good vs. bad
design choices
– Aesthetic choices
– Misleading choices
Map Design
Challenges
• Nuts-and-bolts of
making a map
• Good vs. bad
design choices
– Aesthetic choices
– Misleading choices
Assignment
• Create maps showing population, racial
composition, and age composition of New Jersey
counties (data provided)
• Describe one conclusion each about how
population, race/ethnicity, and age are
distributed across NJ
• Describe and justify your design choices
– Color/symbol choices
– Normalization choices
– One alternative map design that you rejected
Key conclusions:
1. All maps provide selective truth
2. Cut-points can be manipulated to change meaning of choropleth maps
3. Count data should be shown with varying symbol sizes or should be normalized
to show density (e.g., population density instead of population)
Ways students can go wrong…
Inappropriate use of pie charts
Confusion about normalization
Ways students can go wrong…
Inappropriate use of pie charts
Confusion about normalization
Outcomes
• Reinforcing concept that map design must be
done carefully and deliberately
– Synthesis of article through designing maps
• Practicing quantitative concepts
– Normalization
– Chart usage
– Unequal group sizes (and other data limitations)
• Learning about New Jersey characteristics
– Must have some map interpretation to make them
look at the maps carefully