Graphics Best Practices
Anna Jursik, Lester Shen, and Jenny Edwards, March 13, 2013
Lunch and Learn
Lunch and Learn: Graphics Best Practices
General Principles
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Consider the audience
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Establish hierarchy
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Stick with established patterns
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Minimize “chartjunk”
Minimize “chartjunk”
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What is the “smallest effective difference”?
Find the smallest effective difference
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Account for a multivariate world
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Post hoc ergo propter hoc
Courtesy of Michael Blasnik
Lunch and Learn: Graphics Best Practices
Displaying Numbers
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Averages
+ Mean
+ Median
+ Mode
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Averages
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Averages
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Averages
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Significance
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Significance
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Consistent Scales
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Consistent Scales
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Consistent Scales
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Reading in City Schools – 2nd Grade
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Full axis
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Error bars
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Error bars
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Show Me the Data
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Show Me the Data
Chart Types, Color, and Formatting
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+ Line Chart: Show Trends
What type of chart to use?
What Type of Chart to Use?
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+ Column or Bar: Discrete Repeating Units
What type of chart to use?
What Type of Chart to Use?
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+ Pie Chart: Emphasize A single value, or extremes (Large or Small Values)
What type of chart to use?
What Type of Chart to Use?
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Better choice: Radial Treemap
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Legends are overused
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Condos
Single Family
Peak at 172 Days
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Use legends if space is tight
Make sure legend order reads in the same order as data, and use color to assist
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General Color and Format Rules:Don’t overuse: maintain smallest effective differenceUse color and formatting to group similar types, to
show scale or trendsReserve different formatting dimensions to highlight
what you care about
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US Injuries + Fatalities per Billion Passenger-Miles(2002-2004)
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Portland’s Transportation Carbon Footprint
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Color-Blind Considerations
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Use tick marks when you want to show discrete measurements
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Create a logical order
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