Map Projections

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Map Projections
Kansas Hospital Association 2002 STAT Book
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Thematic Mapping Tips

• Eliminate blank space. Focus is the map.
• Fill
• Continuous data Same color (or pattern) in
  progressive tones (or darkness)
• Categorical data Different colors (or patterns)
  but same tone (or darkness)
• Avoid hatching and solid black, if possible.
• Fill should promote intuitive understanding of
  the data.

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Fill
Kansas Hospital Association 2002 STAT Book
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Assumptions for Class Groupings

• Regions within the same class are the same
• Different class groupings represent significant
  and meaningful differences in regions.

Reportable Diseases in Kansas 2000 Summary
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Class Groupings

• How classes are grouped can significantly affect
  how the data is interpreted.
• How many classes?
• Four or five works well for Kansas counties
• Make sure reproduction method will allow user to
  distinguish between classes
• How to choose class breaks?
• Quantiles works well for percent or rate data.
• Natural breaks works well for count data with
  high variability.
• Facilitate appropriate comparisons.

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How classes are grouped can significantlyaffect
howthe data is interpreted.
How to Lie with Maps, 1991
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Same Data or Different Data?2000 African
American Population