Major Concerns of the Cartographer

1. Data Classification

2. Areal Symbolization

3. Legend Design

Choropleth map
a form of statistical mapping used to portray discrete data by enumeration units.
Enumeration units
typically used in choropleth maps – countries, states, provinces, counties, census tracts, or any other unit that has associated attriibute data that correspond to the enumeration units.
3D Histogram
A choropleth map may be though of as a 3d histogram or a stepped statistical surface. A choropleth map is simply a planimetric representation of this 3D prism model.
Attribute data
correspond observation for observation to the individual enumeration units.
Geographic Area
Area that is being related to the enumeration units.
Enumeration Attribute data
totals or derived values.
Total values
usually not acceptable
Derived Values(rates or ratios)

the different kinds of derived values




Density,Ratio, Proportions
Preliminary Considerations in Choropleth Mapping

1. Geographic Phenomena

2. Map Scale

3. Number and kinds of Enumeration Units

4. Data processing

5. Data Classification

6. Legend Design, Areal Symbolization, and Base Map Design


Legend Design

1. Increse left to right

2. Large numbers use commas

3. Title should be relevant to what is being mapped


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