Bivariate maps show two themes on the same map. The graphic marks used to represent the themes may be different, as with proportional symbols on a choropleth map, or they may be the same. Bivariate choropleth and bivariate point symbol maps fall into the latter category. Although ArcGIS does not have any out of the box tools to make these same-symbol bivariate maps, in this presentation I introduce a new set of tools that can be used to ease the compilation of these maps. Combined with standard tools, it is now easier and faster to make these bivariate maps in ArcGIS.

1. 2013 NACIS Conference
October 10-11, 2013 | Greenville, SC
ArcGIS Bivariate Mapping Tools
Aileen Buckley, Esri

2. 2013 NACIS Conference
October 10-11, 2013 | Greenville, SC
Choropleth
ArcGIS Bivariate Mapping Tools
Aileen Buckley, Esri

3. The purpose of multivariate mapping
•
To display more than one variable simultaneously
• To allow for estimation of the degree or spatial
pattern of cross-correlation between variables
• Effectiveness of a method is related to readability
and accurate representation of the data

4. Cross-variable mapping
• Simultaneously
depict magnitude of variables
within homogeneous area for multiple map
themes
-
Bivariate mapping
Trivariate mapping

5. Bivariate choropleth maps
•
Maps that simultaneously
show two variables using the
choropleth map method
-
-
Choropleth maps use polygon
fills to represent quantitative
values
Greek χώρο– + πλήθ[ος]
“choro” (area/region) +
“pleth” = quantity/increase

6. What are the considerations when you use
choropleth maps?
•
Choropleth maps give the impression of
-
•
Uniformity in data within the data collection units
Abrupt breaks that occur at the unit boundaries
Use quantitative values that are spatially
intensive (i.e., do not depend on the size of the
unit area)

7. Learn more!
•
ArcUser, Winter 2013

8. Early examples

9. Early examples

10. http://www.census.gov/population/www/cen2000/atlas/pdf/censr01-103.pdf

12. Making Beautiful Maps

13. Cross-variable mapping
•
Limitations
-
-
•
Advantages
Because the number of
- This technique is useful for
classes the human eye can
simultaneously displaying a
distinguish is limited, crossfew variables (two or three)
variable mapping is generally
restricted to combinations of
either two or three variables • Recommendations
- It is often useful to also
Appropriate symbol (color)
provide separate maps of
selection is important for map
each of the variables shown
readability
on the bi- or trivariate map

14. Two ways to do this in ArcMap
Exploration
• Bivariate
renderer
Use this to render the
data on-the-fly
- Use this to create a live
legend (linked to the
renderer)
-
Presentation
• Bivariate
script tool
Use this to calculate the
quantile classes in the
feature class
- Use the Match to
Symbols in a Style
renderer
- Use the
LegendMaker.mxd to
make the legend
-

15. Bivariate renderer
•
Download the .zip file and unzip it
•
Register the .dll
Directory and
name of the file

16. Styles – based on Brewer’s color research

17. Brewer’s Color Schemes
•
Diverging color schemes
Brewer, Cynthia. 2005. Designing Better Maps,
with permission form CaGIS and Esri Press

18. Used to find intermediate colors
http://meyerweb.com/eric/tools/color-blend/

20. ArcMap styles

21. ArcMap styles

23. Making Beautiful Maps