Proportional Symbol Mapping

Creating dot density maps using ArcGIS program

Visualizing spatial patterns of inequality over time.
The entire index’s range in 1970 is 5.09 – 12.50. The most common income inequality ratio is in between 6.91 and 9.61 for all the states except for northwest area and some cities in central United States. In addition, the inequality in the east side is more intense than the west side of the United States.
The entire index’s range in 2010 is 4.74 – 17.77. The most common income inequality ratio is in between 7.65 and 9.61 through the entire states except for the northwest area. In addition, not only the inequality in the east side is more intense than the west side but also inequality indexes on some cities in the east side had been significantly increased comparing the sizes of two circles in those areas.
GeovizLab4_Sohng_A-2
Two symbol approach
Two symbol approach has more information than difference symbol approach. It keeps the information of inequality ratio for each year. In addition, we can see which city’s inequality ratio had significantly changed since we can see the size difference of circle for each city.
GeovizLab4_Sohng_B-2
Difference symbol approach
Difference symbol approach shows the tendency or trend of income inequality in each city in the United States. Thus, we can see inequality of which city had increased/decreased. In addition, this approach partially shows which city performs better economic system more effectively.
Discuss which works better, and why?
It depends on the purpose of the map. Map A works better if the purpose of the map was to show the inequalities in each city between the year of 1970 and 2010 and changes of the inequalities at the same time. Because this map keeps and shows information of both years. However, map B works better if the purpose of the map was only to focus on the tendency or trend of income inequality of each city in the United States. It shows the growth/decline of income inequality more effectively as it only shows the change of inequality. Even though the map A also can demonstrate the changes, focusing and showing only the targeted information works better when there is a single purpose of visualizing the data.


Leave a Reply

Your email address will not be published. Required fields are marked *