Communicating GIS Lab 5

Proportional symbol mapping can be a useful tool when trying to display numerical data based on certain features. This week we experimented with the symbology and how to effectively communicate data to the user. Proportional symbology allowed us to use different sized symbols to represent specific numerical values for different areas. With the areas being proportional to each other based on the data it made it easy for users to draw conclusions based on the data. 

One particularly interesting feature we worked with was how to display positive and negative numerical data using the proportional symbol mapping. In the map below you can see that the same proportional symbols can be used creatively to display a positive value of the data (Green) and a negative value (Red). 

With the symbols staying the same size proportionally based on the absolute value of the numerical data we had to represent them as neutral in the legend and then explain the coloring system. This was a neat solution to an interesting problem. At first it seemed difficult to display the wide range of data in this map with something other than color ramps, but the proportional symbology made it quite simple in the end.

I think this type of symbology also grabs the users attention better than using a color ramp. With different sized objects representing data on a map it draws the users attention immediately to the fact that one is bigger than the other. Rather than seeing a specific color and wondering what that color represents the user can identify that one area has more of something or is larger in a number of something than another area without referencing the legend. This could be extremely useful in quick reference products where the title explains the data.