GIS 6005 - Communicating GIS - Module 6

  

Once my layout was completed, I tweaked my symbol classes to make the job loss red circles, and job gain blue circles the same size, relative to the equivalent number on the opposite side.  Then, I added another copy of the job gain category, and changed the symbology to hollow circles with black outlines. (This was done in order to include all circles, and communicate that the number associated is symbolized by the size of the circle.)

After ungrouping the legend, I stacked the circles in order of size and labeled them with appropriate labels. Then, I created a secondary legend that explained the colors displayed on the map, and placed it above the first legend. Between the two of these legends, the colors, as well as the sizes of the circles are communicated, and the same circle size can be applied to all circles.

Color values presented are in the HSV color model. (Transparency is set to 0 for all values)

A1 – 0, 0, 96.08

A2- 171, 37.56, 80.39

A3 – 175, 99.02, 40

B1 – 42, 43.95, 87.45

B2 – 92, 11.87, 66.08

B3 – 156, 62.89, 38.04

C1 – 33, 92.86, 54.9

C2 – 45, 70.53, 41.25

C3 – 92, 43.17, 35.88

I began by generating a dividing color ramp in Color Brewer, and selected 9 classes. I chose the middle value as A1, then every other value in each direction as the next value diverging from A1. (Teal for numbers, Brown for letters)

Next, I calculated the rest of the table by adding the RGB values of opposing extant cells, and dividing the results by two, as we had done in the chloropleth module.

If a color palette is chosen well, and the values are easy to distinguish for the typical person, two distinct values can be simultaneously communicated in a single map. While three value classes may not be very thorough in communicating specifics of the degree for each value, the correlation can be communicated very well by showing areas of concentration for both variables.