You can see the final result here: http://www.janwillemtulp.com/eyeo.
The visualization depicts the number of homes and vacant homes for all the counties for each state. The size of the outer bubble represents the total number of homes, the size of the inner bubble represents the number of vacant homes. The y-axis shows the population size (on a logarithmic scale) and the x-axis of the bubbels shows the number of vacant homes per population. Each bubble is also connected with a line to another axis: the population / home ratio. On the top right you can see some exact numbers for this data.
This time I built the visualization in Processing, mainly because I expected to work with large datasets from the US Census Bureau and I might had to use some OpenGL for better performance. Eventually I didn’t use OpenGL. Building the visualization in Processing was lots of fun. To get sense of the data I tried as many as 5 completely different approaches. Here are some of the sketches that eventually led to this visualization (view this selection on my Flickr stream).
The data itself was not very complex, but rather big, and the biggest challenge was to find a creative approach to visualize this data, but without using a map (which would be rather obvious since it’s about locations).