Cycle: Bike and Car Traffic Citations in Austin
Technically (according to the officer who pulled me over on my bike) bikes and cars have equal road rights and responsibilities in Austin. I wanted to map a year's worth of traffic citations to see what the data revealed.
One Hundred Sketches
I pulled the cycling data into ArcGIS and used a method called "sketching with data." I created one hundred maps to help me realize what relationships are best shown geographically.
Events that cluster in specific areas, such as driving the wrong way on a one-way street (sketch A), are revealed by geographic mapping.
Geographic visualization does not show magnitude or frequency well. Looking at sketch B, you would not know that 18% of jaywalking citations for the year were issued at one intersection, during one hour. A time-frequency chart would show this information better.
Creating one hundred maps also made me realize that there is a such thing as slicing the data too fine. My dataset started with ten thousand datapoints, but when searching for a relationship between hit-and-run bike accidents and time of day, I was left with six datapoints (sketch C). At this level, it is impossible to find a relationship that is statistically significant.
The One Hundred Sketches exercise was productive in that it generated new theories and ideas for future information graphics.