Misc. Information
Part 3: Interaction Design
Please refer to the interaction demo found in the following slides: Interaction.pdf
The visualizations where I felt interaction would add to their effectiveness were the "Going South, 2007" visualization and the "Population distribution" visualization.
Going South, 2007 (slides 2-6)
Interaction will help us make the trends in this visualization even easier to see. The basic idea is to simulate a zooming-like effect by highlighting data that the user cares about, while fading out the data that the user does not care about. For example, if the user clicks on "from Northeast" (slide 3), then only the points corresponding to "from Northeast" will be opaque and the rest will become transparent (slide 4). Now the trend for "from Northeast" migration is very clear. Taking this one step further, if the user then clicks on "to South" (slide 4), then only the "from Northeast to South" data point will be opaque and everything else will fade out (slide 5). Similarly, if the user had first clicked on the "to South" label, then only the points corresponding to "to South" would be opaque (slide 6). This zooming effect (or, more literally, highlighting effect) makes the data easy to read and interpret. I chose to alter opacity rather than hue or brightness or any other features of the graph for simplicity and to avoid distracting the user with changes that are too drastic.
Population distribution
The population distribution visualization depicts data that changes over time, so interaction will help us actually "see" these changes in motion. I have sketched an animated transition of the population distribution map over time. The user can click play underneath the visualization (slide 8)
and the animation will start. The colors of the states change continuously and uniformly over time (provided their colors in the next time period are different). [NB: This is not depicted in the slides.] Blue "up" arrows over states indicate rising population share while red "down" arrows over states indicate falling population share (slide 9). I chose these colors to naturally coincide with our notion of "positive" and "negative". At first, I drew black arrows above the states, but it was hard to distinguish between up arrows and down arrows, so I chose the red-blue color scheme. The user could ideally change the speed and direction of playback. As always, the main goal of visualization is to clearly present the data, and this interactive animation presents the changes over time in a fun and intuitive way.