Since 1999 the United States has experienced a dramatic increase in the number of new syphilis cases. The University of Iowa Computational Epidemiology Group has put together 17 years of state-level syphilis data and visualized this data. The visualization is a animated heatmap that shows the case count numbers for all states on a weekly basis.
While I think the heatmap does a fairly good job at giving an overview at a given timestamp it is hard to really grasp varieties on different dates. The playback feature helps in this regard but for deeper analysis some sort of direct comparison would be crucial.
Gapminder.com with it’s “traces” mode comes to mind while thinking of possible ways on how to combine timeline based animation and direct comparison over multiple timestamps. Another way would be to introduce a split-screen solution, which I feel would be a inferior solution in terms of usability. Are there any concepts out there that let’s a user compare different states of a heatmap? I would love to hear your thoughts on this.