The Bloomberg team has come up with a few goodies lately. I was captivated by the following graphic about the ebb and flow of U.S. presidential candidates across recent campaigns. Link to the full presentation here.
The highlight is at the bottom of the page. This is an excerpt of the chart:
From top to bottom are the sequential presidential races. The far right vertical axis is the finish line. Going right to left is the time before the finish line. In 2008, for example, there are candidates who entered the race much earlier than typical.
This chart presents an aggregate view of the data. We get a sense of when most of the candidates enter the race, when most of them are knocked out, and also a glimpse of outliers. The general pattern across multiple elections is also clear. The design is a stacked area chart with the baseline in the middle, rather than the bottom, of the chart.
Sure, the chart can disappoint those readers who want details and precise numbers. It's not immediately apparent how many candidates were in the race at the height of 2008, nor who the candidates were.
The designer added a nice touch. By clicking on any of the stacks, it transforms into a bar chart, showing the extent of each candidate's participation in the race.
I wish this was a way to collapse the bar chart back to the stack. You can reload the page to start afresh.
This elegant design touch makes the user experience playful. It's also an elegant way to present what is essentially a panel of plots. Imagine the more traditional presentation of placing the stack and the bar chart side by side.
This design does not escape the trade-off between entertainment value and data integrity. Looking at the 2004 campaign, one should expect to see the blue stack halve in size around day 100 when Kerry became the last man standing. That moment is not marked in the stack. The stack can be interpreted as a smoothed version of the count of active candidates.
I suppose some may complain the stack misrepresents the data somewhat. I find it an attractive way of presenting the big-picture message to an audience that mostly spend less than a minute looking at the graphic.