Horizon Graphs Revisited

For the June/July issue of the Visual Business Intelligence Newsletter, I wrote an article titled “Time on the Horizon,” which featured a new time-series visualization called the horizon graph. Developed by Panopticon, horizon graphs can meaningfully display 50 or so full sets of time-series values on a single screen or page in a way that supports comparisons among them. The following example displays a year’s worth of stock prices for 50 separate stocks (one per row).

Click the image to enlarge it.

Though it takes some getting used to at first, once you’ve learned how to read it, it works quite well.

As it turns out, three information visualization researchers at the University of California, Berkeley became interested in horizon graphs and decided to put them to the test. To my delight, and no doubt that of the folks at Panopticon as well, the horizon graph performed well and some useful guidelines for its use were discovered.

I found this research inspiring, not only because of the results, but because it is such a fine example of the kind of constructive collaboration between software vendors and academic researchers that we desperately need. No, these researchers weren’t paid by Panopticon to confirm their work. In fact, neither I nor Panopticon knew about this until after the research was complete. This wasn’t the kind of collaboration that can sometimes get messy when money’s exchanged, but the kind that arises naturally from a group of researchers’ desire to apply their talents to something tangible-something that has a good chance of actually being used.

This research, done by Jeffrey Heer, Nicholas Kong, and Maneesh Agrawala, was well designed, well conducted, and written up beautifully in the paper “Sizing the Horizon: The Effects of Chart Size and Layering on the Graphical Perception of Time Series Visualizations”. It will be presented at CHI 2009 in April (CHI stands for Computer-Human Interaction) and has been nominated for the CHI Best Paper award.

Take care,

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