Visualizing Multiple Data Series’ in a Chart
A little while back I featured the stacked column chart below in a post that discussed the ineffectiveness of its design. More often than not, a simple multi-series line graph can do a better job at visualizing data compared to a stacked column chart. The other option is to go with is a panel chart, also known as small multiples. In the R program, this type of visualization is more formally called a Trellis Display.
Besides the overpowering and inconsistent labels, I think the Baltimore Sun did a good job with its recent display of the percent change in the number of passengers from 2008 to 2009. It may have been better to stick with the airport codes, like BWI, instead of writing out the airport names, but let’s not nit pick. I bring this topic up again because I think small multiples or panel charts can be much more effective at visualizing data and, in my opinion, are under utilized in the business world.
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There has been some great work done by a few experts in the Excel and R fields on creating panel charts. Here are a few resources that have examples and information on how to create panel charts in Excel and Trellis Displays in R.
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October 28th, 2009 at 8:43 am
Kelly O’Day coined the term “panel chart” since I thought that the term “trellis display” was trademarked. I now believe that I was mistaken. Bill Cleveland introduced the term “trellis display” since the framework resembles a garden trellis. R uses the term “lattice” to avoid possible trademark violations.
No list of resources on creating trellis (lattice) displays in R would be complete without mention of the books R Graphics by Paul Murrell and Lattice: Multivariate Data Visualization with R by Deepayan Sarkar.
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