Think Before You Stack
June 24th, 2009I hate to beat this to death, but I continue to see charts like the one below featured in excellent periodicals like BusinessWeek. As I said in a previous post, I really dislike stacked bar charts, ESPECIALLY when time is on the x-axis. To help illustrate my point, here are a few questions:
1) How much did the Subprime (yellow) dollars change from month to month or between any points?
2) Is there even a value for Subprime after about March 2013?
3) How many times do you have to reference the legend to figure out which color is what label?
The only value that is easy to visualize and analyze is the Agency data that is in black and the first data series. Beyond Agency, this data visualization is useless. I tried to get the data to make a better chart, but couldn’t locate it. Instead I ask that you visualize 7 lines in a line chart, one for each value and the 7th one for the total. Using that chart, you could easily see the trend in each value and also the overall change.
Yes, this chart is colorful and caught my eye, but it’s also worthless.
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Below is another example using similar data where the data visualization is completely ineffective.
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