September 2, 2009, 2:20 pm
What’s Wrong with this Chart?
By Henry Woodbury
The chart, of Federal Spending FY 2009 YTD, is from USAspending.gov, a web site mandated by law to provide the public free, searchable information about U.S. Federal expenditures.
Seth Grimes at Intelligent Enterprise figures out the problem and its cause:
USAspending.gov produces its charts dynamically using the Google Chart API…[but] passes values to Google that are out of range. Google truncates them, just as [its] documentation explains.
Here is Grimes’ corrected chart:
Unfortunately, data misrepresentation isn’t the only problem he finds.
Comments
What else is wrong with the chart?
Drawing it with fake 3D features might make some think it’s more attractive, but this is at the expense of readability.
Sorting of the data points would improve readability.
Replacing the legend in the original (which isn’t even shown in these examples) by labels that include category as well as percentage, would improve readability.
Despite teh pie chart’s supposed superiority at showing part-to-whole relationships, a bar chart would display the data in a clearer form.
Posted by Jon Peltier on September 4, 2009 at 7:10 am