September 25, 2009, 3:32 pm
Data in the Round
By Henry Woodbury
An interesting, but flawed chart at O&G Next Generation shows how much oil the United States imports from other countries:
There are several big problems with this chart. First, U.S. oil imports per day by country is linear data. When one-dimensional values are presented as two-dimensional areas, proportional differences between values are rarely perceived correctly. This problem is compounded by the placement of the data blobs on the global map. It is good to attach each blob to a country, but not good to scatter them both vertically and horizontally. With a little design attention the values could be presented as bars and aligned along a single x-axis in the tropics.
Another problem is that several important data points aren’t shown. Most importantly we need a figure for the United State’s domestic production. This is vital for context. Upon investigation, we find that the bar chart on the bottom left is either not accurate or not tracking the same petroleum product as the map. If you subtract Total Imports from U.S. Consumption for 2008 you get a ballpark figure of around 6,000 thousand barrels per day. This is far off the mark. The real number for 2008 is 4,921 thousand barrels per day, a little bit less than total U.S. crude produced since a small amount of U.S. crude is exported. In June 2009, domestically produced minus exported crude is 5,126 thousand barrels per day.
Another missing figure is the total of oil imports from all countries after the top 10. Once we can look up the June 2009 total for all countries — 9,172 thousand barrels per day — we can easily calculate the sum of all countries after the top 10. The long tail total turns out to be 1,613 thousand barrels per day which is greater than all but Canada. The 9,172 total and various subtotals also allow us to validate the 82% percentage on the far right and update the 2007 ratio of 60% to the actual June 2009 ratio of 64%.
If we add circles to show the oil consumed by the United States from its own production and the “Rest of World” total identified above, the chart looks something like this:
It is even more difficult to read. But that’s not a problem with the data. The data needs to be shown. The problem is with the presentation. The chart still shows linear values with areas, it still doesn’t show totals, it still uses an out-of-date figure from 2007 on the far right, it still has questionable, out-of-date data on the bottom left, and it still has a jumble of factoids on the bottom right that don’t relate the data above. Alas, I am out of time.
