In this particular case, where the point is to show the difference between two groups (not three or four) it is acceptable to use the stacked bar graph approach. This technique emphasizes the difference between the two groups. When people use the same technique with three or four groups, it becomes very difficult to pick out the visual differences. But the folks at the Economist stuck to two groups and it does show the difference in earnings between singles and married-with-two-kids people.
What Needs Work
The picture is not helping anything. Please, people, think twice before inserting stock photography in your infographics. There should never be an element of an infographic that fails to communicate information clearly. The whole money in the clouds motif is also…questionable in terms of the art direction.
Aside from my qualms about the aesthetic choices, I have a more important contention. It would seem that the point of this graphic is to suggest that married people operate under more favorable tax laws than unmarried people. If that is the case, I think it would be nice to see some information about the taxes coming into play. I say this in part because the commenters to the article revealed that they mistakenly believed this data is pre-tax. But it isn’t. Furthermore, this graphic implies that marrieds have more money on hand than singles in the same income brackets, but that isn’t necessarily true either. Those kids do cost something – they need clothes, food, bigger houses, bigger cars, and an endless list of other things. So even though Mr. and Ms. Single do not take home as much, I bet they have fewer carrying costs. Granted, the graphic is about taxation policy, not about discretionary spending opportunities, but it fails to emphasize taxation and leaves itself open for other interpretations. These interpretations are available for your reading pleasure in the comments section following the original post. I do encourage you to read the comments because it makes clear that people do not read, not even the single paragraph of explanatory text.
Economist Online Staff. (11 May 2010) Single supplement: The average single worker takes home less than his married counterpart. The Economist online.