Ryan McCarthy linked to a post by Ruchir Sharma running on Ezra Klein's blog analyzing global billionaires.

It has an accompanying chart, which fails our self-sufficiency test. That test involves erasing raw data from a chart, and figuring out how much information the graphical elements themselves convey.

The primary metric used by Sharma is the billionares' total net worth as a percentage of the country's GDP. This metric is embedded in double concentric circles. Unfortunately, without mental gymnastics, readers can't tell what the proportion is. This means we must look at the raw data which is supplied as a column on the right of the graphic. If readers are taking the information from the column of raw data, then why draw a chart?

The actual data is revealed on the left . Don't tell anyone you read it here but pie charts would work well with this dataset. You might complain that there is a conceptual problem - that if we sum up the net worth of everyone in a country, it would not equal GDP. I think the sum doesn't work - economists can chime in about this. Sharma seems to imply that the total would sum to 1. Anyone's net worth is accumulated over a number of years in which the GDP is fluctuating while the total GDP is given for a specific end of quarter of some year so does it make sense to divide one by the other?

Also, the fact that some people may have negative net worth creates problems with the pie-chart format and it's not much better in a concentric-circle format either.

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A maddening decision puts the United States, which is the biggest circle, at the bottom of the chart. Notice that the countries are sorted from larger billionaires' share to smaller. The U.S. belongs to the top 5 nations with the worst inequality by this metric and yet a cheeky little bookmark sends us to the bottom of the list together with the more-equal nations.

Not only is the location of U.S. privileged, the location of the text, the number of decimal places given in the net worth amount, and the presence of the GDP value all set the U.S. apart from the other countries plotted.

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The most interesting piece of information is waiting to be reconstructed. In Malaysia, nine citizens own as much as 18.3% of the country's GDP. In Mexico, 11 people own 10.9% of the country's GDP.

To make the number even more telling, we have to incorporate the population size. For Malaysia it is 28 million. This means that the top 0.000032% of the population owns 18.3%. In the case of perfect equality, this proportion would own 0.000032%. We can say the inequality index is 570,000. In Mexico, the index is 1.1 million. So in fact, the concentration of wealth at the time is worse in Mexico than in Malaysia. For reference, the U.S. comes in at 78,000.

Of course, the use of billionaires as a filtering device to determine who to count or not is completely arbitrary. In measuring income inequality, one should look at what proportion of the population control 50% of the wealth, for example.

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There is no explanation for the choice of countries. The U.S. is the only developed nation in the entire chart.

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