To read management information correctly, you often need good visual judgment. At least, it seems that way. Are you good enough to interpret the visualizations that you are expected to? Take the test and see for yourself!

The New York Times recently used a chart based on area size to illustrate how the market value for the largest U.S. financial institutions has changed over the past year. The hollow square represents the 2007 value while the filled square stands for the current one. Now, try to guess how much the market value for Citigroup, Bank of America, Berkshire Hathaway and AIG has changed in percent over the past year.

If you enter your estimates in the following fields and click ‘Evaluate’, you will learn how good your visual judgment really is.

I recently took this test along with a few friends and colleagues. On average, we were 24% off target. That’s too much if you ask me. This test clearly backs the existing arguments against using areas in charts, which were first introduced – alongside time series, bar and pie charts – by William Playfair in the 18th century.

One stipulation for a good chart is that observers can read it accurately. One requirement for good managers, on the other hand, is that they demand the information that they need. As our little test shows, charts based on areas and good management do not go hand in hand. Therefore, when we don’t need anything else to understand management information, we prove that our (visual) judgement is good.

The original chart, which was posted in the Sunday edition of the New York Times (2008-09-21), does contain the actual numbers. I think that this chart serves its purpose…namely, as decoration. Since the New York Times usually serves as a role model for information design, we can deal with a bit of ornamentation on a Sunday. On workdays, however, managers both with and without good visual judgment always should go strictly by the book.