Spatial perception: on the chart and in real life

A twitter follower @mdjoner felt that something is amiss with the squares in this chart comparing real estate prices in major cities around the world. I'm not sure where the chart originally came from but there is a CNBC icon.

There is one thing I really like about the chart, which is the metric that has been selected. The original data is likely to be price per square metre for luxury property in various places. The designer turned this around and computed the size of what you can buy assuming you spend $1 million. I think we have a better ability to judge areas than dollars.

The notion of floor area meshes well with the area on a chart, so there is an intuitive appeal as well.

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So in the Trifecta checkup, they did well posing an interesting question, and picking some data. But like Mike, I'm not excited about the graphical construct.

There are a few problems with this chart:

• It requires using colors when the colors do nothing other than delineating one city from the next.
• There's overcrowding at the bottom of the chart because the designer maintained a fixed spacing throughout the chart.
• The city label is always positioned above the middle of the diamond. I find it very confusing in the bottom half of the chart when the diamonds started overlapping.
• The shadows plus the overlapping make it almost impossible to make out the actual areas of the pieces.

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Here is an alternative display of the data:

Notice that I designed this for an American audience. I'd change certain decisions if using this for the non-American reader. I choose New York as the focal point, and split the cities into two parts. On the left are the cities less expensive than New York and on the right are those cities more expensive than New York.

Also, along the bottom, I provide some clues to help people bridge the gap between the areas shown on the graphic, and real-life areas. For example, the orange square represents 400 square feet but without the annotation telling you it's about the size of a typical Manhattan studio, you may not know how to map the size of the orange square to your perception of real spaces. I also included images (although if I'm publishing this, I'd want better ones).

Finally, note that the data set did not show up on my version of the chart.