Thursday, August 22, 2019

How Far is a Mile?

One thing I nearly always omit from the interactive maps I create is a distance scale. This could be a big mistake. It turns out that most people are pretty bad at estimating distances on maps. Including me.

You can find out how good you are at estimating distances on a map using this Distance Perception Study interactive map. The map simply asks you to draw a circle with a radius of one mile on a location that you are familiar with. When you have submitted your circle you are then told how accurate your circle was.

When I attempted to draw a one mile circle centered on my house I was way out. The circle I drew was actually 0.72 of a mile. So I therefore underestimated the distance of a mile by more than 25%. This is embarrassing - but on the plus side - my favorite pub is actually a lot nearer than I always thought it was.

If you attempt the study yourself you might actually be asked to draw a circle that represents a 5 minute walk or a circle that represents a 5 minute drive rather than draw a circle that represents a mile. The study asks at random one of these three distances.

The Distance Perception Study map is actually part of Dave Michelson's research project for his Masters of Liberal Arts and Sciences. You can read about some of his initial findings from the study at Can Users Estimate Distance on Web Maps? According to the results so far it turns out that I am not alone in underestimating the length of a mile on an interactive map. On average participants in the study have underestimated the distance of one mile by 1,486 feet.

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