A Quick Guide to Spotting Graphics That Lie

1. BROKEN SCALES SHOW DRAMA WHERE IT DOESN’T EXIST.

This might be the most common way graphics lie. Something that changes by 1% over 10 years and something changes by 100% over 1 year could look like exactly the same trend and range on the chart. Be careful with the truncated Y-axis, which is quite misleading.  A good example is:

At a glance, the blue bar looks much bigger than the red bar, as the Y-axis starts from 0.400 and each point is 0.05 more. However, when displaying the data with a zero-baseline Y-axis tells a more accurate picture, where the difference is not that much.

2. SHOWING DATA ON TWO DIFFERENT SCALES CAN MAKE FOR AN UNFAIR COMPARISON.

Is 100kg more or less than 10 feet? You can’t give the answer, right? Because the units are different. We can’t compare two different elements, even though they are in the related field. A good example is:

Looking at the chart on the left could make you think U.S. gross domestic product (GDP) surpassed the unemployment rate around March 2015. But that comparison is meaningless if you put them in the same graph.

3. IGNORING POPULATION SIZE MAKES RATES IMPOSSIBLE TO COMPARE.

When talking about number, translating to percentage is usually more convincible and scientific, as you should keep in mind the whole population or the total. A good example is:

Chicago suffered more murders in 2014 than Detroit, but that doesn’t mean they’re more dangerous. If you consider the population of each city, the comparison changes greatly, as Detroit came to the most dangerous position.

4. DECORATION CAN BE DECEIVING.

Be careful when you choose some very shinning charts. Too many decorations may display the real value in a misleading vision. A good example is:

A 3-D model looks more modern. The number shows that Christians should be the biggest group. But due to the 3-D effect, the Muslims seems occupies a larger amount of green on the left chart.

Reference:

http://blog.heapanalytics.com/how-to-lie-with-data-visualization/

http://news.nationalgeographic.com/2015/06/150619-data-points-five-ways-to-lie-with-charts/