November 11, 2015

Let the Truth be Told

I was recently presented a line chart that looked very similar to the one below:


 
At first glance, I thought it was designed fairly well. After all, the designer wanted to show the scoring trends for these 5 countries over time. The line chart was seemingly a wise choice as they’re great for showing the shape, velocity and direction of data over time.

However, until I looked at the labels, I was thinking that highest score for 2012 Q3 (United States) was over 3x or 300% higher than the lowest score (England).When in actuality, the US score isn’t even 7% lower.

How could this be?

Hint: Look at y-axis.

Does it Start with Zero?

No, it starts with 3.9.

It’s doubtful that the designer did this to deceive his or her audience (although there are plenty of examples where deception is the ultimate goal). Most likely they did so to avoid what you see below:
 

So what can I do to avoid a situation like the one above where a y-axis with an origin of Zero lead to a visual that’s impossible to analyze?

The answer may seem a bit simple: Annotate! Let the truth be told. Don’t assume that your audience will figure out something like this so find a way to tell them.

Here’s one possible solution:




You want your annotation to be noticeable but avoid obstructing the view of the data itself.

Annotation is a feature that most tools will allow you to apply directly on your charts. If not, be creative and find an alternative solution to ensure your audience understands the story you are telling.

Cheers,

Kevin A. Taylor


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