The Evils of Graph Clutter

In school, we are all taught the “rules” of how to draw a graph.  Every graph should have well defined axes, labelled at equal intervals.  Every axis should have a title.  And, we are always told to add loads of clutter to graphs – gridlines, error bars, trend lines – the more, the better.

When people come into business, these rules are still ingrained in their psyches.  And they shouldn’t be.  Any modern data visualization tool in the right hands can make powerful and intuitive charts without any of this clutter.

By way of example, imagine a bullet chart showing sales revenue against budget.  Here is how it might look following the “school rules” of graph drawing.  Everything is labelled and titled.  We have gridlines, trend lines and an axis which starts at 0.   

There is a lot wrong with this graph. 

• Do the gridlines add anything, or are they just distracting?
• Do we need axis titles? We’ve been told it’s a graph about revenue in the chart title and anyone with a bit of common sense can tell that Jan, Feb and Mar are months.

However, the main problem with this graph is that its message is obscured.  The graph claims to be showing revenue against budget.  For each month, I want to know whether we are above budget or not and by how much.  It is hard to get that information from this graph.

Here is the graph I would draw.  I’ve used a fantastic tool called Tableau, which I would definitely recommend.

Notice that all of the clutter has gone.  No gridlines, no axis names.  The trend line was only trending the actual revenue – that’s nothing to do with the message of this graph, so the trend line went as well. 

I've used color to emphasize the message of the graph.  I try not to use a green=good, red=bad color scheme, because red and green look horrible next to one another and red/green color blindness is fairly common.  Within your corporate color scheme, you can choose a "good" and a "bad" color. 

I removed the Y axis all-together.  Tableau has a great tooltipping feature.  Why approximate the value of each bar from an axis when a tooltip can give us the exact numbers? 

This also means that I don't need to start my Y axis at 0 and more real estate can be spent emphasizing the relative difference between actual and budget.  You need to be careful when doing this as it can distort the numbers.  I've added labels on the bars to guard against distortion.

I implore people to forget all of the rules they learned about drawing graphs in school and replace them with a single rule.

“A graph should show what I intend it to show in a intuitive way, without any unnecessary graph clutter”.