Part of the “How Not to Visualise Data” series #HNTVD 🥧
Ah, the humble pie chart. Once the darling of business presentations, now the mischief-maker in the data visualisation world. Much like bringing a crumpet to a sword fight, overusing pie charts can lead to misinterpretation and confusion. Let’s slice through the reasons why pie charts can be misleading and serve up a tasty alternative.
A Common Mistake: Overusing Pie Charts
Overusing pie charts is like inviting your eccentric uncle to every family gathering – charming at first, but quickly past its due date. Pie charts are often misinterpreted, especially when there are many slices or the differences in values are tiny. The more slices you add, the harder it becomes to compare them accurately.
Why Pie Charts Fail
Pie charts fail when they are overloaded with information. Human eyes struggle to compare angles and areas, making it difficult to discern slight differences in data values. When faced with a pie chart filled with numerous slices, our brains turn into a muddle, leading to misinterpretation and poor decision-making.
Can we define an Overloaded Pie Chart?
So we know that presenting sales data for 20 different products in a pie chart results in a colourful wheel of fortune. Not only does this make it difficult to compare values, but it also gives the impression that all slices are equally important. But how many slices? There is no agreement in the world of best practice.
Some say: “None!!”
Others: maximum of 7.
Some others: up to 3 or 4.
In my humble opinion, they are actually pretty good for 2 – but only because people intuitively understand the pie chart and see which one is bigger instantly.
📊 Using Bar Charts Improves Accuracy
Instead of pie charts, opt for bar charts to provide better accuracy in comparing values. Bar charts, with their straightforward, linear nature, allow for easy comparison of data points. Converting our overloaded pie chart into a bar chart instantly clarifies the differences in product sales, making the data easier to digest.
In the world of data visualisation, pie charts are like the marmite of graphs – divisive and best used sparingly. By understanding their limitations and knowing when to use alternatives like bar charts, you can ensure your data tells a clear, accurate story.
So, next time you’re tempted to whip out a pie chart, remember: less is more, and clarity is king.
