Pie charts are a common way to visualize data, but they often receive criticism for being difficult to interpret effectively. Take this visualization for example:
As you can see, even with labels, discerning precise values from pie chart segments can be challenging. The primary issue with pie charts lies in how our brains perceive visual information. We struggle to accurately assign quantitative values based on two-dimensional areas. In simpler terms, pie charts aren’t inherently user-friendly for detailed data analysis. Comparing segment sizes, especially when they are similar, becomes an exercise in guesswork. While we can identify the largest slice, judging the magnitude of difference between segments is nearly impossible without added data labels, as seen in the example from TechCrunch. However, even with labels, the visual impact of a pie chart often doesn’t justify the space it occupies.
So, what’s a more effective alternative? A horizontal bar chart is frequently recommended as a superior substitute for pie charts. Organizing bars from largest to smallest, or vice versa, allows for immediate and accurate comparison, unless category order holds intrinsic meaning.
Bar charts leverage our visual system’s strength in comparing lengths along a common baseline. This makes it significantly easier to not only pinpoint the largest category but also to judge by how much it exceeds others. Using the same TechCrunch data, a bar chart provides a much clearer and more digestible visualization, allowing for quick insights that are often obscured in pie charts, especially when trying to highlight market leaders and smaller segments within a dataset.
