UX Wednesday: 3 reasons why we avoid pie charts
Pie charts, while visually appealing, often fall short when it comes to conveying information effectively. Top management consulting firms, known for their rigorous data analysis, typically avoid using pie charts in their reports. Why?
1. Pie charts make it challenging to accurately compare different segments
One of the primary reasons for this avoidance is that the human eye struggles to assess the relative sizes of pie slices, especially when there are multiple categories. See the example below.
Source: https://byjus.com/maths/pie-chart/
Can you identify any significant differences between English and Science? A column chart could represent such small differences much more effectively.
2. Pie charts are confusing when there are too many categories
Additionally, pie charts become increasingly cluttered and confusing when there are too many categories, limiting their usefulness for displaying complex data sets.
Source: https://www.geeksforgeeks.org/pie-charts/
The chart is not very informative because it's too crowded and difficult to compare. While it does provide exact percentages, a table would be more effective in this situation. Additionally, it's a good idea to set the chart's starting point at 12 o'clock for clarity.
3. 3D is always misleading
Browse through newspapers, news, especially about politics, and you’ll see that many organizations use 3D charts often. They look nice and attractive, but they fail miserably at informing.
Their perspective and the angles are chosen conveniently to exaggerate or to minimize.
Source: https://excel2013training.wordpress.com/2015/01/22/different-types-of-a-pie-chart/
And although there may be figures written on the chart, the segments of such chart (area of the pie chart) will never be proportional to the data.
+ one reason why we love them!
That being said, it's important to note that pie charts are not entirely useless; they do have their niche applications. Pie charts can be effective when comparing just two categories, where they can highlight one category's dominance over the other. In such cases, they can provide a quick, visual representation of the data that makes it easy to discern the relative proportions.
Just like here:
The chart is sourced from our e-book and clearly illustrates that, according to a report from Salesforce, sales representatives spend a staggering 72% of their time on tasks that are not directly related to selling.
However, beyond the simple comparison as above, limitations of pie charts become increasingly apparent. For more complex data sets with multiple categories or when precise comparisons are needed, alternative chart types such as bar graphs, stacked bar charts, or even data tables are generally preferred by professionals, including top management consulting firms, for their clarity and informativeness.
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