If you are someone who regularly presents data to colleagues and superiors as part of your work—whether in simple PowerPoint decks, or in complex dashboards—you would know that converting tables of numbers into a graph can help you get your point across much easier.
What is your go-to way of presenting data visually? When creating graphs for a quick visualisation, do you often find yourself leaning towards pie charts?
While pie charts are the easiest charts to make, and usually the most familiar, here are 6 reasons why you should probably avoid resorting to pie charts to visualise any and all of your data.
1. Pie charts make data hard to estimate
The human eye is not as good at estimating angles as opposed to lengths, and so it can be quite a difficult task to read data represented by slices relative to the whole. This is an even bigger issue in the case of 3D pie charts that skew perspectives.
2. It can be difficult to differentiate between similarly sized slices
Pie charts that have many slices of somewhat similar sizes often lead you to draw wrong or misleading inferences, unless it is labelled with numerical or percentage values—which then makes the chart cluttered.
3. It is an inefficient use of space
Whether in print, in PowerPoint decks, or especially in internal dashboards where there is a lot of information that needs to be quickly conveyed, pie charts take up way too much space. Their shape and the way they depict information does not lend itself well to how we usually structure screens, leaving a lot of white space unused.
4. Pie charts are impossible to label properly when there are a large number of slides
Smaller slices often do not have enough space for names and values. The labelling thus becomes a confusing mess of lines, and the slices rarely allow enough space to include additional information you want to include, like numerical value in different units, percentages, etc. Instead, you would have to use space-intensive graphics like a legend. Even in digital environments that allow users to hover over each slide, very thin slices are tricky to accurately hover over.
5. You will probably run out of colours
Each slice of a pie chart requires a separate colour in order for it to be readable. Often, strict enterprise design and colour guidelines do not allow for the use of a wide range of easily distinguishable colours, and rightly so, because of how messy and unpleasant that can look. Given these constraints, creating large charts with several sections can become a challenge—often sacrificing readability. Furthermore, it also presents accessibility issues for users who are colourblind.
6. Pie charts cannot easily present comparison
Comparing similar data from two separate time periods, or geographical areas are quite necessary when making business decisions. This would require using multiple separate pie charts that do not facilitate any easy comparison between matching metrics.
Should You Never Use a Pie Chart?
Never say never. Pie charts may still be useful in certain situations.
Their strength lies in clearly expressing that you are demonstrating parts of a whole. Someone looking at a pie chart immediately knows that all the different slices add up to 100%.
When there are only 2 (or at most, 3) dissimilar slices, pie charts can be a good option. With very few slices, issues like lack of space for labelling, and overwhelming colour palettes, etc. are not as relevant. And a large difference in their sizes sends a clear message. But remember, it is probably better to avoid 3D pie charts that skew the perception of the angles of each slice.
So, What is my Best Alternative?
You are probably better off creating a bar graph, column graph, or stacked chart in situations you were planning to use a pie chart. Bar graphs, especially, are simple, easily comprehendible, and quite versatile.
Due to how we are better at estimating length, these graphs are much easier to read and infer difference in values from. All the bars are also of even width, ensuring smaller values do not get lost in the mix. They use space efficiently, easily fitting into rectangular spaces, and allowing for easy labelling and including numerical or percentage values. Comparing data is also made simple by plotting a double or triple bar graph or using stacked charts, which takes up less space and puts the required values next to each other.
A dumbbell chart, which arranges values along a line, is a good alternative to pie charts when representing variance. These charts take up far less space while also making it easier for the audience to estimate the difference between given values.
Next time you find yourself about to create a pie chart for a presentation or for a dashboard, do yourself and your audience a favour, and use one of these graphs instead.
Need help elevating your data products for better business insights? Get in touch with us at info@unifyehq.com
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