A few weeks ago, we wrote the first part of this “crusade” against pie charts that we started at TEFIPRO. In it, we primarily tried to show all the disadvantages of this type of chart.
Now we are going to show how we can visualize the same information with other types of charts in a way that humans can better interpret.
If the human eye is not good at comparing 2D areas or angles, what is it good at?
The human eye is good at comparing differences in 2D locations and differences in line lengths.
And it is precisely there where we will be able to better interpret a chart. Let’s start: ¿what is the relationship between B and C?
To solve it first, we need to go to the legend, identify the corresponding color, and then judge their angles.
Next, we will show the same information with another type of visualization that is better suited to human abilities.
C is almost half of B, and in the pie chart, they looked very close. It could be due to the human eye, the screen ratio of the device it’s viewed on, or some other factor, but the reality is that the pie chart does not convey the relationship.
What could be worse than a pie chart?
Many pie charts 🙂 Therefore, below we can see several pie charts showing how a market evolves. (Click to enlarge the chart)
It is very difficult to draw any conclusions about how the market has evolved from a glance at the pie charts. At the very least, it’s not easy; special attention must be given to the portion, and one must “mentally” transfer that area, rotate it, and place it over the portion from another period…
Here are the same data as bar charts: (try to draw some conclusions with a brief glance).
With the bar chart, at first glance, we can see that product D is standing out and increasing its sales, while B and C are declining.
However, if the goal of the visualization is to show how the market has evolved over time, a line chart will be more useful:
In it, in addition to seeing the trend in the market for each product, we can see snapshots (2005, 2006, …)
In summary, remember that:
The weak points of human vision are judging angles and 2D areas, but we are good at judging differences in length and 2D position.
That is where we can focus our efforts to be more efficient in displaying visual information.
We hope that these two articles on pie charts and their alternatives have been interesting and, above all, useful.