Cutting or not cutting the Y-axis is probably one of the most disputed topics in data visualization, as here, here and here. Basically, the issue is whether or not the Y-axis should always start at zero. Let’s try to find out why it is a struggle to gain consensus on this topic.

When it is bad

Let’s start with a barplot showing the issue:

When it is good

“In general, in a time-series, use a baseline that shows the data not the zero point” - Edward Tufte

So how to choose

By its design, a bar graph emphasizes the absolute magnitude of values associated with each category, whereas a line graph emphasizes the change in the dependent variable (usually the y value) as the independent variable (usually the x value) changes.

• Barplot: With this kind of chart there is consensus: your Y-axis should starts at 0
• Line plot: Here however there is no consensus, even if in general you don’t have to start at 0.

Read more:

• Have a look to this #SWD challenge by storytelling with data: you will see that most of the entry ordered their barplot.
• Read more about barplot and lollipop plot
• Have a look to the collection of dataviz pitfalls:

Comments

Any thoughts on this? Want to share another common dataviz pitfall? Disagree? Please drop me a word on twitter or in the comment section below: